Tantalum-tungsten alloys (Ta-2.5W and Ta-10W) Ta-W
Tantalum alloyed with 9.0 to 11.0 wt% tungsten (Ta-10W, UNS R05255) or 2.0 to 3.5 wt% tungsten (Ta-2.5W, UNS R05252), balance tantalum · body-centred cubic
Also known as UNS R05255, UNS R05252, ASTM B708, Tantaloy 60, Tantaloy 63, ATI Ta10W
Tantalum-tungsten alloys are refractory metals.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Melting
3035 °C
Strength when cold
481 MPa minimum
Strength when hot
36,200 to 37,100 psi at 2600 °F
Coating life
50 hours at 2200 °F
Density
16.9 g/cm3
Recipe, share of the weight
- Ta balanceTantalum
- W 9 to 11%Tungsten
Best for
Hot structural and nozzle parts that need ductility and corrosion resistance at elevated temperature, with a protective coating where the part sees hot air
Weakest at
Weight (16.9 g/cm3 for Ta-10W) and oxidation in hot air: the sources give coating lives, not uncoated lives
Risk at a glance
- People Low. Bulk metal: low hazard; powder can ignite
- If it fails Moderate. Coating breakdown in hot air
- Corrosion Moderate. A coating protects Ta-10W in hot air for a limited time: about 45 hours at 2000 °F in a NASA test.
Quick facts: Ta-W
| Property | Value | Basis |
|---|---|---|
| Density | 16.7 to 16.9 g/cm³ | 2 sourced values across conditions |
| Yield strength | 193 to 614 MPa | 3 sourced values across conditions |
| Tensile strength | 240 to 655 MPa | 4 sourced values across conditions |
| Young's modulus | 186 GPa | 1 sourced value |
| Hardness (Brinell) | 185 to 210 BHN | 1 sourced value |
| Thermal conductivity | 55 W/(m·K) | 1 sourced value |
| Melting point | 3,014 to 3,035 °C | 2 sourced values across conditions |
| Specific heat | 141 J/(kg·K) | 1 sourced value |
What is the density of Tantalum-tungsten alloys (Ta-W)?
Tantalum-tungsten alloys (Ta-W) has a density of 16.7 to 16.9 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of Tantalum-tungsten alloys (Ta-W)?
Tantalum-tungsten alloys (Ta-W) has a thermal conductivity of 55 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the melting point of Tantalum-tungsten alloys (Ta-W)?
Tantalum-tungsten alloys (Ta-W) has a melting point of 3,014 to 3,035 °C. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the yield strength of Tantalum-tungsten alloys (Ta-W)?
Tantalum-tungsten alloys (Ta-W) has a yield strength of 193 to 614 MPa. The range covers 3 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the tensile strength of Tantalum-tungsten alloys (Ta-W)?
Tantalum-tungsten alloys (Ta-W) has a tensile strength of 240 to 655 MPa. The range covers 4 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What are the other names and codes for Tantalum-tungsten alloys (Ta-W)?
Tantalum-tungsten alloys (Ta-W) is also written as UNS R05255, UNS R05252, ASTM B708, Tantaloy 60, Tantaloy 63, ATI Ta10W. Each code is printed in the source listed beside it in the designations table.
What is Tantalum-tungsten alloys (Ta-W) used for?
Uses recorded in the sources include Rocket nozzles, inserts and directional devices (aerospace, high temperature); Heat-shield panels (ground oxidation tests, NASA Langley 1966); Aerospace fasteners and furnace components (distributor claim).
Why it exists
Tantalum-tungsten alloys keep their strength at high temperature and resist corrosion, which is why they are used for hot parts. Ta-10W is the stronger grade with 9.0 to 11.0 % tungsten (UNS R05255), and Ta-2.5W has 2.0 to 3.5 % (UNS R05252). ATI describes the alloy for elevated-temperature aerospace parts such as nozzles, inserts and structural material. Its main limit is oxidation in air: the sources we hold give coated lives in hours, and no life for bare metal.
Where it's used
Aerospace hot parts
ATI describes Ta-10W for elevated-temperature use in aerospace, including nozzles, inserts, directional devices and structural materials.
Heat shields, tested on the ground
A 1966 NASA Langley study tested coated Ta-10W sheet for heat-shield use and built corrugated heat-shield panels from it. It was a ground study, not a flight.
Fasteners and furnace parts
A distributor lists aerospace fasteners, furnace components and electrical connector pins as uses for its Ta-2.5W rod. That is a supplier claim, not a test result.
Recipe
Tantalum alloyed with 9.0 to 11.0 wt% tungsten (Ta-10W, UNS R05255) or 2.0 to 3.5 wt% tungsten (Ta-2.5W, UNS R05252), balance tantalum
Tantalum-tungsten alloys are tantalum metal with tungsten added in solid solution. Ta-10W (UNS R05255) holds 9.0 to 11.0 % tungsten by weight, and Ta-2.5W (UNS R05252) holds 2.0 to 3.5 %, with the rest tantalum. The GS Alloy summary of ASTM B708 lists electron-beam furnace or vacuum-arc melting as the routes for these grades.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Tantalum Ta | balance | The base metal. It is a refractory metal with a high melting point and good corrosion resistance (ATI). |
| Tungsten W | 9 to 11% | Adds strength and high-temperature stability. Tungsten has the highest melting point of the elements, which the alloy inherits in part. |
Weight shares are as printed in the sources.
What it can do
Melting
3035 °C
measured
ATI gives a melting point of 3035 °C for Ta-10W. A distributor gives 3014 °C for Ta-2.5W. The two figures are for different grades, so they should be read side by side, not ranked.
Strength when cold
481 MPa minimum
measured
ASTM B708 sets a minimum tensile strength of 481 MPa for Ta-10W plate, sheet and strip, and a minimum yield strength of 414 MPa. The minimum for Ta-2.5W is 276 MPa tensile and 193 MPa yield.
Strength when hot
36,200 to 37,100 psi at 2600 °F
measured
ATI gives 36,200 to 37,100 psi ultimate tensile strength at 2600 °F for recrystallized Ta-10W sheet, against 80,000 to 95,000 psi at room temperature.
Coating life
50 hours at 2200 °F
measured
In ATI's cyclic tests, a silicon coating on Ta-10W lasted 50 hours at 2200 °F. A 50Sn-50Al coating (weight percent) lasted 290 hours at the same temperature.
Density
16.9 g/cm3
measured
ATI gives a density of 16.9 g/cm3 for Ta-10W. A distributor gives 16.66 g/cm3 for Ta-2.5W.
How it compares
Ta-10W and Ta-2.5W are both heavy: ATI gives 16.9 g/cm3 for Ta-10W, and a distributor gives 16.66 g/cm3 for Ta-2.5W. The melting points printed are 3035 °C for Ta-10W (ATI) and 3014 °C for Ta-2.5W (distributor), two different sources and two different grades. Ta-10W has the higher minimum strength in ASTM B708, at 481 MPa tensile against 276 MPa for Ta-2.5W, and the lower minimum elongation, at 15 % against 20 %. The table compares the two grades on density, melting point and tensile strength.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details.
| Measurement | Ta-W |
|---|---|
| Thermal behavior and safety | |
| Melting point, Ta-10W (ATI Ta10W) | 3035 °C2 |
| Thermal expansion strain, Ta-10W from room temperature to 5250 °F | 0.0222 -12 |
| Thermal conductivity, Ta-10W at 1700 K | 0.135 cal/(cm² sec K/cm)13 |
| Thermal conductivity, Ta-10W at 3200 K | 0.082 cal/(cm² sec K/cm)14 |
| Melting point, Ta97.5/W2.5 (Ta-2.5W) rod | 3014 °C27 |
| Specific heat, Ta97.5/W2.5 (Ta-2.5W) rod | 141 J/(kg·K)28 |
| Thermal conductivity, Ta97.5/W2.5 (Ta-2.5W) rod | 55 W/(m·K)29 |
| Lifetime and stability | |
| Cyclic coating life, silicon coating on Ta-10W at 2200 °F | 50 h15 |
| Cyclic coating life, 50Sn-50Al coating on Ta-10W at 2200 °F | 290 h16 |
| Cyclic oxidation life, coated Ta-10W coupon at 2000 °F | 45 h33 |
| Physical and electrical | |
| Density, Ta-10W (ATI Ta10W) | 16.9 g/cm³1 |
| Ingot hardness, Ta-10W | 185 to 210 BHN3 |
| Density, Ta97.5/W2.5 (Ta-2.5W) rod | 16.66 g/cm³26 |
| Vickers hardness, Ta97.5/W2.5 (Ta-2.5W) rod | 115 to 160 kgf/mm231 |
| Substrate thickness loss, coated Ta-10W coupon at 2000 °F | 9×10^-4 inch34 |
| Temperature behavior | |
| Recrystallization temperature, Ta-10WRange printed in a manufacturer datasheet | 2400 to 2800 °F |
| Other measurements | |
| Tensile strength at room temperature, recrystallized sheet | 80000 to 95000 psi4 |
| Yield strength at room temperature, recrystallized sheet | 70000 to 89000 psi5 |
| Elongation at room temperature, recrystallized sheet | 20 to 40 %6 |
| Tensile strength at 2600 °F, recrystallized sheet | 36200 to 37100 psi7 |
| Tensile strength at 3000 °F, recrystallized sheet | 15000 to 16000 psi8 |
| Tensile strength at 2000 °F, stress-relieved sheet | 60700 psi9 |
| Yield strength at 2000 °F, stress-relieved sheet | 55100 psi10 |
| Creep-rupture time, Ta-10W at 2000 °F under 52200 psi | 1.5 h11 |
| Oxygen, maximum residual, Grade I | < 150 ppm17 |
| Tungsten content, Ta-10W (ATI typical composition)Range printed in a manufacturer datasheet | 9 to 11 wt% |
| Tungsten content, UNS R05255 (Ta-10W), ASTM B708 | 9 to 11 wt%18 |
| Tungsten content, UNS R05252 (Ta-2.5W), ASTM B708 | 2 to 3.5 wt%19 |
| ASTM B708 minimum tensile strength, UNS R05255 (Ta-10W) | > 481 MPa20 |
| ASTM B708 minimum yield strength, UNS R05255 (Ta-10W) | > 414 MPa21 |
| ASTM B708 minimum elongation, UNS R05255 (Ta-10W) | > 15 %22 |
| ASTM B708 minimum tensile strength, UNS R05252 (Ta-2.5W) | > 276 MPa23 |
| ASTM B708 minimum yield strength, UNS R05252 (Ta-2.5W) | > 193 MPa24 |
| ASTM B708 minimum elongation, UNS R05252 (Ta-2.5W) | > 20 %25 |
| Modulus of elasticity, Ta97.5/W2.5 (Ta-2.5W) rod | 186 GPa30 |
| Tensile strength, Ta97.5/W2.5 (Ta-2.5W) rod | 240 to 310 MPa32 |
Why choose it, and why not
Good for
- Hot structural and nozzle parts: ATI names nozzles, inserts and structural material for elevated-temperature aerospace use.
- Corrosion resistance: ATI says the alloy has excellent corrosion resistance in many media, with no rate given.
Watch out for
- Oxidation in air: the lives in the sources are for coated coupons, 45 hours at 2000 °F in one NASA test.
- Density: 16.9 g/cm3 for Ta-10W, so it is heavy compared with the structural metals in this collection.
- Strength depends on form and temper: the ATI figures are typical values for recrystallized sheet, and the ASTM figures are minimums.
- No space-environment result for either grade was found in the sources read; the 1966 NASA work was a ground test.
Tantalum-tungsten alloys are strong, corrosion-resistant metals for hot parts. Ta-10W is the stronger grade, at 481 MPa minimum tensile strength, and is heavy at 16.9 g/cm3. In air they need a coating, and the sources we hold give coated lives only, not a life for bare metal.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| UNS | R05255, R05252 |
| ASTM | B708 (plate, sheet and strip) |
| Trade name | Tantaloy 60, Tantaloy 63, ATI Ta10W |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, Ta-10W (ATI Ta10W) | Typical value printed in a manufacturer datasheet; the sheet says its data are typical and not maximum or minimum values | grade Ta-10W (ATI Ta10W, tantalum-10% tungsten)unit in source 0.608 lbs/in3temperature not stated | — |
| 2 | Melting point, Ta-10W (ATI Ta10W) | Typical value printed in a manufacturer datasheet | grade Ta-10Wunit in source 5495°F | — |
| 3 | Ingot hardness, Ta-10W | Range printed in a manufacturer datasheet (unit as printed, BHN) | condition ingotload 3000 kg | — |
| 4 | Tensile strength at room temperature, recrystallized sheet | Nominal range printed in a manufacturer datasheet (typical data) | grade Ta-10Wform recrystallized sheet, 0.040 to 0.045 in thicktemperature room temperature | — |
| 5 | Yield strength at room temperature, recrystallized sheet | Nominal range printed in a manufacturer datasheet (typical data) | grade Ta-10Wform recrystallized sheet, 0.040 to 0.045 in thicktemperature room temperature | — |
| 6 | Elongation at room temperature, recrystallized sheet | Nominal range printed in a manufacturer datasheet | grade Ta-10Wform recrystallized sheet, 0.040 to 0.045 in thickgauge length 1 in | — |
| 7 | Tensile strength at 2600 °F, recrystallized sheet | Nominal range printed in a manufacturer datasheet | grade Ta-10Wform recrystallized sheet, 0.040 to 0.045 in thicktemperature 2600 °F | — |
| 8 | Tensile strength at 3000 °F, recrystallized sheet | Nominal range printed in a manufacturer datasheet | grade Ta-10Wform recrystallized sheet, 0.040 to 0.045 in thicktemperature 3000 °F | — |
| 9 | Tensile strength at 2000 °F, stress-relieved sheet | Single nominal value printed in a manufacturer datasheet; tested at 0.05 in/in/min | grade Ta-10Wform stress-relieved sheet, 0.040 to 0.045 in thick, stress relieved 3 hours at 2250 °Ftemperature 2000 °F | — |
| 10 | Yield strength at 2000 °F, stress-relieved sheet | Single nominal value printed in a manufacturer datasheet | grade Ta-10Wform stress-relieved sheet, 0.040 to 0.045 in thick, stress relieved 3 hours at 2250 °Ftemperature 2000 °F | — |
| 11 | Creep-rupture time, Ta-10W at 2000 °F under 52200 psi | Creep-rupture point printed in a manufacturer datasheet table | grade Ta-10Wtemperature 2000 °Fstress 52,200 psi | — |
| 12 | Thermal expansion strain, Ta-10W from room temperature to 5250 °F | Strain printed in a manufacturer datasheet table; the source gives strain, not a coefficient in ppm/K, so no coefficient is calculated here | grade Ta-10Wtemperature 5250 °Freference room temperaturequantity delta L / L (strain, not a coefficient) | — |
| 13 | Thermal conductivity, Ta-10W at 1700 K | Value printed in a manufacturer datasheet in cal/(cm2)(sec)(K/cm); not converted to W/(m·K) here | grade Ta-10Wtemperature 1700 Kunit in source cal/(cm2)(sec)(K/cm) | — |
| 14 | Thermal conductivity, Ta-10W at 3200 K | Value printed in a manufacturer datasheet in cal/(cm2)(sec)(K/cm); not converted to W/(m·K) here | grade Ta-10Wtemperature 3200 Kunit in source cal/(cm2)(sec)(K/cm) | — |
| 15 | Cyclic coating life, silicon coating on Ta-10W at 2200 °F | Average coating life printed in a manufacturer datasheet table (cyclic test) | coating 100 Si (atomic percent)substrate Ta-10Wtest cyclic life test on coated Ta-10Wtemperature 2200 °F | — |
| 16 | Cyclic coating life, 50Sn-50Al coating on Ta-10W at 2200 °F | Average coating life printed in a manufacturer datasheet table (cyclic test) | coating 50 Sn-50 Al (weight percent)substrate Ta-10Wtest cyclic life test on coated Ta-10Wtemperature 2200 °F | — |
| 17 | Oxygen, maximum residual, Grade I | Maximum printed in a manufacturer datasheet table | grade Ta-10W, Grade Ibasis maximum residual | — |
| 18 | Tungsten content, UNS R05255 (Ta-10W), ASTM B708 | Range printed in the chemical composition table of a supplier summary of ASTM B708 | grade UNS R05255 (Ta-10W)standard ASTM B708 plate, sheet and strip | — |
| 19 | Tungsten content, UNS R05252 (Ta-2.5W), ASTM B708 | Range printed in the chemical composition table of a supplier summary of ASTM B708 | grade UNS R05252 (Ta-2.5W)standard ASTM B708 plate, sheet and strip | — |
| 20 | ASTM B708 minimum tensile strength, UNS R05255 (Ta-10W) | Specification minimum printed in a supplier summary of ASTM B708 | grade UNS R05255 (Ta-10W)standard ASTM B708 plate, sheet and stripbasis minimum, printed as 70,000 psi (481 MPa) | — |
| 21 | ASTM B708 minimum yield strength, UNS R05255 (Ta-10W) | Specification minimum printed in a supplier summary of ASTM B708 | grade UNS R05255 (Ta-10W)standard ASTM B708 plate, sheet and stripbasis 0.2% offset minimum, printed as 60,000 psi (414 MPa) | — |
| 22 | ASTM B708 minimum elongation, UNS R05255 (Ta-10W) | Specification minimum printed in a supplier summary of ASTM B708 | grade UNS R05255 (Ta-10W)standard ASTM B708 plate, sheet and strip | — |
| 23 | ASTM B708 minimum tensile strength, UNS R05252 (Ta-2.5W) | Specification minimum printed in a supplier summary of ASTM B708 | grade UNS R05252 (Ta-2.5W)standard ASTM B708 plate, sheet and stripbasis minimum, printed as 40,000 psi (276 MPa) | — |
| 24 | ASTM B708 minimum yield strength, UNS R05252 (Ta-2.5W) | Specification minimum printed in a supplier summary of ASTM B708 | grade UNS R05252 (Ta-2.5W)standard ASTM B708 plate, sheet and stripbasis 0.2% offset minimum, printed as 28,000 psi (193 MPa) | — |
| 25 | ASTM B708 minimum elongation, UNS R05252 (Ta-2.5W) | Specification minimum printed in a supplier summary of ASTM B708 | grade UNS R05252 (Ta-2.5W)standard ASTM B708 plate, sheet and strip | — |
| 26 | Density, Ta97.5/W2.5 (Ta-2.5W) rod | Value printed on a distributor's product page (Physical Properties) | grade Ta97.5/W2.5 (Ta-2.5W)product rod, 2.5 mm diameter, as drawn | — |
| 27 | Melting point, Ta97.5/W2.5 (Ta-2.5W) rod | Value printed on a distributor's product page (Thermal Properties) | grade Ta97.5/W2.5 (Ta-2.5W)product rod, 2.5 mm diameter, as drawn | — |
| 28 | Specific heat, Ta97.5/W2.5 (Ta-2.5W) rod | Value printed on a distributor's product page (Thermal Properties) | grade Ta97.5/W2.5 (Ta-2.5W)temperature 23 °Cunit in source J K-1 kg-1 | — |
| 29 | Thermal conductivity, Ta97.5/W2.5 (Ta-2.5W) rod | Value printed on a distributor's product page (Thermal Properties) | grade Ta97.5/W2.5 (Ta-2.5W)temperature 23 °Cunit in source W m-1 K-1 | — |
| 30 | Modulus of elasticity, Ta97.5/W2.5 (Ta-2.5W) rod | Value printed on a distributor's product page (Mechanical Properties) | grade Ta97.5/W2.5 (Ta-2.5W)product rod, 2.5 mm diameter, as drawn | — |
| 31 | Vickers hardness, Ta97.5/W2.5 (Ta-2.5W) rod | Range printed on a distributor's product page (Mechanical Properties) | grade Ta97.5/W2.5 (Ta-2.5W)temper as drawn | — |
| 32 | Tensile strength, Ta97.5/W2.5 (Ta-2.5W) rod | Range printed on a distributor's product page (Mechanical Properties); one product form only | grade Ta97.5/W2.5 (Ta-2.5W)product rod, 2.5 mm diameter, as drawn | — |
| 33 | Cyclic oxidation life, coated Ta-10W coupon at 2000 °F | Time to failure printed in a NASA Langley table of oxidation tests | coating Sn-27Al-5.3Mo coating as printed in Table Isubstrate Ta-10W feasibility coupontest 1.0-hour cycles in air at 760 mm Hgtemperature 2000 °F | — |
| 34 | Substrate thickness loss, coated Ta-10W coupon at 2000 °F | Substrate thickness loss printed in a NASA Langley table of oxidation tests | coating Sn-27Al-5.3Mo coating as printed in Table Isubstrate Ta-10W feasibility coupontest 1.0-hour cycles in air at 760 mm Hgtemperature 2000 °F | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Hot air, coated Ta-10W | moderate | A coating protects Ta-10W in hot air for a limited time: about 45 hours at 2000 °F in a NASA test.1 |
| Aqueous and chemical media | low | The datasheet calls the corrosion resistance excellent in many media, with no rate given.2 |
| Low Earth orbit (atomic oxygen) | not rated | No atomic-oxygen result for either Ta-W alloy was found in the sources we hold.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Hot air, coated Ta-10W | In a 1966 NASA Langley study, coated Ta-10W coupons with a Sn-27Al-5.3Mo coating failed after 45 hours of 1-hour cycles in air at 2000 °F, after losing 0.0009 inch of substrate. ATI's cyclic tests of coated Ta-10W give 50 hours at 2200 °F for a silicon coating and 290 hours at 2200 °F for a 50Sn-50Al coating (weight percent). The sources give coated lives only, not a life for bare Ta-10W in air. | basis coated coupons only; the NASA test used 1.0-hour cycles in air at 760 mm Hgnote two different test programmes; lives are not directly comparable |
| 2 | Aqueous and chemical media | ATI says the alloy has excellent corrosion resistance in many media and is available in all commercial mill product forms. It gives no corrosion rate for a named medium in the datasheet we read. | basis qualitative statement in a manufacturer datasheet; no test medium or rate given |
| 3 | Low Earth orbit (atomic oxygen) | Not found in any source we hold. See gaps. | basis no source read in this run |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The sources we hold describe the hazards of tantalum metal in general, not of the alloy. Bulk metal is the lower-risk form; fine powder is the concern.
- Bulk form
- PubChem says tantalum metal 'does not meet GHS hazard criteria for 44% (200 of 455) of reports', and it lists H228 and H252 only where codes were given.
- Powder
- PubChem says metallic tantalum powder 'presents a fire...hazard' and that bulk tantalum is 'much less reactive' than the powder.
If the coating fails
These results come from laboratory oxidation tests on coated coupons, not from field or flight use.
- Coated coupon in air
- In a 1966 NASA Langley test, a coated Ta-10W coupon failed after 45 hours of 1-hour cycles at 2000 °F, after losing 0.0009 inch of substrate.
- Silicon coating
- In ATI's cyclic tests, a silicon coating on Ta-10W lasted 50 hours at 2200 °F.
- Strength when hot
- Recrystallized Ta-10W sheet falls from 80,000 to 95,000 psi ultimate tensile strength at room temperature to 36,200 to 37,100 psi at 2600 °F (ATI nominal values).
Handling and storage
- Welding
- ATI says welded Ta-10W has essentially the same properties as the base metal, and names electron-beam and inert-gas fusion welding.
- Specify the form
- The ASTM B708 minimums apply to plate, sheet and strip. The ATI values are typical data for recrystallized sheet, and the Goodfellow values are for an as-drawn rod, so state the form and temper when you specify strength.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Coating breakdown in hot airmoderate severity | 1-hour cycles in air at 2000 °FA coated Ta-10W coupon failed after 45 hours, with 0.0009 inch of substrate lost (1966 NASA Langley test). |
| Loss of tensile strength when hotmoderate severity | Recrystallized Ta-10W sheet at 2600 °FUltimate tensile strength falls to 36,200 to 37,100 psi, against 80,000 to 95,000 psi at room temperature (ATI nominal values). |
| Ignition of fine powdermoderate severity | Fine tantalum powder in airPubChem reports that powder can ignite spontaneously in air. The bulk alloy is described as much less reactive; no bulk ignition test was found. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Substrate thickness of coated sheet | In the 1966 NASA Langley study, metallurgical examination of coated coupons showed that solid-state diffusion between coating and substrate reduced the thickness of the Ta-10W substrate. |
Handling and storage
- ATI says the properties of properly welded Ta-10W are essentially the same as those of the base metal; the datasheet names electron-beam and inert-gas fusion welding.
- The Ta-10W and Ta-2.5W minimums in ASTM B708 apply to plate, sheet and strip; the datasheet values are typical and are for a different product form, so state the form and temper when you specify strength.
- PubChem advises that tantalum metal be kept separate from strong oxidants and halogens, and that open flames, arcs and sparks be avoided where tantalum powder is handled.
Mitigations
- Coatings for hot air: ATI and the 1966 NASA study both tested coatings on Ta-10W, and their lives are the figures recorded under corrosion.
Supply and geography
How common the raw materials are and where they come from.
Tantalum
USGS: identified world tantalum resources are 'considered adequate to supply projected needs', most of them in Australia, Brazil, Canada and China.
- Top producers (2025)
- Congo (Kinshasa) 52%, Rwanda 16%, Nigeria 15.6%, Brazil 7.6%, China 3.2%, Australia 2%
- Recycling
- USGS: tantalum was recycled mostly from new scrap, and the amount recycled was not available; recycling 'may account for as much as 30%' of consumption by domestic primary processors.
- Substitutes
- USGS: hafnium, iridium, molybdenum, niobium, rhenium, and tungsten can substitute for tantalum in high-temperature applications, with performance loss or higher costs.
Tungsten (alloying element)
Not given in the USGS tungsten summary we read.
- Top producers (2025)
- China 78.8%, Vietnam 3.5%, Kazakhstan 2.8%, Russia 2.4%, Korea North 2.4%
- Recycling
- USGS: the estimated quantity of secondary tungsten produced in 2025 was withheld to avoid disclosing company proprietary data.
- Substitutes
- USGS: molybdenum can substitute for certain tungsten mill products, and depleted uranium or lead can substitute for tungsten or tungsten alloys where high density or radiation shielding is required.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: tantalum-tungsten-alloys
spore_version: 0.2
family: tantalum-alloys
name: Tantalum-tungsten alloys (Ta-2.5W and Ta-10W)
abbreviation: Ta-W
role: high-temperature structural metal
category: metals
type: refractory-metals
summary: |
Tantalum-tungsten alloys are refractory metals. Ta-10W (UNS R05255) contains 9 to 11 wt% tungsten, and Ta-2.5W (UNS R05252) contains 2.0 to 3.5 wt% tungsten. ATI gives a density of 16.9 g/cm3 and a melting point of 3035 °C for Ta-10W. The ASTM B708 minimum tensile strength for Ta-10W plate, sheet and strip is 481 MPa, and the sources we hold give no oxidation-resistance figure for the bare alloy in air, only coated-coupon test lives.
best_for: Hot structural and nozzle parts that need ductility and corrosion resistance at elevated temperature, with a protective coating where the part sees hot air
weakest_at: 'Weight (16.9 g/cm3 for Ta-10W) and oxidation in hot air: the sources give coating lives, not uncoated lives'
identity:
formula: Tantalum alloyed with 9.0 to 11.0 wt% tungsten (Ta-10W, UNS R05255) or 2.0 to 3.5 wt% tungsten (Ta-2.5W, UNS R05252), balance tantalum
crystal_system: body-centred cubic
source: wikipedia-taw
where: Mechanical properties section (crystal structure, substitutional solid solution of tungsten in tantalum); composition from the ASTM B708 composition table on the gsalloy page
designations:
- system: UNS
code: R05255
source: gsalloy-astm-b708
where: 'Technical Specifications table, grade row: UNS R05255, Ta alloy, 90% Ta – 10% W, Ta-10W, Tantaloy 60'
- system: UNS
code: R05252
source: gsalloy-astm-b708
where: 'Technical Specifications table, grade row: UNS R05252, Ta alloy, 97.5% Ta – 2.5% W, Ta-2.5W, Tantaloy 63'
- system: ASTM
code: B708
note: plate, sheet and strip
source: gsalloy-astm-b708
where: Page title and Technical Specifications table, Standard row
- system: Trade name
code: Tantaloy 60
source: gsalloy-astm-b708
where: Grade row for UNS R05255
- system: Trade name
code: Tantaloy 63
source: gsalloy-astm-b708
where: Grade row for UNS R05252
- system: Trade name
code: ATI Ta10W
source: ati-ta10w
where: Title block on each page of the datasheet
tags:
environments: []
stresses:
- extreme-heat
applications:
- propulsion-and-tanks
- heat-shields
- structures
properties:
- benchmark: density
label: Density, Ta-10W (ATI Ta10W)
value: 16.9
unit: g/cm3
scope: material
conditions:
grade: Ta-10W (ATI Ta10W, tantalum-10% tungsten)
unit_in_source: 0.608 lbs/in3
temperature: not stated
method: Typical value printed in a manufacturer datasheet; the sheet says its data are typical and not maximum or minimum values
status: ground
source: ati-ta10w
where: Table 2, Physical Properties, row Density
- benchmark: melting_point
label: Melting point, Ta-10W (ATI Ta10W)
value: 3035
unit: °C
scope: material
conditions:
grade: Ta-10W
unit_in_source: 5495°F
method: Typical value printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Table 2, Physical Properties, row Melting Point
- benchmark: recrystallization_temperature
label: Recrystallization temperature, Ta-10W
value: 2400
value_high: 2800
bound: range
unit: °F
scope: material
conditions:
grade: Ta-10W
treatment: one hour
method: Range printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Table 2, Physical Properties, row Recrystallization Temperature
- benchmark: hardness_brinell
label: Ingot hardness, Ta-10W
value: 185
value_high: 210
bound: range
unit: BHN
scope: material
conditions:
condition: ingot
load: 3000 kg
method: Range printed in a manufacturer datasheet (unit as printed, BHN)
status: ground
source: ati-ta10w
where: Table 2, Physical Properties, row Hardness
- benchmark: ultimate_tensile_strength
label: Tensile strength at room temperature, recrystallized sheet
value: 80000
value_high: 95000
bound: range
unit: psi
scope: material
conditions:
grade: Ta-10W
form: recrystallized sheet, 0.040 to 0.045 in thick
temperature: room temperature
method: Nominal range printed in a manufacturer datasheet (typical data)
status: ground
source: ati-ta10w
where: Table 3, Nominal Tensile Properties, row R.T., column UTS-PSI
- benchmark: yield_strength
label: Yield strength at room temperature, recrystallized sheet
value: 70000
value_high: 89000
bound: range
unit: psi
scope: material
conditions:
grade: Ta-10W
form: recrystallized sheet, 0.040 to 0.045 in thick
temperature: room temperature
method: Nominal range printed in a manufacturer datasheet (typical data)
status: ground
source: ati-ta10w
where: Table 3, row R.T., column YTS-PSI
- benchmark: elongation
label: Elongation at room temperature, recrystallized sheet
value: 20
value_high: 40
bound: range
unit: '%'
scope: material
conditions:
grade: Ta-10W
form: recrystallized sheet, 0.040 to 0.045 in thick
gauge_length: 1 in
method: Nominal range printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Table 3, row R.T., column %Elongation in 1 inch
- benchmark: ultimate_tensile_strength
label: Tensile strength at 2600 °F, recrystallized sheet
value: 36200
value_high: 37100
bound: range
unit: psi
scope: material
conditions:
grade: Ta-10W
form: recrystallized sheet, 0.040 to 0.045 in thick
temperature: 2600 °F
method: Nominal range printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Table 3, row 2600, column UTS-PSI
- benchmark: ultimate_tensile_strength
label: Tensile strength at 3000 °F, recrystallized sheet
value: 15000
value_high: 16000
bound: range
unit: psi
scope: material
conditions:
grade: Ta-10W
form: recrystallized sheet, 0.040 to 0.045 in thick
temperature: 3000 °F
method: Nominal range printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Table 3, row 3000, column UTS-PSI
- benchmark: ultimate_tensile_strength
label: Tensile strength at 2000 °F, stress-relieved sheet
value: 60700
unit: psi
scope: material
conditions:
grade: Ta-10W
form: stress-relieved sheet, 0.040 to 0.045 in thick, stress relieved 3 hours at 2250 °F
temperature: 2000 °F
method: Single nominal value printed in a manufacturer datasheet; tested at 0.05 in/in/min
status: ground
source: ati-ta10w
where: Table 4, Nominal Tensile Properties, row 2000, column UTS-PSI
- benchmark: yield_strength
label: Yield strength at 2000 °F, stress-relieved sheet
value: 55100
unit: psi
scope: material
conditions:
grade: Ta-10W
form: stress-relieved sheet, 0.040 to 0.045 in thick, stress relieved 3 hours at 2250 °F
temperature: 2000 °F
method: Single nominal value printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Table 4, row 2000, column YTS-PSI
- benchmark: creep_rupture_time
label: Creep-rupture time, Ta-10W at 2000 °F under 52200 psi
value: 1.5
unit: h
scope: material
conditions:
grade: Ta-10W
temperature: 2000 °F
stress: 52,200 psi
method: Creep-rupture point printed in a manufacturer datasheet table
status: ground
source: ati-ta10w
where: Table 5, Creep-Rupture Properties, 2000 °F group, stress 52,200 psi
- benchmark: thermal_strain
label: Thermal expansion strain, Ta-10W from room temperature to 5250 °F
value: 0.0222
unit: '-'
scope: material
conditions:
grade: Ta-10W
temperature: 5250 °F
reference: room temperature
quantity: delta L / L (strain, not a coefficient)
method: Strain printed in a manufacturer datasheet table; the source gives strain, not a coefficient in ppm/K, so no coefficient is calculated here
status: ground
source: ati-ta10w
where: Table 6, Thermal Expansion, row 5250
- benchmark: thermal_conductivity
label: Thermal conductivity, Ta-10W at 1700 K
value: 0.135
unit: cal/(cm2 sec K/cm)
scope: material
conditions:
grade: Ta-10W
temperature: 1700 K
unit_in_source: cal/(cm2)(sec)(K/cm)
method: Value printed in a manufacturer datasheet in cal/(cm2)(sec)(K/cm); not converted to W/(m·K) here
status: ground
source: ati-ta10w
where: Table 7, Thermal Conductivity, row 1700
- benchmark: thermal_conductivity
label: Thermal conductivity, Ta-10W at 3200 K
value: 0.082
unit: cal/(cm2 sec K/cm)
scope: material
conditions:
grade: Ta-10W
temperature: 3200 K
unit_in_source: cal/(cm2)(sec)(K/cm)
method: Value printed in a manufacturer datasheet in cal/(cm2)(sec)(K/cm); not converted to W/(m·K) here
status: ground
source: ati-ta10w
where: Table 7, Thermal Conductivity, row 3200
- benchmark: coating_life_cyclic
label: Cyclic coating life, silicon coating on Ta-10W at 2200 °F
value: 50
unit: h
scope: material
conditions:
coating: 100 Si (atomic percent)
substrate: Ta-10W
test: cyclic life test on coated Ta-10W
temperature: 2200 °F
method: Average coating life printed in a manufacturer datasheet table (cyclic test)
status: ground
source: ati-ta10w
where: Table 8, Cyclic Life-Test Data on Coated Tantalum-10% Tungsten, row 100 Si, column 2200°F
- benchmark: coating_life_cyclic
label: Cyclic coating life, 50Sn-50Al coating on Ta-10W at 2200 °F
value: 290
unit: h
scope: material
conditions:
coating: 50 Sn-50 Al (weight percent)
substrate: Ta-10W
test: cyclic life test on coated Ta-10W
temperature: 2200 °F
method: Average coating life printed in a manufacturer datasheet table (cyclic test)
status: ground
source: ati-ta10w
where: Table 8, row 50 Sn-50 Al, column 2200°F
- benchmark: residual_oxygen
label: Oxygen, maximum residual, Grade I
value: 150
bound: upper
unit: ppm
scope: material
conditions:
grade: Ta-10W, Grade I
basis: maximum residual
method: Maximum printed in a manufacturer datasheet table
status: ground
source: ati-ta10w
where: Table 1, Maximum Residuals, row Oxygen
- benchmark: tungsten_content
label: Tungsten content, Ta-10W (ATI typical composition)
value: 9
value_high: 11
bound: range
unit: wt%
scope: material
conditions:
grade: Ta-10W
basis: typical composition, balance tantalum and residuals
method: Range printed in a manufacturer datasheet
status: ground
source: ati-ta10w
where: Section II, Typical Composition
- benchmark: tungsten_content
label: Tungsten content, UNS R05255 (Ta-10W), ASTM B708
value: 9
value_high: 11
bound: range
unit: wt%
scope: material
conditions:
grade: UNS R05255 (Ta-10W)
standard: ASTM B708 plate, sheet and strip
method: Range printed in the chemical composition table of a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Chemical Composition table, column UNS R05255, row Tungsten (W)
- benchmark: tungsten_content
label: Tungsten content, UNS R05252 (Ta-2.5W), ASTM B708
value: 2
value_high: 3.5
bound: range
unit: wt%
scope: material
conditions:
grade: UNS R05252 (Ta-2.5W)
standard: ASTM B708 plate, sheet and strip
method: Range printed in the chemical composition table of a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Chemical Composition table, column UNS R05252, row Tungsten (W)
- benchmark: ultimate_tensile_strength
label: ASTM B708 minimum tensile strength, UNS R05255 (Ta-10W)
value: 481
bound: lower
unit: MPa
scope: material
conditions:
grade: UNS R05255 (Ta-10W)
standard: ASTM B708 plate, sheet and strip
basis: minimum, printed as 70,000 psi (481 MPa)
method: Specification minimum printed in a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table, row R05255, column Ultimate Tensile Strength (min)
- benchmark: yield_strength
label: ASTM B708 minimum yield strength, UNS R05255 (Ta-10W)
value: 414
bound: lower
unit: MPa
scope: material
conditions:
grade: UNS R05255 (Ta-10W)
standard: ASTM B708 plate, sheet and strip
basis: 0.2% offset minimum, printed as 60,000 psi (414 MPa)
method: Specification minimum printed in a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table, row R05255, column Yield Strength (min)
- benchmark: elongation
label: ASTM B708 minimum elongation, UNS R05255 (Ta-10W)
value: 15
bound: lower
unit: '%'
scope: material
conditions:
grade: UNS R05255 (Ta-10W)
standard: ASTM B708 plate, sheet and strip
method: Specification minimum printed in a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table, row R05255, column Elongation (min)
- benchmark: ultimate_tensile_strength
label: ASTM B708 minimum tensile strength, UNS R05252 (Ta-2.5W)
value: 276
bound: lower
unit: MPa
scope: material
conditions:
grade: UNS R05252 (Ta-2.5W)
standard: ASTM B708 plate, sheet and strip
basis: minimum, printed as 40,000 psi (276 MPa)
method: Specification minimum printed in a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table, row R05252, column Ultimate Tensile Strength (min)
- benchmark: yield_strength
label: ASTM B708 minimum yield strength, UNS R05252 (Ta-2.5W)
value: 193
bound: lower
unit: MPa
scope: material
conditions:
grade: UNS R05252 (Ta-2.5W)
standard: ASTM B708 plate, sheet and strip
basis: 0.2% offset minimum, printed as 28,000 psi (193 MPa)
method: Specification minimum printed in a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table, row R05252, column Yield Strength (min)
- benchmark: elongation
label: ASTM B708 minimum elongation, UNS R05252 (Ta-2.5W)
value: 20
bound: lower
unit: '%'
scope: material
conditions:
grade: UNS R05252 (Ta-2.5W)
standard: ASTM B708 plate, sheet and strip
method: Specification minimum printed in a supplier summary of ASTM B708
status: ground
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table, row R05252, column Elongation (min)
- benchmark: density
label: Density, Ta97.5/W2.5 (Ta-2.5W) rod
value: 16.66
unit: g/cm3
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
product: rod, 2.5 mm diameter, as drawn
method: Value printed on a distributor's product page (Physical Properties)
status: ground
source: goodfellow-ta-w-rod
where: Physical Properties, Density
- benchmark: melting_point
label: Melting point, Ta97.5/W2.5 (Ta-2.5W) rod
value: 3014
unit: °C
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
product: rod, 2.5 mm diameter, as drawn
method: Value printed on a distributor's product page (Thermal Properties)
status: ground
source: goodfellow-ta-w-rod
where: Thermal Properties, Melting point
- benchmark: specific_heat
label: Specific heat, Ta97.5/W2.5 (Ta-2.5W) rod
value: 141
unit: J/(kg·K)
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
temperature: 23 °C
unit_in_source: J K-1 kg-1
method: Value printed on a distributor's product page (Thermal Properties)
status: ground
source: goodfellow-ta-w-rod
where: Thermal Properties, Specific heat
- benchmark: thermal_conductivity
label: Thermal conductivity, Ta97.5/W2.5 (Ta-2.5W) rod
value: 55
unit: W/(m·K)
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
temperature: 23 °C
unit_in_source: W m-1 K-1
method: Value printed on a distributor's product page (Thermal Properties)
status: ground
source: goodfellow-ta-w-rod
where: Thermal Properties, Thermal conductivity
- benchmark: elastic_modulus
label: Modulus of elasticity, Ta97.5/W2.5 (Ta-2.5W) rod
value: 186
unit: GPa
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
product: rod, 2.5 mm diameter, as drawn
method: Value printed on a distributor's product page (Mechanical Properties)
status: ground
source: goodfellow-ta-w-rod
where: Mechanical Properties, Modulus of elasticity
- benchmark: hardness_vickers
label: Vickers hardness, Ta97.5/W2.5 (Ta-2.5W) rod
value: 115
value_high: 160
bound: range
unit: kgf/mm2
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
temper: as drawn
method: Range printed on a distributor's product page (Mechanical Properties)
status: ground
source: goodfellow-ta-w-rod
where: Mechanical Properties, Hardness - Vickers
- benchmark: ultimate_tensile_strength
label: Tensile strength, Ta97.5/W2.5 (Ta-2.5W) rod
value: 240
value_high: 310
bound: range
unit: MPa
scope: material
conditions:
grade: Ta97.5/W2.5 (Ta-2.5W)
product: rod, 2.5 mm diameter, as drawn
method: Range printed on a distributor's product page (Mechanical Properties); one product form only
status: ground
source: goodfellow-ta-w-rod
where: Mechanical Properties, Tensile strength
- benchmark: coating_life_cyclic
label: Cyclic oxidation life, coated Ta-10W coupon at 2000 °F
value: 45
unit: h
scope: material
conditions:
coating: Sn-27Al-5.3Mo coating as printed in Table I
substrate: Ta-10W feasibility coupon
test: 1.0-hour cycles in air at 760 mm Hg
temperature: 2000 °F
method: Time to failure printed in a NASA Langley table of oxidation tests
status: ground
source: nasa-1966-ta10w
where: Table I, Results of oxidation tests on Ta-10W feasibility specimens, row Coupon, 1.0-hour cyclic, 2000
- benchmark: substrate_thickness_loss
label: Substrate thickness loss, coated Ta-10W coupon at 2000 °F
value: 0.0009
unit: inch
scope: material
conditions:
coating: Sn-27Al-5.3Mo coating as printed in Table I
substrate: Ta-10W feasibility coupon
test: 1.0-hour cycles in air at 760 mm Hg
temperature: 2000 °F
method: Substrate thickness loss printed in a NASA Langley table of oxidation tests
status: ground
source: nasa-1966-ta10w
where: Table I, row Coupon, 1.0-hour cyclic, 2000, column Substrate thickness loss
corrosion:
- environment: Hot air, coated Ta-10W
headline: 'A coating protects Ta-10W in hot air for a limited time: about 45 hours at 2000 °F in a NASA test.'
effect: In a 1966 NASA Langley study, coated Ta-10W coupons with a Sn-27Al-5.3Mo coating failed after 45 hours of 1-hour cycles in air at 2000 °F, after losing 0.0009 inch of substrate. ATI's cyclic tests of coated Ta-10W give 50 hours at 2200 °F for a silicon coating and 290 hours at 2200 °F for a 50Sn-50Al coating (weight percent). The sources give coated lives only, not a life for bare Ta-10W in air.
rating: moderate
conditions:
basis: coated coupons only; the NASA test used 1.0-hour cycles in air at 760 mm Hg
note: two different test programmes; lives are not directly comparable
source: nasa-1966-ta10w
where: Table I, row Coupon, 1.0-hour cyclic, 2000; ATI Table 8, rows 100 Si and 50 Sn-50 Al, column 2200°F
- environment: Aqueous and chemical media
headline: The datasheet calls the corrosion resistance excellent in many media, with no rate given.
effect: ATI says the alloy has excellent corrosion resistance in many media and is available in all commercial mill product forms. It gives no corrosion rate for a named medium in the datasheet we read.
rating: low
conditions:
basis: qualitative statement in a manufacturer datasheet; no test medium or rate given
source: ati-ta10w
where: Section I, Scope
- environment: Low Earth orbit (atomic oxygen)
headline: No atomic-oxygen result for either Ta-W alloy was found in the sources we hold.
effect: Not found in any source we hold. See gaps.
rating: unknown
conditions:
basis: no source read in this run
source: pubchem-ta
where: 'Not applicable: no source read in this run gives an atomic-oxygen result'
risks:
hazards:
- text: 'PubChem''s GHS summary for tantalum metal (CID 23956) says the substance ''does not meet GHS hazard criteria for 44% (200 of 455) of reports''. Where codes were given it lists ''H228 (56%): Flammable solid'' and ''H252 (37.8%): Self-heating in large quantities; may catch fire''. The summary is for tantalum metal, not for the tungsten-containing alloy.'
ghs:
- H228
- H252
source: pubchem-ta
where: Safety and Hazards, GHS Classification
- text: PubChem says that 'Metallic tantalum powder presents a fire...hazard, although not as serious as that of other metals' and that tantalum 'in bulk form (bar, sheet, etc.) is much less reactive than it is in powdered' form.
ghs: []
source: pubchem-ta
where: Safety and Hazards, Fire Potential and Reactivity Profile
failure_risks:
- mode: Coating breakdown in hot air
trigger: 1-hour cycles in air at 2000 °F
consequence: A coated Ta-10W coupon failed after 45 hours, with 0.0009 inch of substrate lost (1966 NASA Langley test).
severity: moderate
source: nasa-1966-ta10w
where: Table I, row Coupon, 1.0-hour cyclic, 2000
- mode: Loss of tensile strength when hot
trigger: Recrystallized Ta-10W sheet at 2600 °F
consequence: Ultimate tensile strength falls to 36,200 to 37,100 psi, against 80,000 to 95,000 psi at room temperature (ATI nominal values).
severity: moderate
source: ati-ta10w
where: Table 3, rows R.T. and 2600
- mode: Ignition of fine powder
trigger: Fine tantalum powder in air
consequence: PubChem reports that powder can ignite spontaneously in air. The bulk alloy is described as much less reactive; no bulk ignition test was found.
severity: moderate
source: pubchem-ta
where: Safety and Hazards, Fire Potential; Reactivity Profile
side_effects:
- text: In the 1966 NASA Langley study, metallurgical examination of coated coupons showed that solid-state diffusion between coating and substrate reduced the thickness of the Ta-10W substrate.
affects: Substrate thickness of coated sheet
source: nasa-1966-ta10w
where: Results, metallurgical examinations of coated coupons
handling:
- text: ATI says the properties of properly welded Ta-10W are essentially the same as those of the base metal; the datasheet names electron-beam and inert-gas fusion welding.
source: ati-ta10w
where: Section V, Weldability
- text: The Ta-10W and Ta-2.5W minimums in ASTM B708 apply to plate, sheet and strip; the datasheet values are typical and are for a different product form, so state the form and temper when you specify strength.
source: gsalloy-astm-b708
where: Mechanical Properties and Hardness table; Type row
- text: PubChem advises that tantalum metal be kept separate from strong oxidants and halogens, and that open flames, arcs and sparks be avoided where tantalum powder is handled.
source: pubchem-ta
where: Handling and Storage, Safe Storage; Preventive Measures
mitigations:
- text: 'Coatings for hot air: ATI and the 1966 NASA study both tested coatings on Ta-10W, and their lives are the figures recorded under corrosion.'
source: nasa-1966-ta10w
where: Table I; see also ATI Table 8
uses:
- application: propulsion-and-tanks
device: Rocket nozzles, inserts and directional devices (aerospace, high temperature)
example: ATI says Ta10W was developed for elevated-temperature use, with applications in the high-temperature aerospace field including nozzles, inserts, directional devices and structural materials.
source: ati-ta10w
where: Section I, Scope
- application: heat-shields
device: Heat-shield panels (ground oxidation tests, NASA Langley 1966)
example: A 1966 NASA Langley study tested coated Ta-10W sheet for heat-shield use and built corrugated heat-shield panels from Ta-10W sheet. The work was ground testing, not flight.
source: nasa-1966-ta10w
where: Introduction and heat-shield design section (second phase)
- application: structures
device: Aerospace fasteners and furnace components (distributor claim)
example: A distributor's listing for Ta97.5/W2.5 rod names aerospace fasteners, furnace components and electrical connector pins among its applications.
source: goodfellow-ta-w-rod
where: Product description
supply:
- subject: Tantalum
abundance: 'USGS: identified world tantalum resources are ''considered adequate to supply projected needs'', most of them in Australia, Brazil, Canada and China.'
producers:
- country: Congo (Kinshasa)
share_percent: 52
year: 2025
- country: Rwanda
share_percent: 16
year: 2025
- country: Nigeria
share_percent: 15.6
year: 2025
- country: Brazil
share_percent: 7.6
year: 2025
- country: China
share_percent: 3.2
year: 2025
- country: Australia
share_percent: 2
year: 2025
critical_lists: []
recycling: 'USGS: tantalum was recycled mostly from new scrap, and the amount recycled was not available; recycling ''may account for as much as 30%'' of consumption by domestic primary processors.'
substitutes:
- 'USGS: hafnium, iridium, molybdenum, niobium, rhenium, and tungsten can substitute for tantalum in high-temperature applications, with performance loss or higher costs.'
source: usgs-mcs2026-tantalum
where: World Mine Production and Reserves table, 2025e column (tantalum content, metric tons; world total 2,500; shares calculated by Space Mushroom against that total); Recycling; Substitutes
- subject: Tungsten (alloying element)
abundance: Not given in the USGS tungsten summary we read.
producers:
- country: China
share_percent: 78.8
year: 2025
- country: Vietnam
share_percent: 3.5
year: 2025
- country: Kazakhstan
share_percent: 2.8
year: 2025
- country: Russia
share_percent: 2.4
year: 2025
- country: Korea North
share_percent: 2.4
year: 2025
critical_lists: []
recycling: 'USGS: the estimated quantity of secondary tungsten produced in 2025 was withheld to avoid disclosing company proprietary data.'
substitutes:
- 'USGS: molybdenum can substitute for certain tungsten mill products, and depleted uranium or lead can substitute for tungsten or tungsten alloys where high density or radiation shielding is required.'
source: usgs-mcs2026-tungsten
where: World Mine Production and Reserves table, 2025 column (tungsten content, metric tons; world total 85,000; shares calculated by Space Mushroom against that total); Recycling; Substitutes
documents:
- title: ATI Ta10W Technical Data Sheet (tantalum-10% tungsten), 2013
type: datasheet
url: https://www.atimaterials.com/Products/Documents/datasheets/niobium-hafnium-tantalum-vanadium/tantalum/ati_Ta10W_v5.pdf
year: 2013
- title: 'ASTM B708 tantalum and tantalum alloy plate, sheet and strip: supplier summary with UNS R05252 and R05255 tables'
type: standard
url: https://gsalloy.com/?p=837
- title: 'Goodfellow: Tantalum-Tungsten Rod (Ta97.5-W2.5), product page'
type: datasheet
url: https://www.goodfellow.com/usa/tantalum-tungsten-alloy-rod-ta97-5-w2-5-group
- title: 'USGS Mineral Commodity Summaries 2026: Tantalum'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
year: 2026
- title: 'USGS Mineral Commodity Summaries 2026: Tungsten'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
year: 2026
- title: 'NASA NTRS 19660009067: Preliminary Results of a Study of Coated Ta-10W Sheet for Heat-Shield Applications (1966)'
type: report
url: https://ntrs.nasa.gov/citations/19660009067
year: 1966
- title: 'PubChem compound record: Tantalum (CID 23956), GHS classification and safety summary'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/23956
- title: 'Wikipedia: Tantalum–tungsten alloys (names and composition)'
type: database
url: https://en.wikipedia.org/wiki/Tantalum%E2%80%93tungsten_alloys
year: 2026
gaps:
- No ASTM B708 standard text was opened; the specification minimums come from one supplier summary of that standard (gsalloy page).
- No manufacturer datasheet for Ta-2.5W was found. Its property values come from one distributor listing (a 2.5 mm rod, as drawn) and from the ASTM B708 minimums, so they are not a grade-wide datasheet.
- Wikipedia's mechanical-properties table for both grades (credited there to the ASM Handbook, 1990) gives strength and hardness values that differ from the ATI and ASTM figures here. Those values are not recorded, because this brief limits Wikipedia to composition and history, and the ASM Handbook was not opened.
- Coefficient of thermal expansion in ppm/K for Ta-10W was not found; the ATI table gives thermal strain only. The Goodfellow Ta-2.5W coefficient is printed with an exponent (x10 to the minus 6 per kelvin), so it was left out.
- Thermal conductivity for Ta-10W is printed by ATI in cal/(cm2)(sec)(K/cm) and is kept in that unit; no W/(m·K) value was read for Ta-10W.
- Electrical resistivity, Poisson's ratio and modulus for Ta-10W were not found in the sources read.
- No uncoated oxidation rate for Ta-10W or Ta-2.5W in air was found; the only oxidation lives are for coated coupons.
- No flight, space-radiation, atomic-oxygen, outgassing (ASTM E595) or cryogenic result was found for either grade. The 1966 NASA heat-shield work was ground testing.
- The NASA 1966 report text was read from an OCR-type PDF; only the legible rows of Table I are recorded, and the 2000 °F row is the one used.
- PubChem's hazard summary is for tantalum metal (CID 23956), not for the tungsten-containing alloy. No SDS for a Ta-W alloy was read.
- No EN, DIN or JIS designation for either grade was printed in a source read in this run.
- 'Critical-minerals status for tantalum and tungsten was not confirmed: the USGS 2026 summaries read here do not mention a critical-minerals list, and the USGS 2025 list and EU list were not opened.'
- Tungsten's own abundance (crustal) figure was not looked up.
- The Ta-10W residual limits (carbon, nitrogen, hydrogen) are in the ATI table but were not recorded as properties; only oxygen was kept.
sources:
ati-ta10w:
title: ATI Ta10W Technical Data Sheet (tantalum-10% tungsten), Allegheny Technologies, 8 pages, dated 5/13/13
id: ATI Ta10W v5; trade name ATI Ta10W
url: https://www.atimaterials.com/Products/Documents/datasheets/niobium-hafnium-tantalum-vanadium/tantalum/ati_Ta10W_v5.pdf
year: 2013
kind: datasheet
license: Manufacturer datasheet, typical data (cited, not reproduced)
gsalloy-astm-b708:
title: ASTM B708 Tantalum and Tantalum Alloy Plate, Sheet, and Strip (supplier summary with UNS R05252 and R05255 tables, Golden Sunbird Metals)
id: ASTM B708; UNS R05252; UNS R05255; Tantaloy 60; Tantaloy 63
url: https://gsalloy.com/?p=837
kind: web
license: Supplier web page (cited, not reproduced)
goodfellow-ta-w-rod:
title: Tantalum-Tungsten Rod (Ta97.5-W2.5), Goodfellow product page
id: Goodfellow Ta97.5/W2.5 rod, 2.5 mm, as drawn
url: https://www.goodfellow.com/usa/tantalum-tungsten-alloy-rod-ta97-5-w2-5-group
kind: web
license: Distributor web page (cited, not reproduced)
usgs-mcs2026-tantalum:
title: Mineral Commodity Summaries 2026, Tantalum
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
year: 2026
kind: report
license: public domain (USGS)
usgs-mcs2026-tungsten:
title: Mineral Commodity Summaries 2026, Tungsten
id: USGS MCS 2026, February 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
year: 2026
kind: report
license: public domain (USGS)
nasa-1966-ta10w:
title: Preliminary Results of a Study of Coated Ta-10W Sheet for Heat-Shield Applications (Wichorek and Stein, NASA Langley Research Center)
id: NTRS 19660009067
url: https://ntrs.nasa.gov/citations/19660009067
year: 1966
kind: report
license: public domain (NASA)
pubchem-ta:
title: 'PubChem compound record: Tantalum (CID 23956), GHS classification and safety summary'
id: CID 23956; CAS 7440-25-7
url: https://pubchem.ncbi.nlm.nih.gov/compound/23956
year: 2026
kind: database
license: public domain (NCBI)
wikipedia-taw:
title: Tantalum–tungsten alloys (Wikipedia; composition, names and crystal structure only)
url: https://en.wikipedia.org/wiki/Tantalum%E2%80%93tungsten_alloys
year: 2026
kind: web
license: CC BY-SA 4.0 (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-11-01'
review:
status: draft
method: assistant
checked_values: 36
unreachable: 0
caveats: 5
note: 'Read by an AI assistant on 2026-11-01 from the ATI datasheet, the GS Alloy ASTM B708 summary, the Goodfellow page, the USGS 2026 tantalum and tungsten summaries, the NASA NTRS 1966 report (text read from its PDF) and the PubChem record. Caveats: ATI values are typical data; ASTM values are minimums from a supplier summary; the Ta-2.5W properties come from one distributor listing; the NASA values are coated-coupon ground tests; the ATI thermal conductivity is kept in its printed unit.'
story:
recipe:
line: Tantalum-tungsten alloys are tantalum metal with tungsten added in solid solution. Ta-10W (UNS R05255) holds 9.0 to 11.0 % tungsten by weight, and Ta-2.5W (UNS R05252) holds 2.0 to 3.5 %, with the rest tantalum. The GS Alloy summary of ASTM B708 lists electron-beam furnace or vacuum-arc melting as the routes for these grades.
parts:
- name: Tantalum
symbol: Ta
share_note: balance
role: The base metal. It is a refractory metal with a high melting point and good corrosion resistance (ATI).
- name: Tungsten
symbol: W
share_percent: 9
share_high: 11
source: gsalloy-astm-b708
where: Chemical Composition table, UNS R05255 column (Ta-10W); Ta-2.5W uses 2.0 to 3.5 %
role: Adds strength and high-temperature stability. Tungsten has the highest melting point of the elements, which the alloy inherits in part.
risk_groups:
- title: For people
lead: The sources we hold describe the hazards of tantalum metal in general, not of the alloy. Bulk metal is the lower-risk form; fine powder is the concern.
level: 1
verdict: 'Bulk metal: low hazard; powder can ignite'
points:
- label: Bulk form
line: PubChem says tantalum metal 'does not meet GHS hazard criteria for 44% (200 of 455) of reports', and it lists H228 and H252 only where codes were given.
- label: Powder
line: PubChem says metallic tantalum powder 'presents a fire...hazard' and that bulk tantalum is 'much less reactive' than the powder.
- title: If the coating fails
lead: These results come from laboratory oxidation tests on coated coupons, not from field or flight use.
level: 2
verdict: Coating life limits hot-air service
points:
- label: Coated coupon in air
line: In a 1966 NASA Langley test, a coated Ta-10W coupon failed after 45 hours of 1-hour cycles at 2000 °F, after losing 0.0009 inch of substrate.
- label: Silicon coating
line: In ATI's cyclic tests, a silicon coating on Ta-10W lasted 50 hours at 2200 °F.
- label: Strength when hot
line: Recrystallized Ta-10W sheet falls from 80,000 to 95,000 psi ultimate tensile strength at room temperature to 36,200 to 37,100 psi at 2600 °F (ATI nominal values).
- title: Handling and storage
points:
- label: Welding
line: ATI says welded Ta-10W has essentially the same properties as the base metal, and names electron-beam and inert-gas fusion welding.
- label: Specify the form
line: The ASTM B708 minimums apply to plate, sheet and strip. The ATI values are typical data for recrystallized sheet, and the Goodfellow values are for an as-drawn rod, so state the form and temper when you specify strength.
why: 'Tantalum-tungsten alloys keep their strength at high temperature and resist corrosion, which is why they are used for hot parts. Ta-10W is the stronger grade with 9.0 to 11.0 % tungsten (UNS R05255), and Ta-2.5W has 2.0 to 3.5 % (UNS R05252). ATI describes the alloy for elevated-temperature aerospace parts such as nozzles, inserts and structural material. Its main limit is oxidation in air: the sources we hold give coated lives in hours, and no life for bare metal.'
uses:
- where: Aerospace hot parts
line: ATI describes Ta-10W for elevated-temperature use in aerospace, including nozzles, inserts, directional devices and structural materials.
- where: Heat shields, tested on the ground
line: A 1966 NASA Langley study tested coated Ta-10W sheet for heat-shield use and built corrugated heat-shield panels from it. It was a ground study, not a flight.
- where: Fasteners and furnace parts
line: A distributor lists aerospace fasteners, furnace components and electrical connector pins as uses for its Ta-2.5W rod. That is a supplier claim, not a test result.
can_do:
- label: Melting
value: 3035 °C
benchmark: melting_point
line: ATI gives a melting point of 3035 °C for Ta-10W. A distributor gives 3014 °C for Ta-2.5W. The two figures are for different grades, so they should be read side by side, not ranked.
- label: Strength when cold
value: 481 MPa minimum
benchmark: ultimate_tensile_strength
line: ASTM B708 sets a minimum tensile strength of 481 MPa for Ta-10W plate, sheet and strip, and a minimum yield strength of 414 MPa. The minimum for Ta-2.5W is 276 MPa tensile and 193 MPa yield.
- label: Strength when hot
value: 36,200 to 37,100 psi at 2600 °F
benchmark: ultimate_tensile_strength
line: ATI gives 36,200 to 37,100 psi ultimate tensile strength at 2600 °F for recrystallized Ta-10W sheet, against 80,000 to 95,000 psi at room temperature.
- label: Coating life
value: 50 hours at 2200 °F
benchmark: coating_life_cyclic
line: In ATI's cyclic tests, a silicon coating on Ta-10W lasted 50 hours at 2200 °F. A 50Sn-50Al coating (weight percent) lasted 290 hours at the same temperature.
- label: Density
value: 16.9 g/cm3
benchmark: density
line: ATI gives a density of 16.9 g/cm3 for Ta-10W. A distributor gives 16.66 g/cm3 for Ta-2.5W.
compare: 'Ta-10W and Ta-2.5W are both heavy: ATI gives 16.9 g/cm3 for Ta-10W, and a distributor gives 16.66 g/cm3 for Ta-2.5W. The melting points printed are 3035 °C for Ta-10W (ATI) and 3014 °C for Ta-2.5W (distributor), two different sources and two different grades. Ta-10W has the higher minimum strength in ASTM B708, at 481 MPa tensile against 276 MPa for Ta-2.5W, and the lower minimum elongation, at 15 % against 20 %. The table compares the two grades on density, melting point and tensile strength.'
compare_rows:
- label: Density
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Tensile strength (minimum)
benchmark: ultimate_tensile_strength
handling:
- Specify the grade and form. Ta-10W and Ta-2.5W differ in strength, and the ATI and ASTM figures are for different product forms.
- Weld by electron-beam or inert-gas fusion methods, as the ATI datasheet describes.
- Keep bulk metal and fine powder apart. Powder is the form PubChem flags as flammable and self-heating.
good_for:
- 'Hot structural and nozzle parts: ATI names nozzles, inserts and structural material for elevated-temperature aerospace use.'
- 'Corrosion resistance: ATI says the alloy has excellent corrosion resistance in many media, with no rate given.'
watch_out:
- 'Oxidation in air: the lives in the sources are for coated coupons, 45 hours at 2000 °F in one NASA test.'
- 'Density: 16.9 g/cm3 for Ta-10W, so it is heavy compared with the structural metals in this collection.'
- 'Strength depends on form and temper: the ATI figures are typical values for recrystallized sheet, and the ASTM figures are minimums.'
- No space-environment result for either grade was found in the sources read; the 1966 NASA work was a ground test.
verdict: Tantalum-tungsten alloys are strong, corrosion-resistant metals for hot parts. Ta-10W is the stronger grade, at 481 MPa minimum tensile strength, and is heavy at 16.9 g/cm3. In air they need a coating, and the sources we hold give coated lives only, not a life for bare metal.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| ATI Ta10W Technical Data Sheet (tantalum-10% tungsten), Allegheny Technologies, 8 pages, dated 5/13/13 | datasheet | 2013 | 23 values | |
| ASTM B708 Tantalum and Tantalum Alloy Plate, Sheet, and Strip (supplier summary with UNS R05252 and R05255 tables, Golden Sunbird Metals) | web | 9 values | ||
| Tantalum-Tungsten Rod (Ta97.5-W2.5), Goodfellow product page | web | 8 values | ||
| Mineral Commodity Summaries 2026, Tantalum | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026, Tungsten | report | 2026 | 1 value | |
| Preliminary Results of a Study of Coated Ta-10W Sheet for Heat-Shield Applications (Wichorek and Stein, NASA Langley Research Center) | report | 1966 | 7 values | |
| PubChem compound record: Tantalum (CID 23956), GHS classification and safety summary | database | 2026 | 5 values | |
| Tantalum–tungsten alloys (Wikipedia; composition, names and crystal structure only) | web | 2026 | 1 value |
Updated