Molybdenum-tungsten alloy (Mo-30W) Mo-30W
Mo-30W: molybdenum base with about 30 wt % tungsten (28 to 32 % in Polema, 27 to 33 wt % in ASTM B386 Alloy 366, nominal 30 % in Climelt)
Also known as ASTM 366, CLIMELT Mo-30W, MoW30-PM
Mo-30W is a molybdenum alloy with about 30 % tungsten (Climelt, Polema, ASTM B386 Alloy 366).
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 point
2829 °C
Weight
10.9 g/cm3 minimum
Strength when hot
170 MPa at 1600 °C
Strength after recrystallisation
385 MPa at 1500 °C
Recipe, share of the weight
- Mo balance (about 70 %)Molybdenum
- W 28 to 32%Tungsten
Best for
Refractory parts that must hold shape at high temperature in vacuum or inert furnaces, where the 2829 °C melting point and the 10.9 g/cm3 sintered minimum density are the reference figures
Weakest at
Strength falls off above about 1500 °C in the powder-metallurgy bar tested by Wang et al., and the zinc-bath factory test found aluminium in the bath attacks the alloy
Risk at a glance
- People Low. Mixed notifications
- If it fails High. Aluminium attack on a heater casing in zinc
- Corrosion Low. Claimed chemically inert in molten zinc, with no rate given.
Quick facts: Mo-30W
| Property | Value | Basis |
|---|---|---|
| Density | 10.9 to 11.2 g/cm³ | 2 sourced values across conditions |
| Tensile strength | 170 to 385 MPa | 2 sourced values across conditions |
| Melting point | 2,829 °C | 1 sourced value |
What is the density of Molybdenum-tungsten alloy (Mo-30W)?
Molybdenum-tungsten alloy (Mo-30W) has a density of 10.9 to 11.2 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 melting point of Molybdenum-tungsten alloy (Mo-30W)?
Molybdenum-tungsten alloy (Mo-30W) has a melting point of 2,829 °C. The source and test conditions are listed in the properties table on this page.
What is the tensile strength of Molybdenum-tungsten alloy (Mo-30W)?
Molybdenum-tungsten alloy (Mo-30W) has a tensile strength of 170 to 385 MPa. 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 are the other names and codes for Molybdenum-tungsten alloy (Mo-30W)?
Molybdenum-tungsten alloy (Mo-30W) is also written as ASTM 366, CLIMELT Mo-30W, MoW30-PM. Each code is printed in the source listed beside it in the designations table.
What is Molybdenum-tungsten alloy (Mo-30W) used for?
Uses recorded in the sources include Sputtering target for thin-film coatings; Hot-zone parts of vacuum and hydrogen furnaces; Crucible for melting corundum to grow sapphire monocrystals.
Why it exists
Mo-30W is a molybdenum alloy with about 30 % tungsten. It is used where the part must keep its shape at high temperature, in vacuum or hydrogen furnaces, for sapphire crucibles and for thin-film sputtering targets. Burman (1984) gives a melting point of 2829 °C, and Polema gives minimum crucible densities of 10.9 g/cm3 (sintered) and 11.2 g/cm3 (forged). The zinc-bath use depends on bath temperature and aluminium content.
Where it's used
Sputtering targets
Polema lists MoW alloy sputtering targets for thin-film electronic components and functional coatings.
Furnace hot zones
Polema lists heat zones of vacuum and hydrogen furnaces, for smelting quartz glass and growing sapphire crystals.
Zinc-bath heater casings
A factory test of Mo-30W inner heating casings in molten zinc was reported in a Chinese-language article (abstract read).
Recipe
Mo-30W: molybdenum base with about 30 wt % tungsten (28 to 32 % in Polema, 27 to 33 wt % in ASTM B386 Alloy 366, nominal 30 % in Climelt)
Mo-30W is a molybdenum-base alloy with about 30 % tungsten. Polema gives 28 to 32 % tungsten for its crucibles, ASTM B386 Alloy 366 is 27 to 33 wt %, and Climelt is nominal 70 % Mo to 30 % W. Polema makes it as sintered or forged shapes, and the Wang et al. bar was made by powder metallurgy. ASTM B386 Alloy 366 is vacuum arc-cast.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Molybdenum Mo | balance (about 70 %) | The matrix of the alloy, with a body-centred cubic structure. |
| Tungsten W | 28 to 32% | Forms a solid solution with molybdenum, which Polema credits for the alloy's creep resistance and machinability. |
Weight shares are as printed in the sources.
What it can do
Melting point
2829 °C
measured
Burman (1984) gives 2829 °C, cited for its high melting temperature and its inertness in molten zinc.
Weight
10.9 g/cm3 minimum
measured
Polema gives at least 10.9 g/cm3 for sintered MoW30-PM crucibles.
Strength when hot
170 MPa at 1600 °C
measured
The Wang et al. bar has a tensile strength of 170 MPa and 10 % elongation at 1600 °C.
Strength after recrystallisation
385 MPa at 1500 °C
measured
The fully recrystallised bar has a tensile strength of 385 MPa and HV10 185 at 1500 °C, the lowest values in the study.
How it compares
Polema says Mo-30W has temperature resistance and creep resistance higher than molybdenum, and higher machinability than tungsten. No numeric comparison with pure molybdenum was read in this run, so the compare rows show Mo-30W values only.
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. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | Mo-30W | W | WC | Hf | Mo | Mo-Re | TZM | Nb | Nb alloys | Re | W-Re | WHA | W-Cu | W-Ag | WT20 | V | V alloys | Zr | Zr alloys | TiH2 | Be |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | |||||||||||||||||||||
| Melting point of Mo-30W | 2829 °C1 | 3695 K | no data | 2233 °C | 2623 °C | > 2610 °C | no data | 2477 °C | 2350 °C | 3186 °C | 3350 °C | no data | no data | no data | 3695 K | 1910 °C | 1900 °C | 1852 °C | 1850 °C | > 400 °C | 1287 °C |
| Physical and electrical | |||||||||||||||||||||
| Minimum density of sintered MoW30-PM crucibles | 10.9 g/cm³2 | 19250 kg/m3 | 14.8 g/cm³ | 13.3 g/cm³ | 10.22 g/cm³ | 14.6 g/cm³ | 10.2 g/cm³ | 8.582 g/cm³ | 8.85 g/cm³ | 21.02 g/cm³ | 19.4 g/cm³ | 16.85 to 17.25 g/cc | 15.15 g/cm³ | 11.75 to 16.1 g/cm³ | 19250 kg m-3 | 6.11 g/cm³ | 6.05 g/cm³ | 6.51 g/cm³ | 6.55 g/cc | 3.91 g/cm³ | 1.85 g/cm³ |
| Minimum density of forged MoW30-PM crucibles | 11.2 g/cm³3 | 19250 kg/m3 | 14.8 g/cm³ | 13.3 g/cm³ | 10.22 g/cm³ | 14.6 g/cm³ | 10.2 g/cm³ | 8.582 g/cm³ | 8.85 g/cm³ | 21.02 g/cm³ | 19.4 g/cm³ | 16.85 to 17.25 g/cc | 15.15 g/cm³ | 11.75 to 16.1 g/cm³ | 19250 kg m-3 | 6.11 g/cm³ | 6.05 g/cm³ | 6.51 g/cm³ | 6.55 g/cc | 3.91 g/cm³ | 1.85 g/cm³ |
| Vickers hardness of fully recrystallised Mo-30W at 1500 °C | 185 HV107 | no data | no data | no data | no data | no data | 200 to 250 HV | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data |
| Other measurements | |||||||||||||||||||||
| Tensile strength of Mo-30W bar at 1600 °C | 170 MPa4 | no data | no data | > 400 MPa | 411 MPa | 719 MPa | 800 to 1000 MPa | 386 MPa | 386 MPa | 400 to 700 MPa | 220 x 10^3 psi | 758 MPa | 620 to 689 MPa | no data | no data | no data | 488 MPa | 468.1 MPa | 541 MPa | no data | > 290 MPa |
| Elongation of Mo-30W bar at 1600 °C | 10 %5 | no data | no data | > 20 % | no data | 18 % | 6 to 10 % | 20 % | 20 % | 30 to 50 % | 20 % | 5 % | 8.3 % | no data | no data | 35 % | 30.8 % | 28.9 % | 28 % | no data | > 3 % |
| Tensile strength of fully recrystallised Mo-30W at 1500 °C | 385 MPa6 | no data | no data | > 400 MPa | 411 MPa | 719 MPa | 800 to 1000 MPa | 386 MPa | 386 MPa | 400 to 700 MPa | 220 x 10^3 psi | 758 MPa | 620 to 689 MPa | no data | no data | no data | 488 MPa | 468.1 MPa | 541 MPa | no data | > 290 MPa |
Why choose it, and why not
Good for
- High-temperature furnace and hot-zone parts in vacuum or hydrogen: melting point 2829 °C (Burman, 1984).
- Sapphire crucibles and thin-film sputtering targets: Polema lists both uses.
- Heat resistance with better creep resistance and machinability than tungsten (Polema).
Watch out for
- Strength falls significantly above the 1300 to 1500 °C range in the Wang et al. bar.
- Aluminium in a galvanizing bath is named as the main cause of corrosion of Mo-30W heater casings.
- The zinc-bath claim of chemical inertness (Burman 1984, Climelt) conflicts with the factory-test finding, and no corrosion rate is printed.
- Thermal conductivity, electrical resistivity, expansion and modulus for Mo-30W were not found in a readable source.
Mo-30W is a molybdenum alloy with about 30 % tungsten, used for furnace hot zones, sapphire crucibles and sputtering targets. Burman (1984) gives a melting point of 2829 °C, Polema gives minimum crucible densities of 10.9 and 11.2 g/cm3, and the Wang et al. bar holds 385 MPa at 1500 °C after recrystallisation. For zinc baths the sources disagree, and the factory test names aluminium in the zinc as the main cause of corrosion. The thermal and electrical data that a designer would need are not in any source read here, so they should be obtained from the manufacturer before a design is fixed.
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 |
|---|---|
| ASTM | 366 |
| Trade name | CLIMELT Mo-30W, MoW30-PM (Polema grade, sintered and forged crucibles and rod) |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Melting point of Mo-30W | Value printed in the summary text of the 1984 ASTM symposium paper; no test method printed | composition Mo-30W, 30 % tungsten | — |
| 2 | Minimum density of sintered MoW30-PM crucibles | Manufacturer minimum specification for crucible density | form sintered MoW30-PM cruciblespec guaranteed minimum | — |
| 3 | Minimum density of forged MoW30-PM crucibles | Manufacturer minimum specification for crucible density | form forged MoW30-PM cruciblespec guaranteed minimum | — |
| 4 | Tensile strength of Mo-30W bar at 1600 °C | Tensile test as reported in the Wang et al. abstract | temperature 1600 °Cform bar made by powder metallurgystate tested as reported in the abstract | — |
| 5 | Elongation of Mo-30W bar at 1600 °C | Tensile test as reported in the Wang et al. abstract | temperature 1600 °Cform bar made by powder metallurgy | — |
| 6 | Tensile strength of fully recrystallised Mo-30W at 1500 °C | Tensile test as reported in the Wang et al. abstract; lowest strength in the study | temperature 1500 °Cstate completely recrystallised bar | — |
| 7 | Vickers hardness of fully recrystallised Mo-30W at 1500 °C | Vickers hardness as reported in the Wang et al. abstract; lowest hardness in the study | temperature 1500 °Cstate completely recrystallised bar | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Molten zinc in a hot-dip galvanizing bath (heater casing) | not rated | Corrosion speeds up with bath temperature, and aluminium in the zinc is the main cause.1 |
| Molten zinc, high-purity Mo-30W grades | low | Claimed chemically inert in molten zinc, with no rate given.2 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Molten zinc in a hot-dip galvanizing bath (heater casing) | The factory test of Mo-30W inner heating casings in molten zinc found that bath temperature is an important factor and that higher temperature speeds corrosion. The abstract says aluminium in the molten zinc reacts with Mo-30W and is the main reason for corrosion. Heater life also depends on impurities in the bath, heater design, heating power and alloy quality. The abstract prints no corrosion rate. | bath hot-dip galvanizing, three working conditions (not quantified in the abstract) |
| 2 | Molten zinc, high-purity Mo-30W grades | Burman (1984) says Mo-30W is commercially used for its melting point of 2829 °C and its chemical inertness in corrosive molten zinc, especially the high-purity grades. The Climelt datasheet abstract says the alloy is recommended for resistance to molten zinc. Neither source gives a corrosion rate, and this claim is at odds with the aluminium-attack finding above. | basis claim in a 1984 paper and a datasheet abstract; no test conditions printed |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
The hazard notifications are for the pure elements, not the alloy.
- Molybdenum as a substance
- PubChem notifications for molybdenum give H228 flammable solid for 30 % of reports and H361 for 29.5 %, but 57.4 % of 1523 reports meet no GHS criteria.
- Tungsten as a substance
- PubChem notifications for tungsten give H228 flammable solid for 73.4 % of reports, with H252, H320 and H335 also listed.
If it fails
The failure route in the sources is high temperature and aluminium in the zinc.
- High temperature
- Strength and hardness stay stable between 1300 and 1500 °C in the Wang et al. bar and then drop significantly, with 385 MPa and HV10 185 at 1500 °C after full recrystallisation.
- Aluminium in zinc
- The Mo-30W heater casing factory test calls aluminium in the molten zinc the main reason for corrosion.
Handling and storage
- Shock
- Polema says the products should not be subjected to shocks during use.
- Specify the form
- Sintered and forged crucibles have different minimum densities (10.9 and 11.2 g/cm3), so state the form when you order.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Loss of strength at high temperaturemoderate severity | Testing or service above the 1300 to 1500 °C range in the powder-metallurgy barStrength and hardness stay stable between 1300 and 1500 °C and then drop significantly. The fully recrystallised bar was lowest, at 385 MPa and HV10 185 at 1500 °C. |
| Aluminium attack on a heater casing in zinchigh severity | Aluminium in a hot-dip galvanizing bath at higher bath temperatureHeater life is shortened. The factory test calls aluminium in the zinc the main reason for corrosion. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Zinc bath maintenance | The zinc-bath heater casing is a surface that wears by corrosion, so its life sets how often the heater is replaced. The sources do not give a replacement rate. |
Handling and storage
- During use, the products should not be subjected to shocks.
- Specify the form, because the minimum density differs between sintered (10.9 g/cm3) and forged (11.2 g/cm3) crucibles.
Mitigations
- Heater life depends on bath temperature, impurities in the bath, heater design, heating power and alloy quality, and the factory test lists these as the factors to control.
Supply and geography
How common the raw materials are and where they come from.
Molybdenum
World mine production 260,000 t in 2025 (estimated), 256,000 t in 2024. World reserves 17,000 thousand t. Identified resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world.
- Top producers (2025)
- China, Chile, United States, Peru, Mexico
- Recycling
- Molybdenum recycled in new and old steel and other scrap may be as much as 30 % of the apparent supply of molybdenum (USGS). There is no separate recovery process for secondary molybdenum from its alloys.
- Substitutes
- There is little substitution for molybdenum in its major application in steels and cast irons (USGS).
Tungsten
World mine production 85,000 t in 2025 (estimated), 82,000 t in 2024. China 67,000 t in both years, with reserves of 2,500,000 t. World reserves more than 4,700,000 t.
- Top producers (2025)
- China, Russia, Vietnam
- Recycling
- Not read in this run.
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.
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spore: profile
id: molybdenum-tungsten
spore_version: 0.2
family: refractory-metals
name: Molybdenum-tungsten alloy (Mo-30W)
abbreviation: Mo-30W
role: high-temperature molybdenum-tungsten alloy for furnace hot zones, crucibles, zinc-bath heaters and sputtering targets
category: metals
type: refractory-metals
summary: |
Mo-30W is a molybdenum alloy with about 30 % tungsten (Climelt, Polema, ASTM B386 Alloy 366). Polema sells it as sintered and forged crucibles with minimum densities of 10.9 and 11.2 g/cm3, and it also lists the alloy for vacuum and hydrogen furnace parts and for sputtering targets. Burman (1984) gives a melting point of 2829 °C. A powder-metallurgy bar of the alloy had a tensile strength of 170 MPa at 1600 °C and 385 MPa at 1500 °C after full recrystallisation. In molten zinc, a factory test of heater casings ties corrosion to bath temperature and to aluminium in the zinc, although an older datasheet calls the alloy chemically inert in molten zinc. Thermal conductivity, electrical resistivity, expansion and modulus were not found in any readable source.
best_for: Refractory parts that must hold shape at high temperature in vacuum or inert furnaces, where the 2829 °C melting point and the 10.9 g/cm3 sintered minimum density are the reference figures
weakest_at: Strength falls off above about 1500 °C in the powder-metallurgy bar tested by Wang et al., and the zinc-bath factory test found aluminium in the bath attacks the alloy
identity:
formula: 'Mo-30W: molybdenum base with about 30 wt % tungsten (28 to 32 % in Polema, 27 to 33 wt % in ASTM B386 Alloy 366, nominal 30 % in Climelt)'
source: polema
where: 'Section 3, Chemical composition of crucibles: molybdenum is the base, with 28-32% tungsten'
designations:
- system: ASTM
code: '366'
note: Molybdenum Alloy 366, vacuum arc-cast Mo-30W, plate, sheet and strip under ASTM B386
source: gsalloy-b386
where: 'Grade definitions: Molybdenum Alloy 366, vacuum arc-cast molybdenum-30 % tungsten alloy'
- system: Trade name
code: CLIMELT Mo-30W
source: climelt-mo30w
where: Page title of the Alloy Digest entry, Mo-9
- system: Trade name
code: MoW30-PM
note: Polema grade, sintered and forged crucibles and rod
source: polema
where: Section 3, crucibles, and Section 4, products for high-temperature furnaces
tags:
environments: []
stresses:
- extreme-heat
applications:
- electronics-and-chips
- thermal-control
properties:
- benchmark: melting_point
label: Melting point of Mo-30W
value: 2829
unit: °C
scope: material
conditions:
composition: Mo-30W, 30 % tungsten
method: Value printed in the summary text of the 1984 ASTM symposium paper; no test method printed
status: ground
source: burman1984
where: Summary text on the ASTM store page (paper visible in summary; full text paywalled)
- benchmark: density
label: Minimum density of sintered MoW30-PM crucibles
value: 10.9
unit: g/cm3
scope: material
conditions:
form: sintered MoW30-PM crucible
spec: guaranteed minimum
method: Manufacturer minimum specification for crucible density
status: ground
source: polema
where: 'Section 3, Crucible density: sintered MoW30-PM crucibles, at least 10.9 g/cm3'
- benchmark: density
label: Minimum density of forged MoW30-PM crucibles
value: 11.2
unit: g/cm3
scope: material
conditions:
form: forged MoW30-PM crucible
spec: guaranteed minimum
method: Manufacturer minimum specification for crucible density
status: ground
source: polema
where: 'Section 3, Crucible density: forged MoW30-PM crucibles, at least 11.2 g/cm3'
- benchmark: ultimate_tensile_strength
label: Tensile strength of Mo-30W bar at 1600 °C
value: 170
unit: MPa
scope: material
conditions:
temperature: 1600 °C
form: bar made by powder metallurgy
state: tested as reported in the abstract
method: Tensile test as reported in the Wang et al. abstract
status: ground
source: wang2018
where: Abstract, sentence beginning 'the tensile strength of Mo-30 W molybdenum alloy bar at 1600'
- benchmark: elongation
label: Elongation of Mo-30W bar at 1600 °C
value: 10
unit: '%'
scope: material
conditions:
temperature: 1600 °C
form: bar made by powder metallurgy
method: Tensile test as reported in the Wang et al. abstract
status: ground
source: wang2018
where: Abstract, same sentence as the 170 MPa value
- benchmark: ultimate_tensile_strength
label: Tensile strength of fully recrystallised Mo-30W at 1500 °C
value: 385
unit: MPa
scope: material
conditions:
temperature: 1500 °C
state: completely recrystallised bar
method: Tensile test as reported in the Wang et al. abstract; lowest strength in the study
status: ground
source: wang2018
where: Abstract, sentence beginning 'The Mo-30 W molybdenum alloy are completely recrystallized at 1500'
- benchmark: hardness_vickers
label: Vickers hardness of fully recrystallised Mo-30W at 1500 °C
value: 185
unit: HV10
scope: material
conditions:
temperature: 1500 °C
state: completely recrystallised bar
method: Vickers hardness as reported in the Wang et al. abstract; lowest hardness in the study
status: ground
source: wang2018
where: Abstract, HV10 185 at 1500 °C (hardness_vickers is not in property-canon.yaml; see gaps)
corrosion:
- environment: Molten zinc in a hot-dip galvanizing bath (heater casing)
headline: Corrosion speeds up with bath temperature, and aluminium in the zinc is the main cause.
effect: The factory test of Mo-30W inner heating casings in molten zinc found that bath temperature is an important factor and that higher temperature speeds corrosion. The abstract says aluminium in the molten zinc reacts with Mo-30W and is the main reason for corrosion. Heater life also depends on impurities in the bath, heater design, heating power and alloy quality. The abstract prints no corrosion rate.
rating: unknown
conditions:
bath: hot-dip galvanizing, three working conditions (not quantified in the abstract)
source: mattest
where: Abstract of the Chinese-language article, title 热镀锌用Mo-30W合金内加热套管的腐蚀性能
- environment: Molten zinc, high-purity Mo-30W grades
headline: Claimed chemically inert in molten zinc, with no rate given.
effect: Burman (1984) says Mo-30W is commercially used for its melting point of 2829 °C and its chemical inertness in corrosive molten zinc, especially the high-purity grades. The Climelt datasheet abstract says the alloy is recommended for resistance to molten zinc. Neither source gives a corrosion rate, and this claim is at odds with the aluminium-attack finding above.
rating: low
conditions:
basis: claim in a 1984 paper and a datasheet abstract; no test conditions printed
source: burman1984
where: Summary text on the ASTM store page
risks:
hazards:
- text: 'PubChem GHS aggregated notifications for the element molybdenum: H228 flammable solid (30 % of reports), H361 suspected of damaging fertility or the unborn child (29.5 %), H315 causes skin irritation and H319 causes serious eye irritation. PubChem also says 57.4 % of 1523 reports meet no GHS criteria.'
ghs:
- H228
- H361
- H315
- H319
source: pubchem-mo
where: GHS Classification, aggregated notifications (CID 23932)
- text: 'PubChem GHS aggregated notifications for the element tungsten: H228 flammable solid (73.4 % of reports), H252 self-heating in large quantities, H320 eye irritation and H335 respiratory irritation. These describe the element, not the alloy, and the record does not give the physical form.'
ghs:
- H228
- H252
- H320
- H335
source: pubchem-w
where: GHS Classification, aggregated notifications (CID 23964)
failure_risks:
- mode: Loss of strength at high temperature
trigger: Testing or service above the 1300 to 1500 °C range in the powder-metallurgy bar
consequence: Strength and hardness stay stable between 1300 and 1500 °C and then drop significantly. The fully recrystallised bar was lowest, at 385 MPa and HV10 185 at 1500 °C.
severity: moderate
source: wang2018
where: Abstract
- mode: Aluminium attack on a heater casing in zinc
trigger: Aluminium in a hot-dip galvanizing bath at higher bath temperature
consequence: Heater life is shortened. The factory test calls aluminium in the zinc the main reason for corrosion.
severity: high
source: mattest
where: Abstract
side_effects:
- text: The zinc-bath heater casing is a surface that wears by corrosion, so its life sets how often the heater is replaced. The sources do not give a replacement rate.
affects: Zinc bath maintenance
source: mattest
where: Abstract
handling:
- text: During use, the products should not be subjected to shocks.
source: polema
- text: Specify the form, because the minimum density differs between sintered (10.9 g/cm3) and forged (11.2 g/cm3) crucibles.
source: polema
mitigations:
- text: Heater life depends on bath temperature, impurities in the bath, heater design, heating power and alloy quality, and the factory test lists these as the factors to control.
source: mattest
uses:
- application: electronics-and-chips
device: Sputtering target for thin-film coatings
example: Polema lists MoW alloy sputtering targets for thin films in electronic components and other functional coatings, and says MoW layers etch well in thin-film transistor work (matmatch, not opened).
source: polema
where: Section 5, Products from Molybdenum-tungsten alloy MoW10-PM for sputtering targets (the section title says MoW10-PM while the text says MoW30-PM (MoW10))
- application: thermal-control
device: Hot-zone parts of vacuum and hydrogen furnaces
example: Polema lists heat zones for smelting quartz glass, sapphire crystal growth and furnaces for annealing uranium fuel.
source: polema
where: Section 4, Products made from molybdenum, tungsten and their alloys for use in high-temperature furnaces
- application: thermal-control
device: Crucible for melting corundum to grow sapphire monocrystals
example: Sintered and forged MoW30 crucibles (TMB30-MP) used primarily to melt corundum for extremely pure sapphire.
source: polema
where: Section 3, Crucibles from molybdenum-tungsten alloy
- application: thermal-control
device: Inner heating casing (heater sleeve) in a hot-dip galvanizing zinc bath
example: A factory test of Mo-30W heater casings in molten zinc, reported in the Chinese-language article in the sources list.
source: mattest
where: Abstract. No application slug in the taxonomy fits a zinc-bath heater; the thermal-control slug is used as the nearest match.
supply:
- subject: Molybdenum
abundance: World mine production 260,000 t in 2025 (estimated), 256,000 t in 2024. World reserves 17,000 thousand t. Identified resources are about 5.4 million tons in the United States and about 20 million tons in the rest of the world.
producers:
- country: China
mine_production_t: 97000
year: 2025
- country: Chile
mine_production_t: 42000
year: 2025
- country: United States
mine_production_t: 40000
year: 2025
- country: Peru
mine_production_t: 39000
year: 2025
- country: Mexico
mine_production_t: 17000
year: 2025
critical_lists: []
recycling: Molybdenum recycled in new and old steel and other scrap may be as much as 30 % of the apparent supply of molybdenum (USGS). There is no separate recovery process for secondary molybdenum from its alloys.
substitutes:
- There is little substitution for molybdenum in its major application in steels and cast irons (USGS).
source: usgs-mo-2026
where: 'Molybdenum chapter: Events, Trends and Issues; World Mine Production and Reserves table; Recycling; Substitutes'
- subject: Tungsten
abundance: World mine production 85,000 t in 2025 (estimated), 82,000 t in 2024. China 67,000 t in both years, with reserves of 2,500,000 t. World reserves more than 4,700,000 t.
producers:
- country: China
mine_production_t: 67000
year: 2025
- country: Russia
mine_production_t: 2000
year: 2025
- country: Vietnam
mine_production_t: 3000
year: 2025
critical_lists: []
recycling: Not read in this run.
substitutes: []
source: usgs-w-2026
where: 'Tungsten chapter: World Mine Production and Reserves table; Events, Trends and Issues'
note: China implemented new export controls on selected tungsten items in February 2025 (USGS).
media: []
documents:
- title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.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: 'PubChem: Molybdenum (CID 23932), GHS classification summary'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/23932
year: 2026
- title: 'PubChem: Tungsten (CID 23964), GHS classification summary'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/23964
year: 2026
- title: Study on recrystallization behavior of Mo-30W molybdenum alloy (Powder Metallurgy Technology 2018)
type: paper
url: https://pmt.ustb.edu.cn/en/article/doi/10.19591/j.cnki.cn11-1974/tf.2018.06.003
year: 2018
- title: 'POLEMA: molybdenum-tungsten alloy products, crucibles and sputtering targets'
type: datasheet
url: https://polema.net/en/catalog/molibden/molibdenovye-splavy-mow-mola-i-drugie/
- title: CLIMELT Mo-30W High Temperature Alloy, Alloy Digest Mo-9 (abstract only, full datasheet paywalled)
type: datasheet
url: https://dl.asminternational.org/alloy-digest/article/19/4/Mo-9/1733/CLIMELT-Mo-30WHigh-Temperature-Alloy
year: 1970
gaps:
- 'Thermal conductivity of Mo-30W: no readable source found (Climelt datasheet paywalled, Plansee MoW30 datasheet not reachable, Wieland and matmatch not opened).'
- 'Electrical resistivity of Mo-30W: no value found in any readable source.'
- 'Coefficient of thermal expansion of Mo-30W: no value found in a readable source (a third-party comparison page printed one for a grade called 366, but it could not be re-opened in this run).'
- 'Elastic modulus of Mo-30W: no value found in a readable source.'
- 'Yield strength of Mo-30W: the Polema page gives only a conditional yield limit for MoW-2-PM, with no number. Not used, since its composition is not stated.'
- 'Hardness at temperatures other than 1500 °C: no value found; the Wang abstract gives stability between 1300 and 1500 °C but no numbers.'
- 'The Polema hot-rolled sheet (MoW-PM) and extruded stock (MoW-2-PM) tables are not used: neither page states the tungsten content, so the values may not belong to Mo-30W.'
- Polema's sputtering section is titled MoW10-PM but its text says MoW30-PM (MoW10). The product name is inconsistent and was not resolved.
- Hardness is named hardness_vickers because property-canon.yaml has no Vickers hardness name; the value is in units of HV10.
- No application slug in the taxonomy fits a zinc-bath heater; thermal-control is the nearest match.
- Corrosion rate in molten zinc is not printed in any readable source. The factory-test full text was not available, only the Chinese abstract.
- Burman (1984) calls the alloy chemically inert in molten zinc, but the Mo-30W factory test names aluminium in the zinc as the main cause of corrosion. The two claims conflict and were not resolved.
- No oxidation or high-temperature atmosphere data for Mo-30W were found in a readable source.
- Critical-mineral list status for molybdenum and tungsten is not stated in the USGS summaries read in this run. The EU and BGS lists were not checked.
- Tungsten recycling and substitutes were not in the USGS tungsten summary read in this run.
- PubChem hazard codes are aggregated notifications for the pure elements, not for the alloy. No Mo-30W safety data sheet was found.
- Publication year of the Polema page is not printed on the page.
- Year and author of the Chinese-language zinc-bath article were not visible in the fetched abstract.
- No openly licensed image was checked, so media is empty.
- The Plansee MoW30 datasheet, the matmatch MW30 page and the gsalloy product page were not reachable for full text (403 or DNS failure), so values from them are not used except the designation text from the gsalloy page.
sources:
usgs-mo-2026:
title: 'Mineral Commodity Summaries 2026: Molybdenum'
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
year: 2026
kind: report
license: public domain
usgs-w-2026:
title: 'Mineral Commodity Summaries 2026: Tungsten'
id: USGS MCS 2026
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
year: 2026
kind: report
license: public domain
polema:
title: 'POLEMA: molybdenum-tungsten alloy products (MoW-PM, MoW-2-PM, MoW30-PM crucibles, MoW10-PM sputtering targets)'
id: Polema catalogue page, molybdenum alloys
url: https://polema.net/en/catalog/molibden/molibdenovye-splavy-mow-mola-i-drugie/
kind: datasheet
license: supplier catalogue; facts cited
wang2018:
title: Study on recrystallization behavior of Mo-30W molybdenum alloy
id: DOI 10.19591/j.cnki.cn11-1974/tf.2018.06.003
url: https://pmt.ustb.edu.cn/en/article/doi/10.19591/j.cnki.cn11-1974/tf.2018.06.003
year: 2018
kind: paper
license: Powder Metallurgy Technology (journal abstract)
burman1984:
title: Symposium paper by R. Burman (AMAX Specialty Metals), ASTM STP 326, 1984 (full title not read)
id: DOI 10.1520/STP32629S (STP 326)
url: https://store.astm.org/stp32629s.html
year: 1984
kind: paper
license: ASTM (summary only)
climelt-mo30w:
title: CLIMELT Mo-30W High Temperature Alloy, Alloy Digest Mo-9 (Climax Molybdenum)
id: DOI 10.31399/asm.ad.mo0009
url: https://dl.asminternational.org/alloy-digest/article/19/4/Mo-9/1733/CLIMELT-Mo-30WHigh-Temperature-Alloy
year: 1970
kind: datasheet
license: ASM Alloy Digest (abstract only)
mattest:
title: 热镀锌用Mo-30W合金内加热套管的腐蚀性能 (Corrosion properties of Mo-30W alloy inner heating casing for hot-dip galvanizing)
id: Chinese-language article, mat-test.com record
url: https://fsyfh.mat-test.com/article/id/60433c86-e02c-4b74-bf52-93dddd198504
kind: paper
license: abstract read; full text not opened
gsalloy-b386:
title: ASTM B386 molybdenum and molybdenum alloy plate and sheet (supplier product page, Mo Alloy 366)
id: ASTM B386/B386M
url: https://gsalloy.com/product/astm-b386-molybdenum-and-molybdenum-alloy-plate-and-sheet/
kind: web
license: supplier page
pubchem-mo:
title: 'PubChem: Molybdenum (CID 23932), GHS classification'
id: CID 23932
url: https://pubchem.ncbi.nlm.nih.gov/compound/23932
kind: database
license: PubChem, public domain
pubchem-w:
title: 'PubChem: Tungsten (CID 23964), GHS classification'
id: CID 23964
url: https://pubchem.ncbi.nlm.nih.gov/compound/23964
kind: database
license: PubChem, public domain
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 7
unreachable: 4
caveats: 3
note: Written by an AI assistant on 2026-10-26. Seven property values were read in this run. Thermal conductivity, electrical resistivity, expansion and modulus were not found. The Plansee, matmatch, Climelt full-text and mat-test full-text pages were not reachable.
story:
recipe:
line: Mo-30W is a molybdenum-base alloy with about 30 % tungsten. Polema gives 28 to 32 % tungsten for its crucibles, ASTM B386 Alloy 366 is 27 to 33 wt %, and Climelt is nominal 70 % Mo to 30 % W. Polema makes it as sintered or forged shapes, and the Wang et al. bar was made by powder metallurgy. ASTM B386 Alloy 366 is vacuum arc-cast.
parts:
- name: Molybdenum
symbol: Mo
share_note: balance (about 70 %)
role: The matrix of the alloy, with a body-centred cubic structure.
- name: Tungsten
symbol: W
share_percent: 28
share_high: 32
role: Forms a solid solution with molybdenum, which Polema credits for the alloy's creep resistance and machinability.
risk_groups:
- title: For people
lead: The hazard notifications are for the pure elements, not the alloy.
level: 1
verdict: Mixed notifications
points:
- label: Molybdenum as a substance
line: PubChem notifications for molybdenum give H228 flammable solid for 30 % of reports and H361 for 29.5 %, but 57.4 % of 1523 reports meet no GHS criteria.
- label: Tungsten as a substance
line: PubChem notifications for tungsten give H228 flammable solid for 73.4 % of reports, with H252, H320 and H335 also listed.
- title: If it fails
lead: The failure route in the sources is high temperature and aluminium in the zinc.
points:
- label: High temperature
line: Strength and hardness stay stable between 1300 and 1500 °C in the Wang et al. bar and then drop significantly, with 385 MPa and HV10 185 at 1500 °C after full recrystallisation.
- label: Aluminium in zinc
line: The Mo-30W heater casing factory test calls aluminium in the molten zinc the main reason for corrosion.
- title: Handling and storage
points:
- label: Shock
line: Polema says the products should not be subjected to shocks during use.
- label: Specify the form
line: Sintered and forged crucibles have different minimum densities (10.9 and 11.2 g/cm3), so state the form when you order.
why: Mo-30W is a molybdenum alloy with about 30 % tungsten. It is used where the part must keep its shape at high temperature, in vacuum or hydrogen furnaces, for sapphire crucibles and for thin-film sputtering targets. Burman (1984) gives a melting point of 2829 °C, and Polema gives minimum crucible densities of 10.9 g/cm3 (sintered) and 11.2 g/cm3 (forged). The zinc-bath use depends on bath temperature and aluminium content.
uses:
- where: Sputtering targets
line: Polema lists MoW alloy sputtering targets for thin-film electronic components and functional coatings.
- where: Furnace hot zones
line: Polema lists heat zones of vacuum and hydrogen furnaces, for smelting quartz glass and growing sapphire crystals.
- where: Zinc-bath heater casings
line: A factory test of Mo-30W inner heating casings in molten zinc was reported in a Chinese-language article (abstract read).
can_do:
- label: Melting point
value: 2829 °C
benchmark: melting_point
line: Burman (1984) gives 2829 °C, cited for its high melting temperature and its inertness in molten zinc.
- label: Weight
value: 10.9 g/cm3 minimum
benchmark: density
line: Polema gives at least 10.9 g/cm3 for sintered MoW30-PM crucibles.
- label: Strength when hot
value: 170 MPa at 1600 °C
benchmark: ultimate_tensile_strength
line: The Wang et al. bar has a tensile strength of 170 MPa and 10 % elongation at 1600 °C.
- label: Strength after recrystallisation
value: 385 MPa at 1500 °C
benchmark: ultimate_tensile_strength
line: The fully recrystallised bar has a tensile strength of 385 MPa and HV10 185 at 1500 °C, the lowest values in the study.
compare: Polema says Mo-30W has temperature resistance and creep resistance higher than molybdenum, and higher machinability than tungsten. No numeric comparison with pure molybdenum was read in this run, so the compare rows show Mo-30W values only.
compare_rows:
- label: Density (crucible minimum)
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Tensile strength at 1500 °C
benchmark: ultimate_tensile_strength
handling:
- Do not subject the products to shocks during use (Polema).
- Specify sintered or forged form, because the minimum density differs (Polema).
- Test the zinc-bath heater casing against the bath temperature and aluminium content in the bath, since the factory test ties corrosion to both.
good_for:
- 'High-temperature furnace and hot-zone parts in vacuum or hydrogen: melting point 2829 °C (Burman, 1984).'
- 'Sapphire crucibles and thin-film sputtering targets: Polema lists both uses.'
- Heat resistance with better creep resistance and machinability than tungsten (Polema).
watch_out:
- Strength falls significantly above the 1300 to 1500 °C range in the Wang et al. bar.
- Aluminium in a galvanizing bath is named as the main cause of corrosion of Mo-30W heater casings.
- The zinc-bath claim of chemical inertness (Burman 1984, Climelt) conflicts with the factory-test finding, and no corrosion rate is printed.
- Thermal conductivity, electrical resistivity, expansion and modulus for Mo-30W were not found in a readable source.
verdict: Mo-30W is a molybdenum alloy with about 30 % tungsten, used for furnace hot zones, sapphire crucibles and sputtering targets. Burman (1984) gives a melting point of 2829 °C, Polema gives minimum crucible densities of 10.9 and 11.2 g/cm3, and the Wang et al. bar holds 385 MPa at 1500 °C after recrystallisation. For zinc baths the sources disagree, and the factory test names aluminium in the zinc as the main cause of corrosion. The thermal and electrical data that a designer would need are not in any source read here, so they should be obtained from the manufacturer before a design is fixed.
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 |
|---|---|---|---|---|
| Mineral Commodity Summaries 2026: Molybdenum | report | 2026 | 1 value | |
| Mineral Commodity Summaries 2026: Tungsten | report | 2026 | 1 value | |
| POLEMA: molybdenum-tungsten alloy products (MoW-PM, MoW-2-PM, MoW30-PM crucibles, MoW10-PM sputtering targets) | datasheet | 8 values | ||
| Study on recrystallization behavior of Mo-30W molybdenum alloy | paper | 2018 | 5 values | |
| Symposium paper by R. Burman (AMAX Specialty Metals), ASTM STP 326, 1984 (full title not read) | paper | 1984 | 2 values | |
| CLIMELT Mo-30W High Temperature Alloy, Alloy Digest Mo-9 (Climax Molybdenum) | datasheet | 1970 | 0 values | |
| 热镀锌用Mo-30W合金内加热套管的腐蚀性能 (Corrosion properties of Mo-30W alloy inner heating casing for hot-dip galvanizing) | paper | 5 values | ||
| ASTM B386 molybdenum and molybdenum alloy plate and sheet (supplier product page, Mo Alloy 366) | web | 0 values | ||
| PubChem: Molybdenum (CID 23932), GHS classification | database | 1 value | ||
| PubChem: Tungsten (CID 23964), GHS classification | database | 1 value |