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.