{ "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.\n", "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", "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" } ], "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" }, "tags": { "environments": [], "stresses": [ "extreme-heat" ], "applications": [ "propulsion-and-tanks", "heat-shields", "structures" ] }, "properties": [ { "benchmark": "density", "label": "Density, Ta-10W (ATI Ta10W)", "value": 16.9, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "melting_point", "label": "Melting point, Ta-10W (ATI Ta10W)", "value": 3035, "bound": "exact", "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "benchmark": "ultimate_tensile_strength", "label": "Tensile strength at 2000 °F, stress-relieved sheet", "value": 60700, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "yield_strength", "label": "Yield strength at 2000 °F, stress-relieved sheet", "value": 55100, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "creep_rupture_time", "label": "Creep-rupture time, Ta-10W at 2000 °F under 52200 psi", "value": 1.5, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "thermal_strain", "label": "Thermal expansion strain, Ta-10W from room temperature to 5250 °F", "value": 0.0222, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, Ta-10W at 1700 K", "value": 0.135, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, Ta-10W at 3200 K", "value": 0.082, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "coating_life_cyclic", "label": "Cyclic coating life, silicon coating on Ta-10W at 2200 °F", "value": 50, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "coating_life_cyclic", "label": "Cyclic coating life, 50Sn-50Al coating on Ta-10W at 2200 °F", "value": 290, "bound": "exact", "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "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)", "source_detail": { "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)" } }, { "benchmark": "density", "label": "Density, Ta97.5/W2.5 (Ta-2.5W) rod", "value": 16.66, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "melting_point", "label": "Melting point, Ta97.5/W2.5 (Ta-2.5W) rod", "value": 3014, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "specific_heat", "label": "Specific heat, Ta97.5/W2.5 (Ta-2.5W) rod", "value": 141, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, Ta97.5/W2.5 (Ta-2.5W) rod", "value": 55, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "elastic_modulus", "label": "Modulus of elasticity, Ta97.5/W2.5 (Ta-2.5W) rod", "value": 186, "bound": "exact", "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "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", "source_detail": { "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)" } }, { "benchmark": "coating_life_cyclic", "label": "Cyclic oxidation life, coated Ta-10W coupon at 2000 °F", "value": 45, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "substrate_thickness_loss", "label": "Substrate thickness loss, coated Ta-10W coupon at 2000 °F", "value": 0.0009, "bound": "exact", "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", "source_detail": { "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)" } } ], "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" } ], "media": [], "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." ], "story": { "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", "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.", "benchmark": "melting_point", "scope": "material", "value": "3035 °C" }, { "label": "Strength when cold", "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.", "benchmark": "ultimate_tensile_strength", "scope": "material", "value": "481 MPa minimum" }, { "label": "Strength when hot", "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.", "benchmark": "ultimate_tensile_strength", "scope": "material", "value": "36,200 to 37,100 psi at 2600 °F" }, { "label": "Coating life", "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.", "benchmark": "coating_life_cyclic", "scope": "material", "value": "50 hours at 2200 °F" }, { "label": "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.", "benchmark": "density", "scope": "material", "value": "16.9 g/cm3" } ], "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", "scope": "material" }, { "label": "Melting point", "benchmark": "melting_point", "scope": "material" }, { "label": "Tensile strength (minimum)", "benchmark": "ultimate_tensile_strength", "scope": "material" } ], "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.", "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", "role": "The base metal. It is a refractory metal with a high melting point and good corrosion resistance (ATI).", "share_note": "balance" }, { "name": "Tungsten", "symbol": "W", "role": "Adds strength and high-temperature stability. Tungsten has the highest melting point of the elements, which the alloy inherits in part.", "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 %" } ] }, "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.", "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." } ], "level": 1, "verdict": "Bulk metal: low hazard; powder can ignite" }, { "title": "If the coating fails", "lead": "These results come from laboratory oxidation tests on coated coupons, not from field or flight use.", "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)." } ], "level": 2, "verdict": "Coating life limits hot-air service" }, { "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." } ] } ] }, "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." }, "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", "url": "https://spacemushroom.com/profiles/tantalum-tungsten-alloys/" }