{ "spore": "profile", "id": "vanadium-niobium", "spore_version": "0.2", "family": "refractory-metals", "name": "Vanadium alloys (V-4Cr-4Ti, V-Ti, V-Nb)", "abbreviation": "V alloys", "role": "fusion first-wall and blanket structural alloys, and vanadium-based hydrogen-permeation membranes", "category": "metals", "type": "refractory-metals", "summary": "The reference vanadium alloy for fusion is V-4Cr-4Ti, a vanadium base with about 4 percent chromium and 4 percent titanium by weight. Argonne reports high ductility, with about 20 percent uniform elongation. A property compilation gives a room-temperature yield strength of about 402 MPa, calculated here from its published correlation. After neutron irradiation to 28 to 46 dpa at 400 to 600 C, uniform elongation stayed above 8 percent. In air and oxygen at 500 to 700 C the alloy forms a surface oxide, and in Pint and DiStefano's tests the oxide did not prevent embrittlement. Vanadium-titanium-nickel and vanadium-niobium-titanium alloys are being studied as hydrogen-permeation membranes. A Savannah River test found a V-Ti-Ni membrane with a higher hydrogen permeation rate than palladium at 22 C, but the sources read here give no tensile data for the binary V-Ti or V-Nb alloys.\n", "best_for": "Fusion first-wall and blanket structures that must carry load at high temperature with low activation (Argonne)", "weakest_at": "Oxygen and hydrogen pickup: the alloy embrittles after exposure to oxygen at 500 to 700 C, and vanadium-based membranes are highly susceptible to hydrogen embrittlement", "identity": { "formula": "V-4Cr-4Ti: vanadium with nominal 4 wt.% Cr and 4 wt.% Ti (Argonne Table 1 heats: BL-47 4.1Cr-4.3Ti, 832665 3.8Cr-3.9Ti, T87 4.9Cr-5.1Ti, BL-63 4.6Cr-5.1Ti, in wt.%; trace nitrogen 28 to 220 wppm). V-Ti-Ni membrane tested by SRS: 53 wt.% V, 26 wt.% Ti, 21 wt.% Ni. V-Nb-Ti-Co: quaternary, composition not stated in the page used.", "designations": [], "source": "unt-smith-1996", "where": "Section 2 and Table 1, Compositions of Vanadium Base Alloys (nominal composition, wt.%)" }, "tags": { "environments": [], "stresses": [], "applications": [ "structures", "propulsion-and-tanks" ] }, "properties": [ { "benchmark": "density", "label": "Density, V-4Cr-4Ti at room temperature", "value": 6.05, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "room temperature (RT), as printed", "unit_in_source": "6.05x10 3 kg/m3 (the page's unit; entered as 6.05 g/cm3, the same value)" }, "method": "Value printed in the RT Density row of a property compilation for V-4Cr-4Ti (courtesy of Mike Billone), citing the ITER Materials Properties Handbook. Printed as 6.05x10 3 kg/m3; entered in g/cm3 with the same number", "status": "ground", "source": "qedfusion-v4cr4ti", "where": "Property table, RT Density row", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, V-4Cr-4Ti", "value": 1900, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "tolerance": "plus or minus 25 C as printed" }, "method": "Value printed in the property compilation for V-4Cr-4Ti, citing the ITER Materials Properties Handbook", "status": "ground", "source": "qedfusion-v4cr4ti", "where": "Property table, Melting temp. row", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "elastic_modulus", "label": "Young's modulus, V-4Cr-4Ti at 20 C", "value": 125.6, "bound": "exact", "unit": "GPa", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "20 C", "correlation": "printed as 125.6 times (1 minus 7.69 x 10-5 times (T minus 20)), valid RT to 1627 C" }, "method": "Calculated by Space Mushroom from the printed correlation at 20 C, where the temperature term is 1.00 and the value equals the prefactor", "status": "calculated", "source": "qedfusion-v4cr4ti", "where": "Property table, Young's modulus row", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "yield_strength", "label": "Yield strength, V-4Cr-4Ti at 20 C (from correlation)", "value": 402, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "20 C", "basis": "printed correlation Sy = 402 times a temperature polynomial that equals 1.00 at 20 C, valid RT to 700 C", "temper": "not stated in the compilation" }, "method": "Calculated by Space Mushroom from the printed correlation evaluated at 20 C; the compilation says the correlation is fitted from several references", "status": "calculated", "source": "qedfusion-v4cr4ti", "where": "Property table, Yield Strength row (see also its Fig. 2)", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "design_yield_strength", "label": "Design yield strength, V-4Cr-4Ti at 20 C (from correlation)", "value": 322, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "20 C", "basis": "printed design correlation Syd = 322 times the same polynomial, equal to 1.00 at 20 C" }, "method": "Calculated by Space Mushroom from the printed design correlation evaluated at 20 C", "status": "calculated", "source": "qedfusion-v4cr4ti", "where": "Property table, Design Yield Strength row", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, V-4Cr-4Ti at 20 C (from correlation)", "value": 488, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "20 C", "basis": "printed correlation Su = 488 times a temperature polynomial that equals 1.00 at 20 C, valid RT to 700 C" }, "method": "Calculated by Space Mushroom from the printed correlation evaluated at 20 C", "status": "calculated", "source": "qedfusion-v4cr4ti", "where": "Property table, Ultimate Tensile Strength row (see also its Fig. 1)", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "design_ultimate_tensile_strength", "label": "Design ultimate tensile strength, V-4Cr-4Ti at 20 C (from correlation)", "value": 424, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "20 C", "basis": "printed design correlation Sud = 424 times the same polynomial, equal to 1.00 at 20 C" }, "method": "Calculated by Space Mushroom from the printed design correlation evaluated at 20 C", "status": "calculated", "source": "qedfusion-v4cr4ti", "where": "Property table, Ultimate Design Tensile Strength row", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "elongation", "label": "Total elongation, V-4Cr-4Ti at 20 C (from correlation)", "value": 30.8, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "temperature": "20 C", "basis": "printed correlation et = 30.8 times a temperature polynomial that equals 1.00 at 20 C" }, "method": "Calculated by Space Mushroom from the printed correlation evaluated at 20 C", "status": "calculated", "source": "qedfusion-v4cr4ti", "where": "Property table, Total elongation row (see also its Fig. 4)", "source_detail": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" } }, { "benchmark": "uniform_elongation", "label": "Uniform elongation, V-4Cr-4Ti, unirradiated", "value": 20, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti (BL-47 and production heat 832665), unirradiated", "temperature": "room temperature to 700 C", "basis": "about 20 percent, printed as -20 percent; the text calls this high ductility" }, "method": "Value stated in the tensile section of the Argonne reference-alloy paper", "status": "ground", "source": "unt-smith-1996", "where": "Section 4, Tensile Properties", "source_detail": { "title": "Reference vanadium alloy V-4Cr-4Ti for fusion application (Smith, Chung, Loomis and Tsai, Argonne National Laboratory, received 1996)", "id": "Argonne National Laboratory, UNT digital library record metadc667725", "url": "https://digital.library.unt.edu/ark:/67531/metadc667725/m2/1/high_res_d/195723.pdf", "year": 1996, "kind": "paper", "license": "US Government report (publicly available)" } }, { "benchmark": "uniform_elongation", "label": "Uniform elongation, V-4Cr-4Ti after neutron irradiation", "value": 8, "bound": "lower", "unit": "%", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti", "irradiation": "28 to 46 dpa at 400 to 600 C in fast reactors", "test": "at the irradiation temperature and at room temperature after irradiation at 420 to 600 C" }, "method": "Value stated in the irradiation section of the Argonne reference-alloy paper; the paper says greater than 8 percent", "status": "ground", "source": "unt-smith-1996", "where": "Section 6, Irradiation Effects, text on Fig. 10", "source_detail": { "title": "Reference vanadium alloy V-4Cr-4Ti for fusion application (Smith, Chung, Loomis and Tsai, Argonne National Laboratory, received 1996)", "id": "Argonne National Laboratory, UNT digital library record metadc667725", "url": "https://digital.library.unt.edu/ark:/67531/metadc667725/m2/1/high_res_d/195723.pdf", "year": 1996, "kind": "paper", "license": "US Government report (publicly available)" } }, { "benchmark": "reduction_in_area", "label": "Reduction in area, V-4Cr-4Ti at 600 C and below", "value": 70, "bound": "lower", "unit": "%", "scope": "material", "conditions": { "grade": "V-4Cr-4Ti and V-5Cr-5Ti heats in the paper", "temperature": "600 C and below", "basis": "greater than 70 percent as printed" }, "method": "Value stated in the tensile section of the Argonne reference-alloy paper", "status": "ground", "source": "unt-smith-1996", "where": "Section 4, Tensile Properties, text on Fig. 7", "source_detail": { "title": "Reference vanadium alloy V-4Cr-4Ti for fusion application (Smith, Chung, Loomis and Tsai, Argonne National Laboratory, received 1996)", "id": "Argonne National Laboratory, UNT digital library record metadc667725", "url": "https://digital.library.unt.edu/ark:/67531/metadc667725/m2/1/high_res_d/195723.pdf", "year": 1996, "kind": "paper", "license": "US Government report (publicly available)" } }, { "benchmark": "ductile_brittle_transition_temperature", "label": "Ductile-to-brittle transition temperature, Charpy, unirradiated", "value": -200, "bound": "upper", "unit": "°C", "scope": "material", "conditions": { "grade": "two V-4Cr-4Ti heats (BL-47 and production heat 832665) and one V-5Cr-5Ti heat (T87)", "treatment": "thermal-mechanical treatments including 1 h anneals at 950 to 1125 C", "method": "Charpy one-third-size specimens" }, "method": "Value stated in the impact section; the paper says the DBTT is below -200 C for all three heats", "status": "ground", "source": "unt-smith-1996", "where": "Section 3, Impact Properties, and Figure 1", "source_detail": { "title": "Reference vanadium alloy V-4Cr-4Ti for fusion application (Smith, Chung, Loomis and Tsai, Argonne National Laboratory, received 1996)", "id": "Argonne National Laboratory, UNT digital library record metadc667725", "url": "https://digital.library.unt.edu/ark:/67531/metadc667725/m2/1/high_res_d/195723.pdf", "year": 1996, "kind": "paper", "license": "US Government report (publicly available)" } } ], "corrosion": [ { "environment": "Air and oxygen at 500 to 700 C, uncoated V-4Cr-4Ti", "headline": "In air and oxygen at 500 to 700 C, V-4Cr-4Ti forms a surface oxide and then embrittles, even when the oxide is present.", "effect": "Pint and DiStefano exposed V-4Cr-4Ti to air, oxygen and low-pressure oxygen at 500 to 700 C. Linear oxidation kinetics were measured up to 2000 hr at low oxygen pressure. At higher pressures, oxygen uptake and an external oxide layer followed linear-parabolic kinetics. Tensile ductility at 25 and 600 C was reduced. Specimens with an external oxide were embrittled severely after a further 2000 hr anneal at 700 C, and the authors conclude that a surface oxide will not prevent degradation.", "rating": "severe", "conditions": { "exposure": "500 to 700 C, air or oxygen at 105 Pa and low oxygen pressure, up to 2000 hr", "alloy": "V-4Cr-4Ti", "tests": "tensile tests at 25 and 600 C after exposure" }, "source": "pint-distefano-2005", "where": "Abstract" }, { "environment": "Liquid lithium, as a coolant or breeder in fusion blankets", "headline": "The reference-alloy paper calls V-4Cr-4Ti compatible with lithium.", "effect": "The Argonne paper lists good compatibility with lithium among the reasons vanadium-base alloys are candidates for fusion first-wall and blanket structures. It gives no corrosion rate, exposure time or temperature for that statement, so treat it as a qualitative finding.", "rating": "low", "conditions": { "basis": "general statement in the introduction of the reference-alloy paper, with no test conditions given", "alloy": "V-4Cr-4Ti and related V-Cr-Ti alloys" }, "source": "unt-smith-1996", "where": "Section 1, Introduction" } ], "risks": { "hazards": [ { "text": "Vanadium powder, sold by Stanford Advanced Materials, is classified as a flammable solid (H228), causes skin and eye irritation (H315, H319) and may cause respiratory irritation (H335). Its signal word is Danger. The classification applies to the powder, not to a bulk alloy part.", "ghs": [ "H228", "H315", "H319", "H335" ], "source": "sds-vanadium-powder", "where": "Section 2, Hazards Identification (GHS labelling)" }, { "text": "PubChem records that vanadium does not meet GHS hazard criteria in 95.4 percent (431 of 452) of company reports, and that 21 of 452 reports give hazard codes. The codes are not printed in the record extract read here.", "ghs": [], "source": "pubchem-vanadium", "where": "GHS Classification section, aggregated ECHA C and L notifications" } ], "failure_risks": [ { "mode": "Oxygen embrittlement of V-4Cr-4Ti in air or oxygen", "trigger": "Exposure to air or oxygen at 500 to 700 C, followed in the test by a further anneal at 700 C", "consequence": "Pint and DiStefano measured reduced tensile ductility after exposure, and severe embrittlement after a 2000 hr anneal at 700 C of specimens that had formed an external oxide.", "severity": "high", "source": "pint-distefano-2005", "where": "Abstract" }, { "mode": "Hydrogen embrittlement of a vanadium-based membrane alloy", "trigger": "Hydrogen absorbed into a vanadium-based alloy, for example during hydrogen permeation", "consequence": "The Qingdao paper says larger hydrogen absorption weakens mechanical strength. Substituting niobium for vanadium in V-Nb-Ti-Co alloys shifted the ductile-to-brittle transition hydrogen concentration about 0.36 H/M to the right.", "severity": "high", "source": "qust-vnbti-co", "where": "Abstract" } ], "side_effects": [], "handling": [ { "text": "Keep the powder in a cool, dry place in tightly closed containers, with adequate ventilation, and away from oxidizing agents. Do not use water on a fire: the SDS calls for a special powder for metal fires.", "source": "sds-vanadium-powder", "where": "Sections 5 and 7 (storage, extinguishing media)" } ], "mitigations": [ { "text": "The Argonne paper reports little effect of anneal temperature on impact properties when V-4Cr-4Ti is annealed in a high-vacuum system.", "source": "unt-smith-1996", "where": "Section 3, Impact Properties" } ] }, "uses": [ { "application": "structures", "device": "Fusion reactor first-wall and blanket structures", "example": "Argonne describes vanadium-base alloys as promising candidates for fusion reactor first-wall and blanket structures because of low irradiation-induced activity, good mechanical properties, good compatibility with lithium and high thermal conductivity.", "source": "unt-smith-1996", "where": "Section 1, Introduction" }, { "application": "propulsion-and-tanks", "device": "Hydrogen separation membrane (purifier for hydrogen feed gas)", "example": "Savannah River tested an arc-melted V53-Ti26-Ni21 membrane, which had a steady-state hydrogen permeation rate an order of magnitude higher than pure palladium at 22 C. The report describes applications such as front-end purifiers for fuel-cell systems. This is the closest allowed application value for a hydrogen separation membrane; it is a laboratory result, not a flight use.", "source": "srs-vtin", "where": "Abstract, Results and Discussion, Table 1" } ], "supply": [ { "subject": "Vanadium (mine production, 2025 estimate)", "producers": [ { "country": "China", "share_percent": 74.5, "year": 2025 }, { "country": "Russia", "share_percent": 19.1, "year": 2025 }, { "country": "Brazil", "share_percent": 4.8, "year": 2025 }, { "country": "South Africa", "share_percent": 4.5, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 List of Critical Minerals (vanadium included)", "listed": true }, { "list": "EU critical raw materials list (vanadium included)", "listed": true } ], "recycling": "USGS: recycling of vanadium is mainly reprocessing of vanadium catalysts into new catalysts.", "substitutes": [ "USGS: manganese, molybdenum, niobium, titanium and tungsten are to some degree interchangeable with vanadium in steel. No acceptable substitute for vanadium is available for use in aerospace titanium alloys." ], "source": "usgs-mcs2026-vanadium", "where": "World Mine Production and Reserves table, 2025e (China 82,000 t, Russia 21,000 t, Brazil 5,300 t, South Africa 5,000 t; world total 110,000 thousand t, rounded). Shares calculated by Space Mushroom against that total; Recycling and Substitutes paragraphs." } ], "media": [], "documents": [ { "title": "USGS Mineral Commodity Summaries 2026: Vanadium", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-vanadium.pdf", "year": 2026 }, { "title": "Safety data sheet, spherical vanadium powder (CAS 7440-62-2), Stanford Advanced Materials", "type": "sds", "url": "https://samaterials.com/tds/1697121437-spherical-vanadium-powder-sds.pdf", "year": 2023 }, { "title": "PubChem compound record: Vanadium (CID 23990), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23990/JSON?heading=GHS+Classification", "year": 2026 }, { "title": "NIST Atomic Weights and Isotopic Compositions: vanadium", "type": "database", "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=V&all=all&ascii=html", "year": 2026 }, { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "type": "datasheet", "url": "https://qedfusion.org/LIB/PROPS/vprop.html" }, { "title": "Reference vanadium alloy V-4Cr-4Ti for fusion application, Smith, Chung, Loomis and Tsai, Argonne National Laboratory", "type": "paper", "url": "https://digital.library.unt.edu/ark:/67531/metadc667725/m2/1/high_res_d/195723.pdf", "year": 1996 }, { "title": "Hydrogen Permeability of Multiphase V-Ti-Ni Metallic Membranes, Adams and Mickalonis, Savannah River National Laboratory", "type": "report", "url": "https://sti.srs.gov/fulltext/2005/ms2005619.pdf", "year": 2005 }, { "title": "The role of oxygen uptake and scale formation on the embrittlement of vanadium alloys, Pint and DiStefano, Oxidation of Metals 63, 33-55", "type": "paper", "url": "https://doi.org/10.1007/s11085-005-1950-7", "year": 2005 } ], "gaps": [ "No numeric density, melting point or tensile data for binary V-Nb or V-Ti alloys were found in the sources read. The only V-Nb sources read are a quaternary V-Nb-Ti-Co hydrogen paper (qualitative) and a 1984 Metallurgical Transactions A hydrogen study that was not opened.", "V-Cr-Ti: only V-4Cr-4Ti (and V-5Cr-5Ti heats for the impact row) were read in full. The property compilation gives thermal conductivity, specific heat and expansion for V-5Cr-5Ti only, so those rows were left out.", "Hydrogen permeation rates from the Savannah River table (Pd 3.3-4.3 x 10-10 and V53-Ti26-Ni21 1.0-3.7 x 10-9 mol H2/(m s)) were not entered: the exponent form and the mol H2/(m s) unit were not checked against the site unit registry. The order-of-magnitude comparison is stated in the story instead.", "Irradiated yield strength above 800 MPa at about 390 C was seen only in a search snippet and not in an opened page, so it is not entered.", "Atomic weights for titanium, chromium and niobium were not checked against NIST. Only vanadium (50.9415) was read, so the recipe gives shares for Cr and Ti.", "The V-4Cr-4Ti design values (design yield and design ultimate strength), reduction in area and ductile-to-brittle transition temperature use non-canonical snake_case names. Uniform elongation is also snake_case. The canon has no entries for these.", "Composition basis: the Argonne Table 1 heading reads wt.%, but the summary text writes V-4Cr-4Ti without units. The nominal composition is taken from Table 1.", "No UNS, ASTM or AMS designation for V-4Cr-4Ti, V-Ti or V-Nb was found in the sources used, so designations are empty.", "Titanium and niobium production shares were not found (USGS titanium and niobium summaries not opened). Critical-list status for titanium metal and niobium came from the USGS and EU list pages only.", "Vanadium crustal abundance was not found in the sources used.", "No space-environment data (outgassing, atomic oxygen, radiation, thermal-vacuum) were found in the sources read.", "PubChem hazard codes beyond the 'not classified' counts were not in the extract. The SDS covers the powder only; no hazard statement was found for bulk V-4Cr-4Ti.", "The oxygen embrittlement threshold (0.2 percent oxygen) from a 2022 review was found in a search snippet only, so it is not used." ], "story": { "why": "Vanadium alloys are candidates for fusion-reactor first walls and blankets, where a structural metal must survive high temperatures, neutron damage and contact with lithium. The reference alloy, V-4Cr-4Ti, keeps about 20 percent uniform elongation unirradiated, and still keeps more than 8 percent after irradiation to 28 to 46 dpa at 400 to 600 C. It is also being studied as a hydrogen-permeation membrane. The same vanadium that gives these properties takes up oxygen and hydrogen, so the chemistry must be controlled.", "uses": [ { "where": "Fusion first wall and blanket", "line": "Argonne calls vanadium-base alloys promising for fusion reactor first-wall and blanket structures, citing low activation, good mechanical properties, compatibility with lithium and high thermal conductivity." }, { "where": "Hydrogen separation membranes", "line": "Savannah River measured a V-Ti-Ni membrane with a hydrogen permeation rate an order of magnitude higher than palladium at 22 C, in a laboratory electrochemical test. The alloy is a candidate substitute for costly palladium membranes." } ], "can_do": [ { "label": "Strength when unirradiated", "line": "The printed correlation for V-4Cr-4Ti gives a yield strength of 402 MPa and an ultimate tensile strength of 488 MPa at 20 C (calculated from the published fit).", "benchmark": "yield_strength", "scope": "material", "value": "402 MPa yield at 20 C" }, { "label": "Ductility", "line": "Argonne reports high ductility, about 20 percent uniform elongation, for the alloys tested from room temperature to 700 C. The reduction in area is greater than 70 percent at 600 C and below.", "scope": "material", "value": "20 percent uniform elongation" }, { "label": "Low-temperature toughness", "line": "Charpy tests found the ductile-to-brittle transition temperature below -200 C for the two V-4Cr-4Ti heats and one V-5Cr-5Ti heat.", "benchmark": "ductile_brittle_transition_temperature", "scope": "material", "value": "DBTT below -200 C" }, { "label": "Density", "line": "V-4Cr-4Ti has a room-temperature density of 6.05 g/cm3.", "benchmark": "density", "scope": "material", "value": "6.05 g/cm3" } ], "compare": "V-4Cr-4Ti has a room-temperature density of 6.05 g/cm3, a melting point of about 1900 C and a Young's modulus of about 125.6 GPa at 20 C. Its unirradiated room-temperature yield strength is about 402 MPa, calculated from the printed correlation rather than read from a test table. The vanadium-based membrane alloy trades structural strength for hydrogen permeability, and its hydrogen absorption is the main weakness.", "compare_rows": [ { "label": "Density", "benchmark": "density", "scope": "material" }, { "label": "Melting point", "benchmark": "melting_point", "scope": "material" }, { "label": "Young's modulus", "benchmark": "elastic_modulus", "scope": "material" } ], "handling": [ "Keep the powder in a cool, dry place in closed containers, away from oxidizing agents, with adequate ventilation (SDS).", "Do not use water on a vanadium powder fire; use a special powder for metal fires (SDS).", "Protect hot components from oxygen: the alloy forms a surface oxide at 500 to 700 C that does not stop embrittlement (Pint and DiStefano)." ], "good_for": [ "High-temperature structure with low activation for fusion first walls, where Argonne reports good ductility after irradiation (more than 8 percent uniform elongation).", "Hydrogen-permeation membranes as a palladium substitute: the V-Ti-Ni alloy permeated hydrogen about ten times faster than palladium in the SRS test." ], "watch_out": [ "Oxygen embrittlement: at 500 to 700 C in air or oxygen, the surface oxide does not prevent embrittlement.", "Hydrogen embrittlement: high hydrogen absorption weakens vanadium-based membranes.", "No tensile data for the binary V-Ti or V-Nb alloys were found, so the quoted strengths apply only to V-4Cr-4Ti." ], "verdict": "V-4Cr-4Ti is the reference vanadium structural alloy for fusion first walls and blankets, with good ductility and lithium compatibility. Vanadium-based membranes are promising for hydrogen separation, but they embrittle with hydrogen and oxygen, and the sources read give no binary V-Nb or V-Ti property data.", "recipe": { "line": "V-4Cr-4Ti is vanadium with about 4 wt.% chromium and 4 wt.% titanium. Argonne's Table 1 gives 4.1Cr-4.3Ti for the 30 kg laboratory heat BL-47, 3.8Cr-3.9Ti for the 500 kg production heat 832665, and 4.9Cr-5.1Ti and 4.6Cr-5.1Ti for two V-5Cr-5Ti heats. Trace impurities in the heats listed were 310 to 440 wppm oxygen and 28 to 220 wppm nitrogen. The Savannah River V-Ti-Ni membrane alloy is 53 wt.% V, 26 wt.% Ti and 21 wt.% Ni, arc melted in argon.", "parts": [ { "name": "Vanadium", "symbol": "V", "role": "The base metal. Argonne cites its inherently low irradiation-induced activity as one reason vanadium-base alloys are candidates for fusion structures.", "share_note": "balance of the alloy" }, { "name": "Chromium", "symbol": "Cr", "role": "Alloying addition in the V-Cr-Ti family. Argonne selected V-4Cr-4Ti as the reference composition after screening V-Ti, V-Cr-Ti and V-Ti-Si alloys.", "share_note": "about 4 wt.% nominal (3.8 to 4.9 wt.% in the heats listed in Argonne Table 1)" }, { "name": "Titanium", "symbol": "Ti", "role": "Alloying addition in the V-Cr-Ti family. In the Savannah River membrane alloy (V-Ti-Ni) titanium is a major constituent, at 26 wt.%.", "share_note": "about 4 wt.% nominal (3.9 to 5.1 wt.% in the heats listed in Argonne Table 1)" } ] }, "risk_groups": [ { "title": "For people", "lead": "The powder is a flammable solid in the supplier safety data sheet. Bulk alloy parts have no hazard statement in the sources read.", "points": [ { "label": "Vanadium powder", "line": "The Stanford Advanced Materials safety data sheet classifies vanadium powder as Flammable solid (H228), with H315, H319 and H335 for skin, eye and respiratory irritation. The signal word is Danger." }, { "label": "Bulk alloy", "line": "No hazard statement was found in the sources read for bulk V-4Cr-4Ti. PubChem records that vanadium does not meet GHS hazard criteria in 95.4 percent of its reports." }, { "label": "In a fire", "line": "The SDS says to use a special powder for metal fires and not water." } ], "level": 1, "verdict": "Flammable as powder, no bulk hazard read" }, { "title": "If it fails", "lead": "The failure routes are oxygen embrittlement in hot air and hydrogen embrittlement in membranes.", "points": [ { "label": "Hot air", "line": "At 500 to 700 C, V-4Cr-4Ti forms a surface oxide. Pint and DiStefano found that the oxide did not prevent embrittlement, and specimens were severely embrittled after a 2000 hr anneal at 700 C." }, { "label": "Hydrogen", "line": "The Qingdao study of V-Nb-Ti-Co alloys says that high hydrogen absorption weakens vanadium-based alloys, and that replacing vanadium with niobium shifted the transition hydrogen concentration about 0.36 H/M." } ], "verdict": "Oxygen and hydrogen both embrittle the alloy" } ] }, "updated": "2026-10-26", "review": { "status": "draft", "method": "assistant", "checked_values": 12, "unreachable": 0, "caveats": 4, "note": "Values read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Caveats: the V-4Cr-4Ti strength values are from a printed correlation, evaluated at 20 C, not from a test table; no binary V-Nb or V-Ti property data were found; the hydrogen permeation table is not entered; the list statuses come from a summarising fetch of the USGS and EU pages." }, "sources": { "usgs-mcs2026-vanadium": { "title": "Mineral Commodity Summaries 2026, Vanadium, February 2026", "id": "USGS MCS 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-vanadium.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-crit2025": { "title": "About the 2025 List of Critical Minerals (USGS, final list)", "id": "Final 2025 List of Critical Minerals", "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals", "year": 2025, "kind": "web", "license": "public domain (USGS)" }, "ec-crm": { "title": "Critical raw materials (European Commission, list under Regulation (EU) 2024/1252)", "id": "Regulation (EU) 2024/1252", "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en", "year": 2024, "kind": "web", "license": "European Commission web page" }, "pubchem-vanadium": { "title": "PubChem compound record: Vanadium (CID 23990), GHS Classification section", "id": "CID 23990; ECHA C and L aggregated notifications", "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23990/JSON?heading=GHS+Classification", "kind": "database", "license": "PubChem (NCBI), public domain" }, "nist-vanadium": { "title": "NIST Atomic Weights and Isotopic Compositions for All Elements: vanadium", "id": "NIST, standard atomic weight of V", "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=V&all=all&ascii=html", "kind": "database", "license": "NIST public data" }, "sds-vanadium-powder": { "title": "Safety data sheet, spherical vanadium powder, Stanford Advanced Materials", "id": "CAS 7440-62-2; revised 02/02/2023", "url": "https://samaterials.com/tds/1697121437-spherical-vanadium-powder-sds.pdf", "kind": "datasheet", "license": "supplier safety data sheet (cited, not reproduced)" }, "qedfusion-v4cr4ti": { "title": "Properties of V-4Cr-4Ti (property compilation, courtesy of Mike Billone)", "id": "Cites ITER Materials Properties Handbook, Davis (1996), and ANL and ORNL reports", "url": "https://qedfusion.org/LIB/PROPS/vprop.html", "kind": "web", "license": "cited, not reproduced" }, "unt-smith-1996": { "title": "Reference vanadium alloy V-4Cr-4Ti for fusion application (Smith, Chung, Loomis and Tsai, Argonne National Laboratory, received 1996)", "id": "Argonne National Laboratory, UNT digital library record metadc667725", "url": "https://digital.library.unt.edu/ark:/67531/metadc667725/m2/1/high_res_d/195723.pdf", "year": 1996, "kind": "paper", "license": "US Government report (publicly available)" }, "srs-vtin": { "title": "Hydrogen Permeability of Multiphase V-Ti-Ni Metallic Membranes (Adams and Mickalonis, Savannah River National Laboratory)", "id": "SRS report MS2005619", "url": "https://sti.srs.gov/fulltext/2005/ms2005619.pdf", "year": 2005, "kind": "report", "license": "US Government report (publicly available)" }, "pint-distefano-2005": { "title": "The role of oxygen uptake and scale formation on the embrittlement of vanadium alloys (Oxidation of Metals 63, 33-55)", "id": "doi:10.1007/s11085-005-1950-7", "url": "https://doi.org/10.1007/s11085-005-1950-7", "year": 2005, "kind": "paper", "license": "publisher page (cited, not reproduced)" }, "qust-vnbti-co": { "title": "Microstructure, hydrogen permeability and ductile-to-brittle transition-hydrogen concentration of (V, Nb)-Ti-Co quaternary alloys (Qingdao University of Science and Technology, author page)", "id": "Journal volume 305 (journal not named on the author page)", "url": "https://faculty.qust.edu.cn/zhaoping12/en/lwcg/144406/content/310556.htm", "kind": "web", "license": "author page (cited, not reproduced)" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/vanadium-niobium/" }