{
  "spore": "profile",
  "id": "niobium",
  "spore_version": "0.2",
  "family": "refractory-metals",
  "name": "Niobium",
  "abbreviation": "Nb",
  "role": "refractory metal for high-temperature rocket nozzles, steel microalloying and superconducting wire",
  "category": "metals",
  "type": "refractory-metals",
  "summary": "Niobium (Nb, atomic number 41) is a body-centred cubic refractory metal with a melting point of 2477 °C and a density of 8.582 g/cm3 at 20 °C (Wikipedia infobox). Its alloy C-103 (Nb-10Hf-1Ti, UNS R04295) is used for liquid-rocket thruster nozzles. The Smiths High Performance datasheet gives minimum tensile yield strengths for recrystallised C-103 of 276 MPa at room temperature and 124 MPa at 1093 °C in vacuum. Niobium begins to oxidise in air at 200 °C, and the Golden Sunbird technical guide says C-103 needs a protective coating for extended service above 800 °C in oxidising air.\n",
  "best_for": "Hot structures that must hold stress above 1000 °C: C-103 keeps a minimum yield strength of 124 MPa at 1093 °C in vacuum (Smiths datasheet, minimum values)",
  "weakest_at": "Oxidation in air: niobium begins to oxidise at 200 °C, and unprotected C-103 needs a coating above 800 °C. C103 is expensive because of its hafnium content (NASA Glenn), and the USGS reports 100 % net import reliance for the United States.",
  "identity": {
    "formula": "Nb (element, atomic number 41); C-103 alloy Nb-10Hf-1Ti in wt% (ASTM B654 limits: Hf 9.0 to 11.0, Ti 0.7 to 1.3, Zr max 0.7, Ta max 0.5, W max 0.5)",
    "cas": "7440-03-1",
    "designations": [
      {
        "system": "UNS",
        "code": "R04295",
        "source": "stainless-c103",
        "where": "Header block, product title NIOBIUM C-103 with UNS R04295"
      },
      {
        "system": "Trade name",
        "code": "C-103",
        "source": "stainless-c103",
        "where": "Header block, NIOBIUM C-103 registered mark; Trademarks line reads Niobium C-103 alloy"
      },
      {
        "system": "ASTM",
        "code": "B654",
        "note": "plate, sheet and strip",
        "source": "stainless-c103",
        "where": "Header block, standards list: ASTM B652, B654, B655"
      },
      {
        "system": "ASTM",
        "code": "B655",
        "note": "bar and wire",
        "source": "smiths-c103",
        "where": "Related Specifications line: ASTM B652, B654, B655, AMS 7852, AMS 7857"
      },
      {
        "system": "AMS",
        "code": "7852",
        "note": "sheet, strip and plate",
        "source": "smiths-c103",
        "where": "Related Specifications line: AMS 7852"
      },
      {
        "system": "AMS",
        "code": "7857",
        "note": "bar, rod and wire",
        "source": "smiths-c103",
        "where": "Related Specifications line: AMS 7857"
      }
    ],
    "source": "uvm-niobium-sds",
    "where": "Section 3.1 Substances, row Niobium, CAS-No 7440-03-1, EC No. 231-113-5"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "propulsion-and-tanks",
      "structures",
      "in-space-manufacturing"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, pure niobium",
      "value": 8.582,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium",
        "temperature": "20 °C"
      },
      "method": "Value printed in the physical properties infobox of the Wikipedia article (cites a handbook)",
      "status": "ground",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Density (at 20° C) row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, C-103 alloy",
      "value": 8.86,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103 (Nb-10Hf-1Ti)",
        "temperature": "20 °C",
        "form": "wrought"
      },
      "method": "Value printed in a supplier datasheet, Physical properties at 20 °C",
      "status": "ground",
      "source": "stainless-c103",
      "where": "Physical properties at 20 °C, Density row",
      "source_detail": {
        "title": "Niobium C-103 (UNS R04295) technical datasheet, Stainless SA, Dannemarie-sur-Crete",
        "id": "UNS R04295; ASTM B652, B654, B655; AMS 7852, AMS 7857",
        "url": "https://www.stainless.eu/wp-content/uploads/2024/11/Niobium-C103%C2%AE-EN.pdf",
        "kind": "datasheet",
        "license": "manufacturer datasheet, general information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, pure niobium",
      "value": 2477,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium"
      },
      "method": "Value printed in the infobox of the Wikipedia article, given as 2750 K (2477 °C, 4491 °F)",
      "status": "ground",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Melting point row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, C-103 alloy",
      "value": 2350,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103 (Nb-10Hf-1Ti)",
        "tolerance": "plus or minus 50 °C as printed"
      },
      "method": "Value printed in a supplier datasheet, with a tolerance of plus or minus 50 °C",
      "status": "ground",
      "note": "The Smiths datasheet prints the same 2350 plus or minus 50 °C and the H.C. Starck datasheet prints 2350 °C.",
      "source": "stainless-c103",
      "where": "Physical properties at 20 °C, Melting point row",
      "source_detail": {
        "title": "Niobium C-103 (UNS R04295) technical datasheet, Stainless SA, Dannemarie-sur-Crete",
        "id": "UNS R04295; ASTM B652, B654, B655; AMS 7852, AMS 7857",
        "url": "https://www.stainless.eu/wp-content/uploads/2024/11/Niobium-C103%C2%AE-EN.pdf",
        "kind": "datasheet",
        "license": "manufacturer datasheet, general information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, pure niobium",
      "value": 4744,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium",
        "unit_in_source": "5017 K (4744 °C, 8571 °F)"
      },
      "method": "Value printed in the infobox of the Wikipedia article",
      "status": "ground",
      "note": "The UVM Alfa Aesar niobium powder SDS prints 4927 °C for the boiling point, which differs from the 4744 °C in the infobox. The SDS value is not used here.",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Boiling point row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, pure niobium",
      "value": 264.784,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium",
        "temperature": "not stated in the infobox"
      },
      "method": "Value printed in the infobox of the Wikipedia article",
      "status": "ground",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Specific heat capacity row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, pure niobium",
      "value": 53.7,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium",
        "temperature": "not stated in the infobox"
      },
      "method": "Value printed in the infobox of the Wikipedia article",
      "status": "ground",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Thermal conductivity row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, C-103 at 811 °C",
      "value": 38.1,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103, fully recrystallised",
        "temperature": "811 °C (1600 °F)",
        "unit_in_source": "W/m°C, printed in parentheses after the Btu/hr-ft2-°F/ft value of 22.0"
      },
      "method": "Value printed in a manufacturer datasheet; W/m°C is numerically the same as W/(m·K)",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Thermal Properties table, K column, row 1600°F (811°C)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, C-103 at 1304 °C",
      "value": 44.7,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103, fully recrystallised",
        "temperature": "1304 °C (2380 °F)",
        "unit_in_source": "W/m°C, printed in parentheses after the value of 25.8"
      },
      "method": "Value printed in a manufacturer datasheet; W/m°C is numerically the same as W/(m·K)",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Thermal Properties table, K column, row 2380°F (1304°C)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, pure niobium at 20 °C",
      "value": 7.07,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium",
        "temperature": "20 °C",
        "unit_in_source": "7.07 × 10⁻⁶ /K"
      },
      "method": "Value printed in the infobox of the Wikipedia article",
      "status": "ground",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Thermal expansion row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, pure niobium",
      "value": 105,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "form": "pure unalloyed niobium",
        "temperature": "not stated in the infobox"
      },
      "method": "Value printed in the infobox of the Wikipedia article",
      "status": "ground",
      "source": "wikipedia-niobium",
      "where": "Infobox, Physical properties, Young's modulus row",
      "source_detail": {
        "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
        "url": "https://en.wikipedia.org/wiki/Niobium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, C-103 at 20 °C",
      "value": 90,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temperature": "20 °C",
        "unit_in_source": "90 x 10 3 MPa"
      },
      "method": "Value printed in a manufacturer datasheet, Physical properties at 20 °C",
      "status": "ground",
      "source": "stainless-c103",
      "where": "Physical properties at 20 °C, Young's modulus line",
      "source_detail": {
        "title": "Niobium C-103 (UNS R04295) technical datasheet, Stainless SA, Dannemarie-sur-Crete",
        "id": "UNS R04295; ASTM B652, B654, B655; AMS 7852, AMS 7857",
        "url": "https://www.stainless.eu/wp-content/uploads/2024/11/Niobium-C103%C2%AE-EN.pdf",
        "kind": "datasheet",
        "license": "manufacturer datasheet, general information (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, C-103 at room temperature (minimum)",
      "value": 276,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "air",
        "product_form": "bar, rod, sheet and plate (Smiths)",
        "basis": "minimum value",
        "unit_in_source": "40 ksi (276)"
      },
      "method": "Minimum value printed in a manufacturer datasheet, for room and elevated temperature tensile testing when fully recrystallised",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row RT, column YS ksi (MPa)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, C-103 at 538 °C (minimum)",
      "value": 172,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "vacuum",
        "temperature": "538 °C (1000 °F)",
        "basis": "minimum value",
        "unit_in_source": "25 ksi (172)"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row 1000°F (538°C), column YS ksi (MPa)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, C-103 at 1093 °C (minimum)",
      "value": 124,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "vacuum",
        "temperature": "1093 °C (2000 °F)",
        "basis": "minimum value",
        "unit_in_source": "18 ksi (124)"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row 2000°F (1093°C), column YS ksi (MPa)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, C-103 at 1300 °C (laser powder bed fusion)",
      "value": 130,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "C103 (Nb-10Hf-1Ti), laser powder bed fusion",
        "form": "as printed then stress relieved at 900 °C for 1 h in high vacuum",
        "temperature": "1300 °C",
        "test": "uniaxial tension in high vacuum"
      },
      "method": "Value printed in a NASA Glenn Research Center presentation (TMS 2025), in the comparison table of C103 and Nb521",
      "status": "ground",
      "note": "This is an additive-manufactured lab result, not the wrought datasheet value, so it is not directly comparable with the rows above.",
      "source": "nasa-c103-nb521",
      "where": "Comparing Performance, Cost and Other Properties slide, row Yield Strength at 1300 °C [MPa], column C103",
      "source_detail": {
        "title": "A Comparison of Niobium Alloys C103 and Nb521, Brizes and Milner, NASA Glenn Research Center, TMS 2025",
        "id": "NASA NTRS 20250002178",
        "url": "https://ntrs.nasa.gov/api/citations/20250002178/downloads/A%20Comparison%20of%20Nb%20Alloys%20C103%20and%20Nb521.pdf",
        "year": 2025,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, C-103 at room temperature (minimum)",
      "value": 386,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "air",
        "basis": "minimum value",
        "unit_in_source": "56 ksi (386)"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row RT, column UTS ksi (MPa)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, C-103 at 1093 °C (minimum)",
      "value": 172,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "vacuum",
        "temperature": "1093 °C (2000 °F)",
        "basis": "minimum value",
        "unit_in_source": "25 ksi (172)"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row 2000°F (1093°C), column UTS ksi (MPa)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at room temperature, C-103 (minimum)",
      "value": 20,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "air",
        "basis": "minimum value"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row RT, column Elongation (%)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation at 1093 °C, C-103 (minimum)",
      "value": 30,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "vacuum",
        "temperature": "1093 °C (2000 °F)",
        "basis": "minimum value"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row 2000°F (1093°C), column Elongation (%)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, C-103 at 1371 °C (minimum)",
      "value": 55,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "Niobium C-103",
        "temper": "fully recrystallised",
        "atmosphere": "vacuum",
        "temperature": "1371 °C (2500 °F)",
        "basis": "minimum value",
        "unit_in_source": "8 ksi (55)"
      },
      "method": "Minimum value printed in a manufacturer datasheet",
      "status": "ground",
      "source": "smiths-c103",
      "where": "Mechanical Properties (minimum) table, row 2500°F (1371°C), column YS ksi (MPa)",
      "source_detail": {
        "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
        "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
        "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier datasheet (cited, not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Air at high temperature, uncoated niobium and C-103",
      "headline": "Niobium begins to oxidise in air at 200 °C, and unprotected C-103 needs a coating above 800 °C.",
      "effect": "Wikipedia states that the metal begins to oxidise in air at 200 °C. The Golden Sunbird technical guide says the primary limitation of C-103 is its oxidation resistance in air at elevated temperatures, that its oxide at 800 °C is Nb2O5 followed by HfO2, and that extended service above 800 °C in oxidising environments requires protective coatings.",
      "rating": "severe",
      "conditions": {
        "basis": "air; no exposure duration printed for the 200 °C start",
        "alloy": "C-103 and pure niobium"
      },
      "source": "wikipedia-niobium",
      "where": "Chemical properties, Oxidation paragraph (the 200 °C statement); the 800 °C statement is in section 8.1 of the Golden Sunbird guide"
    },
    {
      "environment": "Air at high temperature, silicide-coated C-103",
      "headline": "A silicide coating raises the usable temperature of C-103 to about 1400 °C.",
      "effect": "A NASA Glenn presentation says C103 is typically used with a high-temperature oxidation-resistant silicide coating, Si-20Cr-20Fe with the tradename R512E, which enables operation up to 1400 °C. The same slide gives MoSi2 coatings as 1600 °C for Nb521.",
      "rating": "moderate",
      "conditions": {
        "coating": "R512E silicide, NbSi2 per NASA table",
        "basis": "maximum operating temperature with coating, as printed"
      },
      "source": "nasa-c103-nb521",
      "where": "Introduction slide, and Comparing Performance table row Maximum Operating Temp. with Coating"
    },
    {
      "environment": "Aqueous acids and hot chemical environments",
      "headline": "Niobium resists several mineral acids but is attacked by hot concentrated sulfuric acid and by hydrofluoric acid.",
      "effect": "Wikipedia states that niobium resists corrosion by aqua regia, hydrochloric, sulfuric, nitric and phosphoric acids, and is attacked by hot concentrated sulfuric acid, hydrofluoric acid and hydrofluoric/nitric acid mixtures.",
      "rating": "low",
      "conditions": {
        "basis": "general statement in the Wikipedia article; no concentration or temperature table read"
      },
      "source": "wikipedia-niobium",
      "where": "Chemical properties, Corrosion paragraph"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Niobium powder (Alfa Aesar product, UVM copy of the SDS) is classified as Flammable solids, Category 1 (H228), with signal word Danger and precautionary statement P210 (keep away from heat and ignition sources). The substance's CLP entry is Flam. Sol. 1 (H228).",
        "ghs": [
          "H228"
        ],
        "source": "uvm-niobium-sds",
        "where": "Section 2.1 and 2.2 (Signal Word, Hazard Statements); Section 3.1 Substances table"
      },
      {
        "text": "PubChem aggregates ECHA C&L notifications for niobium: 34 % of 529 company reports give H228 (Flammable solid) with signal word Danger. Reports stating that the substance does not meet GHS criteria make up 58 % (307 of 529).",
        "ghs": [
          "H228"
        ],
        "source": "pubchem-niobium",
        "where": "GHS Classification section, aggregated information from 7 notifications to the ECHA C&L Inventory"
      },
      {
        "text": "The H.C. Starck datasheet for C-103 bar and rod gives the hazard statement under the EU advertising directives as None.",
        "ghs": [],
        "source": "hcs-c103",
        "where": "Physical Properties page, row Hazards identification in Advertising"
      }
    ],
    "failure_risks": [
      {
        "mode": "Air oxidation of unprotected niobium alloy at high temperature",
        "trigger": "Exposure to air above 200 °C for pure niobium, and above about 800 °C for C-103 without a coating",
        "consequence": "A non-protective oxide scale forms, Nb2O5 first and HfO2 later in C-103 (Golden Sunbird guide, citing Kathiravan et al.). The guide also reports internal oxidation along grain boundaries in the 800 to 850 °C range.",
        "severity": "critical",
        "source": "wikipedia-niobium",
        "where": "Chemical properties, Oxidation statement at 200 °C; the rest from section 3.4 and 8.1 of the Golden Sunbird guide"
      },
      {
        "mode": "Interstitial contamination by hydrogen, nitrogen and oxygen",
        "trigger": "Contact with hydrogen at 200 °C, nitrogen at 400 °C or residual oxygen in the melt",
        "consequence": "Products are interstitial and nonstoichiometric (Wikipedia). The C-103 datasheet limits O to 225 ppm max, N to 150 ppm max and H to 10 ppm max, which are the limits that prevent this contamination in production.",
        "severity": "moderate",
        "source": "hcs-c103",
        "where": "Chemical Characteristics table (O, N, H max rows); the reaction temperatures are in the Wikipedia article, Chemical properties section"
      },
      {
        "mode": "Fire from fine niobium powder",
        "trigger": "Handling niobium powder in air, which the SDS classes as a flammable solid",
        "consequence": "Flammable solid, Category 1 (H228); the SDS says to use approved Class D extinguishers and not water or foam.",
        "severity": "moderate",
        "source": "uvm-niobium-sds",
        "where": "Section 5.1 Extinguishing media"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Keep niobium powder away from heat, hot surfaces, sparks and open flames, and extinguish fires with a Class D agent, not water or foam (UVM copy of the SDS, P210 and Section 5.1).",
        "source": "uvm-niobium-sds",
        "where": "Section 2.2 precautionary statement P210; Section 5.1"
      },
      {
        "text": "Specify the oxygen, nitrogen and hydrogen limits of C-103 on the order. The H.C. Starck datasheet gives max O 225 ppm, N 150 ppm and H 10 ppm.",
        "source": "hcs-c103",
        "where": "Chemical Characteristics table"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "propulsion-and-tanks",
      "device": "Liquid-rocket thruster nozzle in C-103 alloy",
      "example": "Wikipedia says C-103 is used for liquid-rocket thruster nozzles, such as the descent engine of the Apollo Lunar Modules. H.C. Starck lists rocket nozzle applications with temperatures up to 2700 °F (1482 °C).",
      "source": "wikipedia-niobium",
      "where": "Alloys section, paragraph on C-103 (Niobium-based alloys); also hcs-c103 Applications row"
    },
    {
      "application": "structures",
      "device": "Steel microalloy (ferroniobium, high-strength low-alloy steel)",
      "example": "The USGS 2026 summary estimates that steels took about 77 % of U.S. niobium consumption, and superalloys about 23 %.",
      "source": "usgs-mcs2026-niobium",
      "where": "Domestic Production and Use paragraph"
    },
    {
      "application": "in-space-manufacturing",
      "device": "C103 parts made by laser powder bed fusion",
      "example": "NASA Glenn printed C103 by laser powder bed fusion and tested it in high vacuum to 1500 °C; its yield at 1300 °C was 130 MPa.",
      "source": "nasa-c103-nb521",
      "where": "Laser Powder Bed Fusion and Elevated Temperature Uniaxial Tensile Testing slides; Comparing Performance table"
    }
  ],
  "supply": [
    {
      "subject": "Niobium (mine production)",
      "producers": [
        {
          "country": "Brazil",
          "share_percent": 93,
          "year": 2025
        },
        {
          "country": "Canada",
          "share_percent": 5,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "The USGS says niobium was recycled when niobium-bearing steels and superalloys were recycled, but scrap recovery for niobium content was negligible. It may have been as much as 20 % of apparent consumption.",
      "substitutes": [
        "USGS: ceramic matrix composites, molybdenum, tantalum and tungsten in superalloys; molybdenum, tantalum and titanium in stainless and high-strength steels; molybdenum and vanadium in high-strength low-alloy steels. Performance loss or higher cost may follow."
      ],
      "source": "usgs-mcs2026-niobium",
      "where": "Events, Trends and Issues paragraph (Brazil about 93 %, Canada 5 %, 2025); World Mine Production and Reserves table (Brazil 104,000 t, Canada 6,000 t, Congo (Kinshasa) 970 t, world total 112,000 t, 2025e, niobium content); Recycling; Substitutes"
    },
    {
      "subject": "Niobium (United States import dependence and imports)",
      "abundance": "USGS: world resources of niobium are more than adequate to supply projected needs, most identified resources are pyrochlore in carbonatite deposits outside the United States. World reserves are more than 21,000,000 t, and Brazil holds 14,000,000 t.",
      "producers": [
        {
          "country": "Brazil (imports of ferroniobium and niobium metal, 2021 to 2024)",
          "share_percent": 65,
          "year": 2024
        },
        {
          "country": "Canada (imports of ferroniobium and niobium metal, 2021 to 2024)",
          "share_percent": 31,
          "year": 2024
        }
      ],
      "critical_lists": [],
      "substitutes": [],
      "source": "usgs-mcs2026-niobium",
      "where": "Salient Statistics table (net import reliance 100 % in 2025e; imports for consumption 10,000 t in 2025e; apparent consumption 9,900 t); Import Sources (2021 to 2024); World Resources paragraph"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "USGS Mineral Commodity Summaries 2026: Niobium (Columbium)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf",
      "year": 2026
    },
    {
      "title": "Wikipedia: Niobium",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Niobium",
      "year": 2026
    },
    {
      "title": "UVM copy of Alfa Aesar niobium powder safety data sheet (revision 2, 19 February 2021)",
      "type": "sds",
      "url": "https://www.uvm.edu/cosmolab/msds/niobiumpowdermsds.pdf",
      "year": 2021
    },
    {
      "title": "PubChem compound record for niobium (CID 23936), GHS classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23936/JSON?heading=GHS+Classification"
    },
    {
      "title": "H.C. Starck product data sheet PD-7054, Niobium C-103 alloy bar and rod (issue 15.05.2018)",
      "type": "datasheet",
      "url": "https://www.hcstarcksolutions.com/wp-content/uploads/PD-7054_0-Nb-C-103-Bar-Rod.pdf",
      "year": 2018
    },
    {
      "title": "Smiths High Performance technical datasheet, Niobium C-103 (revision 18.02.2025)",
      "type": "datasheet",
      "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
      "year": 2025
    },
    {
      "title": "Stainless SA datasheet, Niobium C-103 (UNS R04295)",
      "type": "datasheet",
      "url": "https://www.stainless.eu/wp-content/uploads/2024/11/Niobium-C103%C2%AE-EN.pdf"
    },
    {
      "title": "Golden Sunbird Metals technical guide, Niobium C-103 Alloy (UNS R04295/Nb-10Hf-1Ti)",
      "type": "datasheet",
      "url": "https://gsalloy.com/niobium-c-103-alloy-uns-r04295-nb-10hf-1ti-a-technical-guide/"
    },
    {
      "title": "Brizes and Milner, A Comparison of Niobium Alloys C103 and Nb521, NASA Glenn, TMS 2025",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20250002178/downloads/A%20Comparison%20of%20Nb%20Alloys%20C103%20and%20Nb521.pdf",
      "year": 2025
    },
    {
      "title": "NIST Atomic Weights and Isotopic Compositions for All Elements, niobium row",
      "type": "database",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Nb&all=all&ascii=html"
    }
  ],
  "gaps": [
    "UNS R04200 and R04210 (unalloyed reactor and commercial grade niobium, ASTM B392): the ASTM B392 listing page opened did not print the grade numbers, and the MakeItFrom page could not be fetched, so these codes are not listed as designations.",
    "EN, EN name, DIN, JIS and W.Nr. designations for niobium or C-103: no page printing one for this grade was read in this run.",
    "Critical-mineral list status: the USGS 2026 niobium summary prints no critical-mineral list, and the EU critical raw materials list was not opened, so critical_lists is empty.",
    "No atomic-oxygen erosion yield, outgassing or total mass loss, and no radiation test was found for niobium or C-103 in space.",
    "Electrical resistivity of pure niobium (152 nΩ·m at 0 °C, Wikipedia) is not entered: the unit nΩ·m is not in the site's unit registry, so the value was left out.",
    "Pseudo-creep rate of L-PBF C103 (4.82 %/h at 1300 °C and 50 MPa, NASA) is not entered: no canonical property name or unit exists for it in the site's property canon.",
    "Wrought C-103 tensile values at 2000 °F from the H.C. Starck datasheet (YS 16 ksi, UTS 21 ksi) and the Golden Sunbird sheet and plate minimums (UTS 385 MPa, YS 275 MPa, elongation 20 %) were read but not entered; the Smiths minimum table was used instead, and ksi values are not in the site's unit registry.",
    "Coefficient of thermal expansion for C-103: the Stainless SA datasheet prints 6,84 x 10-6 m/m.°C with a decimal comma, and the H.C. Starck datasheet prints 3.8 to 4.5 x 10-6/°F; neither was entered because the unit or the number format could not be matched cleanly.",
    "Hardness, Mohs 6.0 and Vickers 870 to 1320 MPa for pure niobium (Wikipedia), were read but not entered: no canonical hardness property name exists in the property canon.",
    "Atomic weights of hafnium and titanium were not read from a NIST page, so the alloy recipe gives only shares for those two elements.",
    "Golden Sunbird sheet minimums and the ASTM B654 composition limits are used in the identity and recipe text only, not as property values.",
    "Niobium production process: Wikipedia says electron beam melting under vacuum is the method used by the two major distributors, and the USGS text gives no process steps, so the recipe line does not describe the reduction of ore to metal.",
    "Mine production process, smelting of niobium concentrates: not read from a primary source."
  ],
  "story": {
    "why": "Niobium is a refractory metal with a melting point of 2477 °C (pure) and a body-centred cubic structure. Its alloy C-103, with 10 wt% hafnium and 1 wt% titanium, keeps useful strength at high temperature, which is why it is used for liquid-rocket thruster nozzles. Smiths High Performance gives minimum tensile yield strengths of 276 MPa at room temperature and 124 MPa at 1093 °C in vacuum. Most niobium goes into steel: the USGS 2026 summary estimates steels at about 77 % of U.S. consumption.",
    "uses": [
      {
        "where": "Rocket nozzles",
        "line": "C-103 is the thruster nozzle alloy for liquid-rocket engines, including the descent engine of the Apollo Lunar Modules (Wikipedia). H.C. Starck lists rocket nozzle applications up to 1482 °C."
      },
      {
        "where": "Steel",
        "line": "Niobium is an important addition to high-strength low-alloy steels, including pipeline steel (Wikipedia). The USGS 2026 summary estimates steels at about 77 % of U.S. consumption."
      },
      {
        "where": "Additive manufacturing",
        "line": "NASA Glenn printed C103 by laser powder bed fusion and reported a yield strength of 130 MPa at 1300 °C after stress relief."
      }
    ],
    "can_do": [
      {
        "label": "Carry load when hot",
        "line": "The minimum yield strength of recrystallised C-103 in vacuum is 124 MPa at 1093 °C and 55 MPa at 1371 °C (Smiths datasheet).",
        "benchmark": "yield_strength",
        "scope": "material",
        "value": "124 MPa yield at 1093 °C"
      },
      {
        "label": "Carry heat",
        "line": "C-103 has a thermal conductivity of 38.1 W/(m·K) at 811 °C and 44.7 W/(m·K) at 1304 °C (Smiths datasheet, W/m°C).",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "38.1 W/(m·K) at 811 °C"
      },
      {
        "label": "Weight",
        "line": "C-103 has a density of 8.86 g/cm3 at 20 °C (Stainless SA datasheet). Pure niobium has a density of 8.582 g/cm3 (Wikipedia).",
        "benchmark": "density",
        "scope": "material",
        "value": "8.86 g/cm3"
      },
      {
        "label": "Melting",
        "line": "C-103 melts at 2350 plus or minus 50 °C (Stainless and Smiths datasheets). Pure niobium melts at 2477 °C (Wikipedia).",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "2350 °C"
      },
      {
        "label": "Stiffness",
        "line": "C-103 has a Young's modulus of 90 GPa at 20 °C (Stainless SA datasheet). Pure niobium has 105 GPa (Wikipedia).",
        "benchmark": "elastic_modulus",
        "scope": "material",
        "value": "90 GPa"
      }
    ],
    "compare": "NASA Glenn reports that Nb521 (Nb-5W-2Mo-1Zr) has about 70 MPa higher yield strength than C103 across the tested temperature range, and about 100 times the creep resistance at 1300 °C and 50 MPa. Its estimated raw material cost is about 100 USD/kg against about 500 USD/kg for C103 (NASA slide table), so C103 is the costlier raw material. The three rows below compare density, melting point and thermal conductivity of niobium and C-103 only.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Specify the oxygen, nitrogen and hydrogen limits on the order, as the C-103 datasheet does.",
      "Keep niobium powder away from heat and ignition sources, and use a Class D extinguisher (UVM SDS).",
      "Protect C-103 with a silicide coating for any service above 800 °C in air (Golden Sunbird guide)."
    ],
    "good_for": [
      "High-temperature load in vacuum: 124 MPa minimum yield at 1093 °C for recrystallised C-103 (Smiths).",
      "Thruster nozzles: C-103 is the standard liquid-rocket nozzle alloy named in Wikipedia and the H.C. Starck datasheet.",
      "Heat conduction at temperature: 38.1 W/(m·K) at 811 °C for C-103 (Smiths)."
    ],
    "watch_out": [
      "Oxidation: niobium begins to oxidise in air at 200 °C, and C-103 needs a coating above 800 °C (Wikipedia, Golden Sunbird).",
      "Powder: niobium powder is a Category 1 flammable solid (H228) and needs a Class D extinguisher (UVM SDS).",
      "Supply: Brazil mines about 93 % of world niobium and the United States imports all of its niobium material (USGS 2026).",
      "No space outgassing, erosion yield or radiation data for niobium or C-103 were found in the sources read."
    ],
    "verdict": "Niobium is a dense refractory metal (8.582 g/cm3 pure, melting point 2477 °C) whose C-103 alloy holds a minimum 124 MPa yield strength at 1093 °C in vacuum and is the standard thruster nozzle alloy. It oxidises in air from 200 °C and needs a coating above 800 °C, and the metal powder is a flammable solid. Its supply is concentrated in Brazil, and this profile has no sourced space-environment test data.",
    "recipe": {
      "line": "Niobium is a single-element metal (Nb, atomic number 41) with a body-centred cubic structure (Wikipedia). C-103 is a niobium base alloy with 9.0 to 11.0 wt% hafnium and 0.7 to 1.3 wt% titanium, and maximum 0.7 wt% zirconium, 0.5 wt% tantalum and 0.5 wt% tungsten, as printed in the H.C. Starck and Smiths datasheets. Electron beam melting under vacuum is the method used by the two major niobium distributors (Wikipedia), because niobium reacts with oxygen and must be worked in vacuum or inert gas.",
      "parts": [
        {
          "name": "Niobium",
          "symbol": "Nb",
          "role": "The base metal, the balance of the alloy. Pure niobium has a density of 8.582 g/cm3 and a melting point of 2477 °C (Wikipedia).",
          "atoms": 1,
          "atomic_weight": 92.906
        },
        {
          "name": "Hafnium",
          "symbol": "Hf",
          "role": "Solid-solution strengthener that raises the recrystallisation temperature and forms HfO2 scales that add some oxidation resistance (Golden Sunbird guide).",
          "share_note": "9.0 to 11.0 wt% (ASTM B654 limit, H.C. Starck and Smiths)"
        },
        {
          "name": "Titanium",
          "symbol": "Ti",
          "role": "The 1 wt% nominal alloying addition in C-103 (Wikipedia).",
          "share_note": "0.7 to 1.3 wt% (ASTM B654 limit, H.C. Starck and Smiths)"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The powder is a flammable solid in the supplier safety data sheet. The bulk alloy datasheet gives no hazard statement.",
        "points": [
          {
            "label": "Niobium powder",
            "line": "The UVM copy of the Alfa Aesar safety data sheet classifies niobium powder as Flammable solid, Category 1 (H228), with the signal word Danger. PubChem's ECHA aggregate shows H228 in 34 % of 529 reports."
          },
          {
            "label": "C-103 bar and rod",
            "line": "The H.C. Starck datasheet gives the hazard statement under the EU advertising directives as None."
          }
        ],
        "level": 1,
        "verdict": "Flammable as powder, not hazardous as bulk alloy"
      },
      {
        "title": "If it fails",
        "lead": "The failure routes here are oxidation in air and contamination by gases. The sources give no test of these in space.",
        "points": [
          {
            "label": "Oxidation",
            "line": "Niobium begins to oxidise in air at 200 °C, and unprotected C-103 needs a coating for extended service above 800 °C."
          },
          {
            "label": "Gas pickup",
            "line": "Hydrogen at 200 °C, nitrogen at 400 °C and oxygen all form interstitial products, so the C-103 datasheet sets maximum oxygen, nitrogen and hydrogen contents."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-25",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 21,
    "unreachable": 2,
    "caveats": 6,
    "note": "Values were read by an AI assistant on 2026-10-25 from the pages and PDFs named in each entry (PDFs extracted with pdftotext; the USGS and NASA values from the PDF text). Unreachable: MatWeb C-103 pages (Cloudflare check) and the MakeItFrom R04200 page. Caveats: the C-103 mechanical values are minimums from one datasheet (Smiths), so they are not typical values; the 130 MPa yield at 1300 °C is an additive-manufactured lab result; the density of pure niobium is from Wikipedia while the SDS prints 8.57 g/cm3; the boiling point differs between the Wikipedia infobox (4744 °C) and the powder SDS (4927 °C); the 800 °C oxidation threshold comes from a supplier guide, not a test report."
  },
  "sources": {
    "wikipedia-niobium": {
      "title": "Niobium, Wikipedia (infobox physical properties, chemical properties, production, alloys, applications)",
      "url": "https://en.wikipedia.org/wiki/Niobium",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "usgs-mcs2026-niobium": {
      "title": "Mineral Commodity Summaries 2026, Niobium (Columbium), February 2026",
      "id": "USGS MCS 2026, prepared by Chad A. Friedline",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "uvm-niobium-sds": {
      "title": "Safety data sheet, niobium powder (Alfa Aesar product ALFAA40510), copy hosted by the University of Vermont, revision 2",
      "id": "CAS 7440-03-1, EC 231-113-5, revision 19-Feb-2021",
      "url": "https://www.uvm.edu/cosmolab/msds/niobiumpowdermsds.pdf",
      "year": 2021,
      "kind": "datasheet",
      "license": "supplier safety data sheet (cited, not reproduced)"
    },
    "pubchem-niobium": {
      "title": "PubChem compound record: Niobium (CID 23936), GHS Classification section",
      "id": "CID 23936, ECHA C&L Inventory aggregated notifications",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23936/JSON?heading=GHS+Classification",
      "kind": "database",
      "license": "PubChem (NCBI), public domain; sections attributed to ECHA"
    },
    "stainless-c103": {
      "title": "Niobium C-103 (UNS R04295) technical datasheet, Stainless SA, Dannemarie-sur-Crete",
      "id": "UNS R04295; ASTM B652, B654, B655; AMS 7852, AMS 7857",
      "url": "https://www.stainless.eu/wp-content/uploads/2024/11/Niobium-C103%C2%AE-EN.pdf",
      "kind": "datasheet",
      "license": "manufacturer datasheet, general information (cited, not reproduced)"
    },
    "smiths-c103": {
      "title": "Niobium C-103 technical datasheet, Smiths High Performance, revision 18.02.2025",
      "id": "Related specifications ASTM B652, B654, B655, AMS 7852, AMS 7857; C-103 a proprietary product of Materion",
      "url": "https://www.smithshp.com/assets/pdf/niobium/niobium-c-103-english.pdf",
      "year": 2025,
      "kind": "datasheet",
      "license": "supplier datasheet (cited, not reproduced)"
    },
    "hcs-c103": {
      "title": "Niobium C-103 alloy bar and rod, product data sheet PD-7054, H.C. Starck Inc.",
      "id": "PD-7054, issue 0-15.05.2018",
      "url": "https://www.hcstarcksolutions.com/wp-content/uploads/PD-7054_0-Nb-C-103-Bar-Rod.pdf",
      "year": 2018,
      "kind": "datasheet",
      "license": "manufacturer datasheet (cited, not reproduced)"
    },
    "golden-sunbird-c103": {
      "title": "Niobium C-103 Alloy (UNS R04295/Nb-10Hf-1Ti): A Technical Guide, Golden Sunbird Metals",
      "id": "ASTM B654 composition limits; oxidation section 3.4; coatings section 8.1",
      "url": "https://gsalloy.com/niobium-c-103-alloy-uns-r04295-nb-10hf-1ti-a-technical-guide/",
      "kind": "web",
      "license": "supplier web page (cited, not reproduced)"
    },
    "nasa-c103-nb521": {
      "title": "A Comparison of Niobium Alloys C103 and Nb521, Brizes and Milner, NASA Glenn Research Center, TMS 2025",
      "id": "NASA NTRS 20250002178",
      "url": "https://ntrs.nasa.gov/api/citations/20250002178/downloads/A%20Comparison%20of%20Nb%20Alloys%20C103%20and%20Nb521.pdf",
      "year": 2025,
      "kind": "report",
      "license": "NASA public document"
    },
    "nist-atomic-weights-nb": {
      "title": "NIST Atomic Weights and Isotopic Compositions for All Elements, niobium",
      "id": "NIST standard atomic weight table, Nb 92.906",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Nb&all=all&ascii=html",
      "kind": "database",
      "license": "US government data"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/niobium/"
}