{
  "spore": "profile",
  "id": "aluminium-boron-carbide-composite",
  "spore_version": "0.2",
  "family": "aluminium-boron-carbide-composites",
  "name": "Aluminium-boron carbide composite (Metamic, BORAL)",
  "abbreviation": "Al-B4C",
  "role": "neutron absorber for spent-fuel storage racks, transport casks and shields",
  "category": "shielding",
  "type": "spot-shields",
  "summary": "Aluminium-boron carbide composite is an aluminium matrix loaded with boron carbide (B4C) particles, which absorb neutrons. The NRC's 2020 review describes Metamic, an aluminium 6061 matrix with 15, 31 or 40 wt% B4C, with a yield strength of 157 MPa at 15 wt% B4C and 207 MPa at 40 wt% B4C. NASA Langley's 2023 ground study of Al6061 with 50 vol% B4C measured 75.5 % shielding of an indium-foil neutron test.\n",
  "best_for": "Neutron absorber panels in spent-fuel pool racks and transport-cask baskets, where boron content matters (NRC 2020; Holtec)",
  "weakest_at": "Ductility at high B4C loading: elongation falls from 10.6 % at 15 wt% B4C to 1.0 % at 40 wt% (NRC Table 2); no flight data",
  "identity": {
    "formula": "Al + B4C (aluminium matrix with boron carbide particles; Metamic uses an aluminium 6061 matrix)",
    "designations": [
      {
        "system": "Trade name",
        "code": "Metamic",
        "source": "nrc-focht-2020",
        "where": "Section 4.1, Metamic title and first paragraph"
      }
    ],
    "source": "nrc-focht-2020",
    "where": "Section 4.1 (Metamic: aluminium 6061 matrix with ASTM C-750 Type I B4C particles); supplier mass fraction of B4C 15% to 50% (TRUNNANO product page)"
  },
  "tags": {
    "environments": [],
    "stresses": [
      "total-radiation-dose"
    ],
    "applications": [
      "radiation-shielding"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, Al + B4C board (supplier range)",
      "value": 2.5,
      "value_high": 2.65,
      "bound": "range",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "composition": "Al + B4C, B4C mass fraction 15% to 50% as printed",
        "basis": "at least 95% of theoretical density, as printed",
        "form": "board, hot rolled or hot isostatic pressed (product page)"
      },
      "method": "Range printed in a supplier product table",
      "status": "ground",
      "note": "The same page's description section prints about 2.5-2.7 g/cm3 for this material; the two ranges are kept as printed.",
      "source": "trunnano-b4c-al",
      "where": "Main Technical Parameters, Physical properties row",
      "source_detail": {
        "title": "Luoyang Tongrun Nano Technology (TRUNNANO), product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold under the RBOSCHCO name",
        "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/",
        "kind": "web",
        "license": "supplier web page, cited not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, Metamic 15 wt% B4C",
      "value": 157,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 15,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2 Average Mechanical Properties of Metamic for Various B4C Loadings, Yield Strength row",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, Metamic 31 wt% B4C",
      "value": 227,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 31,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Yield Strength row, 31% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, Metamic 40 wt% B4C",
      "value": 207,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 40,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Yield Strength row, 40% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Ultimate tensile strength, Metamic 15 wt% B4C",
      "value": 232,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 15,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Ultimate Strength row, 15% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Ultimate tensile strength, Metamic 31 wt% B4C",
      "value": 272,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 31,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Ultimate Strength row, 31% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Ultimate tensile strength, Metamic 40 wt% B4C",
      "value": 277,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 40,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Ultimate Strength row, 40% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation to failure, Metamic 15 wt% B4C",
      "value": 10.6,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 15,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Elongations row, 15% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation to failure, Metamic 31 wt% B4C",
      "value": 2.4,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 31,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Elongations row, 31% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation to failure, Metamic 40 wt% B4C",
      "value": 1,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "matrix": "aluminium 6061",
        "B4C_wt_percent": 40,
        "basis": "average, as printed; test temperature and specimen form not stated in Table 2"
      },
      "method": "Average mechanical properties as printed in the NRC review, citing the EPRI handbook",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 2, Elongations row, 40% column",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, Al + B4C board (supplier minimum)",
      "value": 110,
      "bound": "lower",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "minimum printed as 110 MPa or more",
        "composition": "Al + B4C board; matrix alloy not named on the page"
      },
      "method": "Minimum printed in a supplier product table; no test standard named",
      "status": "ground",
      "source": "trunnano-b4c-al",
      "where": "Main Technical Parameters, Mechanical properties, Yield strength row",
      "source_detail": {
        "title": "Luoyang Tongrun Nano Technology (TRUNNANO), product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold under the RBOSCHCO name",
        "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/",
        "kind": "web",
        "license": "supplier web page, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, Al + B4C board (supplier minimum)",
      "value": 200,
      "bound": "lower",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "basis": "minimum printed as 200 MPa or more; typical value 300 MPa or more, up to 440 MPa, as printed",
        "composition": "Al + B4C board; matrix alloy not named on the page"
      },
      "method": "Minimum printed in a supplier product table; no test standard named",
      "status": "ground",
      "note": "The page's description section prints a range of 200-440 MPa for the same material.",
      "source": "trunnano-b4c-al",
      "where": "Main Technical Parameters, Mechanical properties, Tensile strength row",
      "source_detail": {
        "title": "Luoyang Tongrun Nano Technology (TRUNNANO), product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold under the RBOSCHCO name",
        "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/",
        "kind": "web",
        "license": "supplier web page, cited not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation after fracture, Al + B4C board (supplier minimum)",
      "value": 1.8,
      "bound": "lower",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "minimum printed as 1.8% or more; typical value 2% to 3% as printed",
        "composition": "Al + B4C board; matrix alloy not named on the page"
      },
      "method": "Minimum printed in a supplier product table; no test standard named",
      "status": "ground",
      "source": "trunnano-b4c-al",
      "where": "Main Technical Parameters, Mechanical properties, Elongation after fracture row",
      "source_detail": {
        "title": "Luoyang Tongrun Nano Technology (TRUNNANO), product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold under the RBOSCHCO name",
        "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/",
        "kind": "web",
        "license": "supplier web page, cited not reproduced"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, pristine Al6061 control (113.0 +/- 7.2 Hv as printed)",
      "value": 113,
      "bound": "exact",
      "unit": "HV",
      "scope": "material",
      "conditions": {
        "material": "pristine Al6061 control, no B4C",
        "load": "500 gf",
        "dwell": "10 s"
      },
      "method": "Vickers hardness with a microhardness tester, as printed in Table 1",
      "status": "ground",
      "uncertainty": "+/- 7.2 as printed",
      "source": "nasa-b4c-al-2023",
      "where": "Table 1, Al6061 column",
      "source_detail": {
        "title": "Chu, Park, Wallace, Lum et al. 2023, B4C-Al Metal Matrix Composites for Extreme Space Environments (NASA/TM-20230003044, NASA Langley)",
        "id": "NASA/TM-20230003044 (NTRS 20230003044)",
        "url": "https://ntrs.nasa.gov/api/citations/20230003044/downloads/NASA-TM-20230003044revised.pdf",
        "year": 2023,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, Al6061 with 20 vol% B4C",
      "value": 157.6,
      "bound": "exact",
      "unit": "HV",
      "scope": "material",
      "conditions": {
        "material": "Al6061 with 20 vol% B4C, stir cast and hot rolled",
        "load": "500 gf",
        "dwell": "10 s"
      },
      "method": "Vickers hardness with a microhardness tester, as printed in Table 1",
      "status": "ground",
      "uncertainty": "+/- 7.7 as printed",
      "source": "nasa-b4c-al-2023",
      "where": "Table 1, 20%B4C/Al6061 column",
      "source_detail": {
        "title": "Chu, Park, Wallace, Lum et al. 2023, B4C-Al Metal Matrix Composites for Extreme Space Environments (NASA/TM-20230003044, NASA Langley)",
        "id": "NASA/TM-20230003044 (NTRS 20230003044)",
        "url": "https://ntrs.nasa.gov/api/citations/20230003044/downloads/NASA-TM-20230003044revised.pdf",
        "year": 2023,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, pristine Al6061 at room temperature",
      "value": 156,
      "bound": "exact",
      "unit": "W/mK",
      "scope": "material",
      "conditions": {
        "material": "pristine Al6061 control, no B4C",
        "temperature": "room temperature",
        "measurement": "laser flash analyzer"
      },
      "method": "Value printed in the text as about 156 W/mK; the composite values are shown only in Figure 7 and are not used",
      "status": "ground",
      "source": "nasa-b4c-al-2023",
      "where": "Section 3 (thermal conductivity paragraph), pristine Al6061 sentence",
      "source_detail": {
        "title": "Chu, Park, Wallace, Lum et al. 2023, B4C-Al Metal Matrix Composites for Extreme Space Environments (NASA/TM-20230003044, NASA Langley)",
        "id": "NASA/TM-20230003044 (NTRS 20230003044)",
        "url": "https://ntrs.nasa.gov/api/citations/20230003044/downloads/NASA-TM-20230003044revised.pdf",
        "year": 2023,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "neutron_shielding_effectiveness",
      "label": "Neutron shielding, Al6061 with 50 vol% B4C (indium foil, percent shielded)",
      "value": 75.5,
      "bound": "exact",
      "unit": "% shielded",
      "scope": "material",
      "conditions": {
        "B4C_vol_percent": 50,
        "matrix": "Al6061",
        "test": "indium-foil activation with an Am-Be neutron source (4.5 MeV)",
        "comparison": "pristine Al6061 control shielded 1.1 % in the same test"
      },
      "method": "Percent shielded as printed in Table 2 (not converted)",
      "status": "ground",
      "source": "nasa-b4c-al-2023",
      "where": "Table 2, row NIA B4C 50% vol, % shielded column",
      "source_detail": {
        "title": "Chu, Park, Wallace, Lum et al. 2023, B4C-Al Metal Matrix Composites for Extreme Space Environments (NASA/TM-20230003044, NASA Langley)",
        "id": "NASA/TM-20230003044 (NTRS 20230003044)",
        "url": "https://ntrs.nasa.gov/api/citations/20230003044/downloads/NASA-TM-20230003044revised.pdf",
        "year": 2023,
        "kind": "report",
        "license": "NASA public document"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Long-term operating temperature, Al + B4C board (supplier limit)",
      "value": 400,
      "bound": "upper",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "long-term operating temperature as printed (400℃)",
        "composition": "Al + B4C board"
      },
      "method": "Limit printed in a supplier product table; the NRC review tested Metamic at 398 °C in air for up to 6,139 hours (see corrosion)",
      "status": "ground",
      "source": "trunnano-b4c-al",
      "where": "Main Technical Parameters, Thermal and shielding performance, long-term operating temperature row",
      "source_detail": {
        "title": "Luoyang Tongrun Nano Technology (TRUNNANO), product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold under the RBOSCHCO name",
        "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/",
        "kind": "web",
        "license": "supplier web page, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Modulus of elasticity, BORAL cermet with 1100 aluminium cladding",
      "value": 9,
      "bound": "exact",
      "unit": "msi",
      "scope": "material",
      "conditions": {
        "material": "BORAL aluminium-B4C cermet core with 1100 aluminium cladding",
        "temperature": "room temperature"
      },
      "method": "Room temperature mechanical properties as printed in Table 3, unit as printed",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 3 Room Temperature Mechanical Properties of BORAL, Modulus of elasticity row",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, BORAL cermet with 1100 aluminium cladding",
      "value": 10,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "material": "BORAL aluminium-B4C cermet core with 1100 aluminium cladding",
        "temperature": "room temperature"
      },
      "method": "Room temperature mechanical properties as printed in Table 3, unit as printed",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 3 Room Temperature Mechanical Properties of BORAL, Tensile strength row",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation, BORAL cermet with 1100 aluminium cladding",
      "value": 0.1,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "material": "BORAL aluminium-B4C cermet core with 1100 aluminium cladding",
        "temperature": "room temperature"
      },
      "method": "Room temperature mechanical properties as printed in Table 3",
      "status": "ground",
      "source": "nrc-focht-2020",
      "where": "Table 3 Room Temperature Mechanical Properties of BORAL, Elongation row",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    },
    {
      "benchmark": "compaction_density",
      "label": "Compaction density, BORAL cermet core (survey of 40 panels)",
      "value": 89.5,
      "value_high": 96.1,
      "bound": "range",
      "unit": "% of theoretical",
      "scope": "material",
      "conditions": {
        "material": "BORAL aluminium-B4C cermet core",
        "sample": "40 panels surveyed by Brooks and Perkins"
      },
      "method": "Range printed in the NRC review (average 93 percent); cermets do not typically reach theoretical density",
      "status": "ground",
      "note": "Average printed as 93 percent of theoretical density.",
      "source": "nrc-focht-2020",
      "where": "Section 4.3.1 Density and Composition",
      "source_detail": {
        "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
        "id": "NRC ML19353A030",
        "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
        "year": 2020,
        "kind": "report",
        "license": "US government work, public domain"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Simulated BWR water at 90.5 °C (195 °F), mill-finished Metamic",
      "headline": "Mill-finished Metamic lost 3 percent of its weight in BWR water over 9,020 hours, with pitting; anodized Metamic lost none.",
      "effect": "The 15 wt% mill-finished coupons showed a 3-percent weight loss after 9,020 hours in addition to pitting. Anodized coupons showed no measurable weight loss in either BWR or PWR water. The NRC attributes the pitting in the qualification tests to surface contaminants from manufacturing.",
      "rating": "moderate",
      "conditions": {
        "temperature": "90.5 °C (195 °F)",
        "exposure": "about 2,000, 4,000, 6,000 and 8,000 hours planned; 9,020 hours reported",
        "test": "accelerated general and pitting corrosion, coupons in mill-finished and anodized conditions"
      },
      "source": "nrc-focht-2020",
      "where": "Section 4.1.1.5 (Corrosion Testing Results); summary in Section 4.4.1 (general corrosion)"
    },
    {
      "environment": "Simulated PWR water (2,500 ppm boron as boric acid) at 90.5 °C, Metamic coupons",
      "headline": "Mill-finished Metamic showed no measurable weight loss in PWR water.",
      "effect": "The NRC reports that PWR coupons showed no detectable weight loss, and that encapsulated coupons showed none in either water after 9,020 hours. Pitting still appeared on some mill-finished coupons, mostly from surface contaminants.",
      "rating": "low",
      "conditions": {
        "temperature": "90.5 °C (195 °F)",
        "boron_ppm": 2500,
        "exposure": "9,020 hours for encapsulated coupons"
      },
      "source": "nrc-focht-2020",
      "where": "Section 4.1.1.5 (Corrosion Testing Results); summary in Section 4.4.1.1"
    },
    {
      "environment": "Galvanic contact with Inconel 718, 304L stainless steel and Zircaloy 2",
      "headline": "Pitting occurred where Metamic was clamped to 304L stainless steel.",
      "effect": "Bimetallic coupons showed localized pitting on mill-finished Metamic, attributed to surface contaminants from extrusion. One anodized 31 wt% coupon clamped to 304L pitted after 9,030 hours, attributed to surface contamination. Galvanic pitting is a known risk when aluminium alloys couple with 304 and 304L stainless steel.",
      "rating": "low",
      "conditions": {
        "exposure": "inspected after 4,124 and 9,030 hours",
        "couples": "Inconel 718, 304L stainless steel, Zircaloy 2"
      },
      "source": "nrc-focht-2020",
      "where": "Section 4.1.1.5 (Galvanic corrosion paragraph); Section 4.4.1.2 (Pitting)"
    },
    {
      "environment": "Demineralized BWR water, BORAL aluminium-B4C cermet",
      "headline": "BORAL corroded at 1.91 mg/cm2/yr (0.28 mil per year), two-sided, in BWR water.",
      "effect": "Brooks and Perkins reported a two-sided corrosion rate of 1.91 mg/cm2/yr (0.28 mil per year) for BORAL in BWR water. The NRC expects rates in BWR water to be somewhat higher than in PWR water because of the higher pH without boron.",
      "rating": "low",
      "conditions": {
        "water": "demineralized BWR water",
        "product": "BORAL aluminium-B4C cermet"
      },
      "source": "nrc-focht-2020",
      "where": "Section 4.4.1.1 (general corrosion, BORAL sentence)"
    },
    {
      "environment": "Air at 398 °C (750 °F) for up to 6,139 hours, plus 2,000 hours more, Metamic coupons",
      "headline": "No detectable change in Metamic dimensions, density or areal density after long exposure at 398 °C.",
      "effect": "After 2,133, 4,124 and 6,139 hours at 398 °C in air, the NRC reports no detectable change in dimensions, density, dry weight or areal density. Tensile properties of 15 wt% coupons stayed within one standard deviation of unexposed coupons. Welded coupons showed lower strength and elongation.",
      "rating": "low",
      "conditions": {
        "temperature": "398 °C (750 °F)",
        "atmosphere": "air",
        "exposure": "2,133, 4,124 and 6,139 hours, plus 2,000 hours more on the last set"
      },
      "source": "nrc-focht-2020",
      "where": "Section 4.1.1.3 (Long-Term Elevated Temperature Testing)"
    },
    {
      "environment": "Gamma radiation, 4.5x10^9 to 1.5x10^11 rads, Metamic 15 wt% and 31 wt%",
      "headline": "Gamma doses up to 1.5x10^11 rads changed no dimension, density or hardness, but pitting appeared from 3.6x10^10 rads.",
      "effect": "The NRC reports no measurable change in dimension, dry weight, density, B-10 areal density or hardness up to 1.5x10^11 rads, which the NRC equates to about 40 years of fuel-rack exposure. Localized pitting appeared at 3.6x10^10 rads and above. Ultimate tensile strength fell, yield strength rose and elongation fell over the dose range; the NRC calls these changes not significant because the material is not structural.",
      "rating": "moderate",
      "conditions": {
        "dose_range": "4.5x10^9 to 1.5x10^11 rads gamma",
        "equivalent_exposure": "about 40 years of fuel-rack exposure at 1.5x10^11 rads",
        "fast_neutron_fluence": "5.8x10^19 n/cm2 at the maximum dose"
      },
      "source": "nrc-focht-2020",
      "where": "Section 4.1.1 (EPRI report summary), radiation exposure paragraph, and Figures 4 and 5"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Supplier safety data sheet for boron carbide powder (Stanford Advanced Materials, CAS 12069-32-8, revised 10/11/2022): signal word Warning. The powder is harmful if inhaled, causes skin irritation and serious eye irritation, and may cause respiratory irritation. This sheet covers the B4C powder ingredient, not the finished composite.",
        "ghs": [
          "H332",
          "H315",
          "H319",
          "H335"
        ],
        "source": "sds-stanford-b4c",
        "where": "Section 2, Hazards identification, Label elements"
      }
    ],
    "failure_risks": [
      {
        "mode": "Loss of ductility at high B4C loading",
        "trigger": "Raising Metamic from 31 wt% to 40 wt% B4C",
        "consequence": "Elongation to failure fell from 2.4 % at 31 wt% to 1.0 % at 40 wt% (NRC Table 2).",
        "severity": "moderate",
        "source": "nrc-focht-2020",
        "where": "Table 2, Elongations row"
      },
      {
        "mode": "Poor bonding of a high-loading cermet",
        "trigger": "B4C loading above 50 % by weight in the BORAL cermet core",
        "consequence": "Higher B4C loadings sinter poorly because there is too little aluminium powder, and one BORAL manufacturer limits B4C to 50 percent to keep the cermet bonded to its cladding.",
        "severity": "moderate",
        "source": "nrc-focht-2020",
        "where": "Section 3.2 (BORAL, cermet core paragraph)"
      },
      {
        "mode": "Localized pitting from surface contamination or galvanic contact",
        "trigger": "Mill-finished surfaces in BWR water, or coupling with 304L stainless steel",
        "consequence": "Mill-finished Metamic lost 3 percent of its weight in BWR water over 9,020 hours, with pitting (NRC).",
        "severity": "moderate",
        "source": "nrc-focht-2020",
        "where": "Section 4.1.1.5 (Corrosion Testing Results)"
      }
    ],
    "side_effects": [
      {
        "text": "Adding B4C lowers the thermal conductivity of Al6061. NASA reports a gradual decrease with B4C content, against about 156 W/mK for pristine Al6061 at room temperature; the composite values are shown only in a graph.",
        "affects": "Heat paths through the panel",
        "source": "nasa-b4c-al-2023",
        "where": "Results, thermal conductivity paragraph and Figure 7"
      }
    ],
    "handling": [
      {
        "text": "Machining or grinding the material makes B4C dust. The powder SDS says to avoid breathing dust (P261), and lists H332 and H335. Use extraction at the cutting station.",
        "source": "sds-stanford-b4c",
        "where": "Section 2, Hazards identification and precautionary statements (P261)"
      },
      {
        "text": "Store the boards at 20 ℃ ± 2 ℃ and at or below 10% relative humidity, as the supplier specifies.",
        "source": "trunnano-b4c-al",
        "where": "Description, 6. Instructions for use (storage temperature and relative humidity)"
      },
      {
        "text": "Storage and disposal of the powder: the SDS gives P405 (store locked up) and P501 (dispose of contents under local regulations).",
        "source": "sds-stanford-b4c",
        "where": "Section 2, Precautionary statements"
      }
    ],
    "mitigations": [
      {
        "text": "Anodizing protects Metamic: anodized coupons showed no measurable weight loss in BWR or PWR water, and cleaning before anodizing removes the impurities that cause pitting.",
        "source": "nrc-focht-2020",
        "where": "Section 4.1.1.5 (Corrosion Testing Results) and summary in Section 4.4.1"
      }
    ]
  },
  "uses": [
    {
      "application": "radiation-shielding",
      "device": "Neutron absorber panels in spent-fuel pool storage racks (BORAL, Metamic and Boralcan)",
      "example": "The NRC reports that BORAL is used in about 60 percent of domestic spent fuel pools, and Metamic and Boralcan together in about 20 percent.",
      "source": "nrc-focht-2020",
      "where": "Section 1 (Executive Summary) and Section 3.2"
    },
    {
      "application": "radiation-shielding",
      "device": "Fuel basket of the HI-STAR 180 transport cask (uses Metamic-HT, a Holtec variant)",
      "example": "Holtec cites docket 71-9325 for the HI-STAR 180 transport cask, whose fuel basket uses Metamic-HT, a Holtec variant of Metamic.",
      "source": "holtec-metamic",
      "where": "Why Metamic? section (docket reference)"
    },
    {
      "application": "radiation-shielding",
      "device": "Al6061 plate with 50 vol% B4C for neutron shielding (ground test, not flown)",
      "example": "NASA Langley reports that 50 vol% B4C in Al6061 raised neutron shielding effectiveness more than 110 times over pristine Al6061. The study is a ground test with an Am-Be source and a radiation model, not a flight result.",
      "source": "nasa-b4c-al-2023",
      "where": "Abstract and Table 2"
    }
  ],
  "supply": [
    {
      "subject": "Aluminium (matrix)",
      "abundance": "Not read in this run.",
      "producers": [
        {
          "country": "China",
          "share_percent": 60.8,
          "year": 2025
        },
        {
          "country": "India",
          "share_percent": 5.7,
          "year": 2025
        },
        {
          "country": "Russia",
          "share_percent": 5.3,
          "year": 2025
        },
        {
          "country": "Canada",
          "share_percent": 4.5,
          "year": 2025
        },
        {
          "country": "United Arab Emirates",
          "share_percent": 3.6,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: about 3.6 million tons of aluminium was recovered from purchased scrap in the United States in 2025.",
      "substitutes": [
        "USGS: composites, magnesium, steel and titanium can substitute for aluminium in ground transportation uses (the chapter's substitution list)."
      ],
      "source": "usgs-mcs2026-aluminum",
      "where": "World Smelter Production table, 2025e column (shares calculated by Space Mushroom against the printed world total of 74,000 thousand metric tons, rounded); Recycling; Substitutes"
    },
    {
      "subject": "Boron (feedstock for the B4C particles)",
      "abundance": "USGS 2026: boron does not occur in nature as an element. It is sold as borates and boric oxide.",
      "producers": [
        {
          "country": "Turkey",
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 Final List of Critical Minerals (boron added in the 2025 list)",
          "listed": true
        }
      ],
      "recycling": "Not stated in the USGS boron chapter read.",
      "substitutes": [
        "USGS: substitution for boron is possible in detergents, enamels, insulation and soaps. This applies to boron in general, not to B4C."
      ],
      "source": "usgs-mcs2026-boron",
      "where": "Events, Trends and Issues (critical minerals paragraph); Production table, Turkey refined borates 2025; Import Sources (2021-24: Turkey 90%); Substitutes"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "NRC report, Assessment of Aluminum-Based Neutron Absorber Materials Qualification Testing and Surveillance Monitoring Programs (May 2020)",
      "type": "report",
      "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
      "year": 2020
    },
    {
      "title": "Holtec International, neutron absorber material (Metamic) product page",
      "type": "datasheet",
      "url": "https://holtecinternational.com/products-and-services/innovative-technologies/neutronabsorbermaterial/"
    },
    {
      "title": "NASA/TM-20230003044, B4C-Al Metal Matrix Composites for Extreme Space Environments",
      "type": "report",
      "url": "https://ntrs.nasa.gov/citations/20230003044",
      "year": 2023
    },
    {
      "title": "Luoyang Tongrun Nano (TRUNNANO) product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold as RBOSCHCO",
      "type": "datasheet",
      "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/"
    },
    {
      "title": "Stanford Advanced Materials safety data sheet, Boron Carbide, CAS 12069-32-8 (revised 10/11/2022)",
      "type": "sds",
      "url": "https://samaterials.com/tds/1721380172-bc3503.pdf",
      "year": 2022
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Boron",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Aluminum",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf",
      "year": 2026
    }
  ],
  "gaps": [
    "No manufacturer density value for Metamic was found. The NRC review and the Holtec page give none; the only density is the supplier range of 2.5 to 2.65 g/cm3 for a board whose matrix alloy is not named.",
    "No elastic modulus, thermal conductivity or coefficient of thermal expansion for Metamic or for the B4C-Al6061 composite was printed as a number in a source read in this run. NASA's tensile values (Figures 5 and 6) and thermal conductivity values (Figure 7) are graphs only and are not used.",
    "Metamic B-10 areal density specification and neutron absorption cross section were not found in any page read in this run. The NRC text gives the B-10 areal density only as a measured-change result.",
    "Neutron absorption rate of 90 percent or more (supplier page) names no test standard, composition or thickness, so it is not used as a property.",
    "The TRUNNANO page names no test standard, test temperature or matrix alloy for its mechanical values. Its description section prints a different density range (about 2.5-2.7 g/cm3) and tensile range (200-440 MPa) from its table; both are recorded.",
    "Metamic-HT, a Holtec variant with an alumina-reinforced matrix alloy, is a different grade and is not profiled here.",
    "No flight, vacuum or thermal-vacuum result for the composite was found. The NASA study is a ground neutron test with modelling.",
    "Atomic weights of boron, carbon and aluminium were not read in a fetched page, so the recipe parts carry no atomic_weight.",
    "The USGS aluminium chapter read in this run does not state whether aluminium is on a critical-minerals list, so no critical_lists entry is given for aluminium.",
    "Boron carbide production shares were not found: the USGS boron table prints the world total as XX, so no producer shares are calculated for boron.",
    "Recycling of boron-carbide composites was not stated in any source read.",
    "Hazard statements for the finished composite were not found. The SDS read covers the boron carbide powder only.",
    "Radiation and ageing results give trends and no numeric values for tensile properties after irradiation (the NRC reports the trends in text and in Figures 4 and 5).",
    "Oxidation and corrosion of the composite in air at high temperature beyond the 398 C exposure were not searched.",
    "PubChem GHS classification for boron carbide could not be read in this run, because PubChem returned a verification page, so the hazard entry rests on the supplier SDS alone.",
    "An open-access MDPI Metals paper on B4C/Al6061 composites could not be read in this run (HTTP 403), so its tensile, density and thermal data are not used."
  ],
  "story": {
    "why": "Aluminium-boron carbide composite puts boron carbide particles into an aluminium matrix, so a structural-looking panel can also absorb neutrons. Metamic and BORAL are the two products the NRC reviewed for spent-fuel storage. NASA Langley tested an aluminium 6061 version with boron carbide for space radiation shielding in a ground study. The composite is chosen when neutron absorption has to be built into the material, not added as a separate shield.",
    "uses": [
      {
        "where": "Spent fuel pool racks",
        "line": "The NRC reports that BORAL is used in about 60 percent of US spent fuel pools, and Metamic and Boralcan together in about 20 percent."
      },
      {
        "where": "Transport cask fuel basket",
        "line": "Holtec cites docket 71-9325 for the HI-STAR 180 transport cask, whose fuel basket uses Metamic-HT, a Holtec variant."
      },
      {
        "where": "Ground test for space radiation",
        "line": "NASA Langley tested Al6061 with 50 vol% B4C in a ground neutron test, and its model suggests it also helps against galactic cosmic rays. It is not a flight result."
      }
    ],
    "can_do": [
      {
        "label": "Neutron absorption",
        "line": "At 50 vol% B4C in Al6061, NASA measured 75.5 % shielded in an indium-foil neutron test. NASA reports a shielding effectiveness more than 110 times that of pristine Al6061.",
        "benchmark": "neutron_shielding_effectiveness",
        "scope": "material"
      },
      {
        "label": "Yield strength",
        "line": "Metamic averages a yield strength of 157 MPa at 15 wt% B4C and 227 MPa at 31 wt% B4C, according to NRC Table 2.",
        "benchmark": "yield_strength",
        "scope": "material"
      },
      {
        "label": "Hardness",
        "line": "NASA measured 157.6 Hv for Al6061 with 20 vol% B4C, against 113.0 Hv for pristine Al6061.",
        "benchmark": "vickers_hardness",
        "scope": "material"
      },
      {
        "label": "Temperature limit",
        "line": "The supplier gives a long-term operating limit of 400 °C for its board.",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "400 °C"
      }
    ],
    "compare": "Compared with pristine Al6061, B4C raises hardness and lowers thermal conductivity. NASA reports Vickers hardness of 157.6 Hv at 20 vol% B4C against 113.0 Hv for pristine Al6061, and about 156 W/mK for pristine Al6061 at room temperature, with the composite values shown only in a figure. Within the Metamic loadings, more B4C means less stretch: elongation is 10.6 % at 15 wt% and 1.0 % at 40 wt%, while yield strength is 157 MPa at 15 wt% and 207 MPa at 40 wt%.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Yield strength",
        "benchmark": "yield_strength",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Machining or grinding the material makes B4C dust. Use extraction and avoid breathing the dust (SDS statement P261).",
      "Store the boards at 20 ℃ ± 2 ℃ and at or below 10% relative humidity, as the supplier specifies.",
      "Expect little stretch at high loading: the 40 wt% grade elongates 1.0 % before it fails."
    ],
    "good_for": [
      "Neutron absorption in spent fuel racks. NRC reports BORAL in about 60 percent of US spent fuel pools.",
      "Neutron absorption with some strength. Metamic at 15 wt% B4C has a yield strength of 157 MPa and 10.6 % elongation."
    ],
    "watch_out": [
      "Ductility falls with B4C content: 2.4 % elongation at 31 wt% and 1.0 % at 40 wt%.",
      "Pitting in BWR water and in galvanic contact with 304L stainless steel. Anodizing helps.",
      "No flight data. The NASA result is a ground neutron test and a model."
    ],
    "verdict": "The composite is an established neutron absorber in nuclear storage, backed by the NRC's 2020 review of qualification tests. Its space role rests on one NASA ground study. Density is a supplier range, and the Metamic tensile values are averages, so confirm the grade and loading before using any number.",
    "recipe": {
      "line": "Aluminium-boron carbide composite is an aluminium matrix that holds boron carbide (B4C) particles. Wikipedia notes that boron carbide absorbs neutrons without forming long-lived radionuclides, which is why it is used in nuclear shielding. Metamic is made by powder metallurgy from high-purity aluminium powder and nuclear grade boron carbide (ASTM C750 Type 1), per Holtec, then extruded into preforms and hot rolled to final thickness (NRC). BORAL is a different form: a cermet core of B4C and aluminium powder in 1100 aluminium cladding, hot rolled into plate or sheet (NRC).",
      "parts": [
        {
          "name": "Aluminium",
          "symbol": "Al",
          "role": "The matrix. Metamic uses aluminium 6061; the BORAL core uses 1100 aluminium powder and cladding. It holds the particles and carries the load.",
          "share_note": "balance (the rest of the mass)",
          "source": "nrc-focht-2020",
          "where": "Section 3.2 and Section 4.1"
        },
        {
          "name": "Boron carbide",
          "symbol": "B4C",
          "role": "The neutron absorber. Boron captures neutrons, so the B4C content sets how much neutron absorption the panel gives.",
          "share_percent": 15,
          "share_high": 50,
          "source": "trunnano-b4c-al",
          "where": "Main Technical Parameters, Material composition (mass fraction 15% to 50%)"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The finished board is a solid metal-matrix material, but machining or grinding it releases B4C dust. The hazard statements we read are for the B4C powder, not the composite.",
        "points": [
          {
            "label": "Dust",
            "line": "Cutting, grinding or machining makes fine dust. Use extraction and avoid breathing the dust (SDS statement P261)."
          },
          {
            "label": "Inhalation",
            "line": "The powder SDS gives H332 (harmful if inhaled) and H335 (may cause respiratory irritation)."
          }
        ],
        "level": 1,
        "verdict": "Dust hazard when machining"
      },
      {
        "title": "If a part fails",
        "lead": "These numbers come from NRC Table 2 and describe average Metamic test results.",
        "points": [
          {
            "label": "Stretch before breaking",
            "line": "At 31 wt% B4C, Metamic stretches 2.4 % before it breaks. At 40 wt% it stretches 1.0 %. At 15 wt% it stretches 10.6 %."
          },
          {
            "label": "Pitting",
            "line": "Mill-finished Metamic lost 3 percent of its weight in BWR water over 9,020 hours, with pitting. Anodized Metamic lost none."
          }
        ],
        "level": 2,
        "verdict": "Ductility falls as B4C rises"
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 22,
    "unreachable": 13,
    "caveats": 4,
    "note": "Written in this run from pages and PDFs read in this run: NRC 2020 (PDF, read as text), NASA/TM-20230003044 (PDF, read as text), the Holtec product page, the TRUNNANO product page, the Stanford boron carbide SDS (PDF), and the USGS MCS 2026 boron and aluminum chapters (PDF). verify-values found 9 of 22 values in their source text and 0 not found. The 13 NRC values (Table 2, Table 3 and the compaction density range) could not be fetched by the script, because nrc.gov returns HTTP 403 to scripted requests; they were read by hand from the same PDF in this run. Supplier values are unverified manufacturer or reseller claims with no test standard named. NASA tensile and thermal conductivity values appear only in figures and are not used. The Wikipedia boron carbide article was read in this run for the composition and nuclear-use sentence in the recipe."
  },
  "sources": {
    "nrc-focht-2020": {
      "title": "Assessment of Aluminum-Based Neutron Absorber Materials: Materials Qualification Testing and Surveillance Monitoring Programs (Eric M. Focht, U.S. NRC Office of Nuclear Regulatory Research, May 2020)",
      "id": "NRC ML19353A030",
      "url": "https://www.nrc.gov/docs/ML1935/ML19353A030.pdf",
      "year": 2020,
      "kind": "report",
      "license": "US government work, public domain"
    },
    "holtec-metamic": {
      "title": "Holtec International, neutron absorber material (Metamic) product page, Why Metamic? section",
      "url": "https://holtecinternational.com/products-and-services/innovative-technologies/neutronabsorbermaterial/",
      "kind": "web",
      "license": "manufacturer web page, cited not reproduced"
    },
    "nasa-b4c-al-2023": {
      "title": "Chu, Park, Wallace, Lum et al. 2023, B4C-Al Metal Matrix Composites for Extreme Space Environments (NASA/TM-20230003044, NASA Langley)",
      "id": "NASA/TM-20230003044 (NTRS 20230003044)",
      "url": "https://ntrs.nasa.gov/api/citations/20230003044/downloads/NASA-TM-20230003044revised.pdf",
      "year": 2023,
      "kind": "report",
      "license": "NASA public document"
    },
    "trunnano-b4c-al": {
      "title": "Luoyang Tongrun Nano Technology (TRUNNANO), product page, Aluminum-based Boron Carbide (Al-B4C) Composite Material, sold under the RBOSCHCO name",
      "url": "https://www.rboschco.com/products/metals-and-alloys/aluminum-based-boron-carbide-al-b4c-composite-material/",
      "kind": "web",
      "license": "supplier web page, cited not reproduced"
    },
    "sds-stanford-b4c": {
      "title": "Stanford Advanced Materials, Safety Data Sheet, Boron Carbide (CAS 12069-32-8), revised 10/11/2022",
      "url": "https://samaterials.com/tds/1721380172-bc3503.pdf",
      "year": 2022,
      "kind": "datasheet",
      "license": "vendor safety data sheet, cited not reproduced"
    },
    "usgs-mcs2026-boron": {
      "title": "USGS Mineral Commodity Summaries 2026, Boron",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf",
      "kind": "report",
      "license": "US government work, public domain"
    },
    "usgs-mcs2026-aluminum": {
      "title": "USGS Mineral Commodity Summaries 2026, Aluminum",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf",
      "kind": "report",
      "license": "US government work, public domain"
    },
    "wikipedia-boron-carbide": {
      "title": "Wikipedia, Boron carbide (article read in this run for composition and nuclear use)",
      "url": "https://en.wikipedia.org/wiki/Boron_carbide",
      "kind": "web",
      "license": "CC BY-SA 4.0, cited not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/aluminium-boron-carbide-composite/"
}