Tellurium copper Cu-Te

spore: profile
id: tellurium-copper
spore_version: 0.2
family: copper-alloys
name: Tellurium copper
abbreviation: Cu-Te
role: free-machining electrical conductor
category: metals
type: copper-alloys
summary: Tellurium copper, UNS C14500, is copper with 0.40 to 0.70 % tellurium and 0.004 to 0.012 % phosphorus, added so that the metal machines much more easily while keeping high electrical conductivity. Wieland Concast gives a density of 8.94 g/cm3, 93 % IACS electrical conductivity and 355 W/(m·K) thermal conductivity at 20 °C, with minimum tensile strengths of 260 MPa in the H02 temper and 330 MPa in H04. Its tellurium brings a dust hazard when it is machined.
best_for: 'Free-machining electrical parts that need copper-level conductivity: 93 % IACS with a machinability rating of 85'
weakest_at: 'Corrosion data and dust safety: no quantitative corrosion test was found, and machining releases tellurium-bearing dust'
identity:
  formula: Cu with 0.40 to 0.70 % Te and 0.004 to 0.012 % P (ASTM B301 chemistry; copper minimum 99.90 %, including silver and tellurium)
  source: concast-c14500
  where: 'Chemical composition table, ASTM B301/B301M-13(2020) as printed by Wieland Concast: Cu 99.90 min, P 0.004-0.012, Te 0.40-0.70'
  designations:
    - system: UNS
      code: C14500
      source: concast-c14500
      where: Header and chemical composition table
    - system: ASTM
      code: B301
      note: free-cutting copper rod, bar, wire and shapes, B301/B301M-13(2020)
      source: concast-c14500
      where: Similar or equivalent specification table
tags:
  environments: []
  stresses: []
  applications:
    - electronics-and-chips
    - mechanisms
properties:
  - benchmark: density
    label: Density, tellurium copper C14500
    value: 8.94
    unit: g/cm3
    scope: material
    conditions:
      grade: C14500
      temperature: 20 °C
      unit_in_source: 0.323 lb/in3 at 68 °F
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Density
  - benchmark: melting_point
    label: Melting point, liquidus
    value: 1080
    unit: °C
    scope: material
    conditions:
      grade: C14500
      basis: liquidus
      unit_in_source: 1976 °F
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Melting point liquidus
  - benchmark: melting_point
    label: Melting point, solidus
    value: 1051
    unit: °C
    scope: material
    conditions:
      grade: C14500
      basis: solidus
      unit_in_source: 1924 °F
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Melting point solidus
  - benchmark: electrical_conductivity
    label: Electrical conductivity, IACS
    value: 93
    unit: '%IACS'
    scope: material
    conditions:
      grade: C14500
      temperature: 68 °F
      temper: not stated in the datasheet row
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Electrical conductivity, US customary column
  - benchmark: electrical_conductivity
    label: Electrical conductivity, metric
    value: 0.539
    unit: MS/cm
    scope: material
    conditions:
      grade: C14500
      temperature: 20 °C
      unit_in_source: MegaSiemens/cm
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Electrical conductivity, metric column
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C
    value: 355
    unit: W/(m·K)
    scope: material
    conditions:
      grade: C14500
      temperature: 20 °C
      unit_in_source: 205 Btu/sq ft/ft hr/°F at 68 °F; the metric unit is printed as W/m
    method: Value printed in a manufacturer datasheet. The metric unit is printed as W/m and is written here as W/(m·K); the paired Btu value, 205 Btu/(ft·h·°F), is about 355 W/(m·K) by Space Mushroom's check
    status: ground
    note: The datasheet prints the metric unit as W/m. The unit is written as W/(m·K) because the paired Btu value gives the same number.
    source: concast-c14500
    where: Physical properties table, row Thermal conductivity
  - benchmark: cte
    label: Coefficient of thermal expansion, 20 to 100 °C
    value: 16.5
    unit: ppm/K
    scope: material
    conditions:
      grade: C14500
      temperature_range: 20 to 100 °C
      unit_in_source: 16.5 · 10-6 per °C
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Coefficient of thermal expansion 68-212 F (metric 20-100 C)
  - benchmark: cte
    label: Coefficient of thermal expansion, 20 to 300 °C
    value: 17.1
    unit: ppm/K
    scope: material
    conditions:
      grade: C14500
      temperature_range: 20 to 300 °C
      unit_in_source: 17.1 · 10-6 per °C
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Coefficient of thermal expansion 68-572 F (metric 20-300 C)
  - benchmark: specific_heat
    label: Specific heat capacity at 20 °C
    value: 385.5
    unit: J/(kg·K)
    scope: material
    conditions:
      grade: C14500
      temperature: 20 °C
      unit_in_source: 385.5 J/kg at 20 °C; 0.092 Btu/lb/°F at 68 °F
    method: Value printed in a manufacturer datasheet; the datasheet prints J/kg, and the heat-capacity unit J/(kg·K) is used here
    status: ground
    source: concast-c14500
    where: Physical properties table, row Specific heat capacity
  - benchmark: elastic_modulus
    label: Modulus of elasticity in tension
    value: 117212
    unit: MPa
    scope: material
    conditions:
      grade: C14500
      unit_in_source: 17000 ksi
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Modulus of elasticity in tension
  - benchmark: shear_modulus
    label: Modulus of rigidity
    value: 44127
    unit: MPa
    scope: material
    conditions:
      grade: C14500
      unit_in_source: 6400 ksi
    method: Value printed in a manufacturer datasheet (physical properties provided by CDA)
    status: ground
    source: concast-c14500
    where: Physical properties table, row Modulus of rigidity
  - benchmark: yield_strength
    label: Yield strength at 0.5 % extension, H02 half hard
    value: 205
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C14500
      temper: H02 half hard
      size_range: 1/16 in to 1/4 in diameter rod
      measure: 0.5 % extension under load, minimum
      unit_in_source: 30 ksi
    method: Minimum value printed in a manufacturer datasheet, from ASTM B301/B301M-13(2020)
    status: ground
    source: concast-c14500
    where: Mechanical properties table, H02 half hard, size range 1/16 in to 1/4 in, Yield strength column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, H02 half hard, rod 1/16 to 1/4 in
    value: 260
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C14500
      temper: H02 half hard
      size_range: 1/16 in to 1/4 in diameter rod
      unit_in_source: 38 ksi
    method: Minimum value printed in a manufacturer datasheet, from ASTM B301/B301M-13(2020)
    status: ground
    source: concast-c14500
    where: Mechanical properties table, H02 half hard, size range 1/16 in to 1/4 in, Tensile strength column
  - benchmark: elongation
    label: Elongation, H02 half hard, rod 1/16 to 1/4 in
    value: 8
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: C14500
      temper: H02 half hard
      size_range: 1/16 in to 1/4 in diameter rod
      gauge: 4 times diameter or specimen thickness
    method: Minimum value printed in a manufacturer datasheet, from ASTM B301/B301M-13(2020)
    status: ground
    note: The next size range, over 1/4 in to 2 5/8 in, is printed with 12 % minimum elongation for the same temper.
    source: concast-c14500
    where: Mechanical properties table, H02 half hard, size range 1/16 in to 1/4 in, Elongation column
  - benchmark: yield_strength
    label: Yield strength at 0.5 % extension, H04 hard
    value: 275
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C14500
      temper: H04 hard
      size_range: 1/16 in to 1/4 in, round rod only
      measure: 0.5 % extension under load, minimum
      unit_in_source: 40 ksi
    method: Minimum value printed in a manufacturer datasheet, from ASTM B301/B301M-13(2020)
    status: ground
    source: concast-c14500
    where: Mechanical properties table, H04 hard, size range 1/16 in to 1/4 in, Yield strength column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, H04 hard, rod 1/16 to 1/4 in
    value: 330
    bound: lower
    unit: MPa
    scope: material
    conditions:
      grade: C14500
      temper: H04 hard
      size_range: 1/16 in to 1/4 in, round rod only
      unit_in_source: 48 ksi
    method: Minimum value printed in a manufacturer datasheet, from ASTM B301/B301M-13(2020)
    status: ground
    source: concast-c14500
    where: Mechanical properties table, H04 hard, size range 1/16 in to 1/4 in, Tensile strength column
  - benchmark: elongation
    label: Elongation, H04 hard, rod 1/16 to 1/4 in
    value: 4
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: C14500
      temper: H04 hard
      size_range: 1/16 in to 1/4 in, round rod only
      gauge: 4 times diameter or specimen thickness
    method: Minimum value printed in a manufacturer datasheet, from ASTM B301/B301M-13(2020)
    status: ground
    note: The next size range, over 1/4 in to 1 1/4 in, is printed with 8 % minimum elongation for the same temper.
    source: concast-c14500
    where: Mechanical properties table, H04 hard, size range 1/16 in to 1/4 in, Elongation column
  - benchmark: brinell_hardness
    label: Brinell hardness, typical, H02 half hard
    value: 76
    unit: BHN
    scope: material
    conditions:
      grade: C14500
      temper: H02 half hard
      load: 500 kg
      basis: typical value, not a minimum
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: concast-c14500
    where: Mechanical properties table, H02 half hard, Brinell hardness column
  - benchmark: brinell_hardness
    label: Brinell hardness, typical, H04 hard
    value: 81
    unit: BHN
    scope: material
    conditions:
      grade: C14500
      temper: H04 hard
      load: 500 kg
      basis: typical value, not a minimum
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: concast-c14500
    where: Mechanical properties table, H04 hard, Brinell hardness column
  - benchmark: machinability_rating
    label: Machinability rating, copper alloy C14500
    value: 85
    unit: '-'
    scope: material
    conditions:
      grade: C14500
      basis: rating printed by the datasheet, with CDA fabrication data
    method: Rating printed in a manufacturer datasheet (fabrication properties provided by CDA)
    status: ground
    note: Machinability is a rating, not a canonical property. The datasheet does not state the scale in the table, so the number is recorded as printed.
    source: concast-c14500
    where: Machinability table and Fabrication properties table, row Machinability rating
corrosion:
  - environment: General service, no test conditions (supplier statement)
    headline: A supplier says C14500 resists corrosion and hydrogen embrittlement, but gives no test data.
    effect: Anchor Bronze says C14500 combines resistance to hydrogen embrittlement with high electrical and thermal conductivity, and calls it the ideal choice for electrical applications that need extensive machining and corrosion resistance. The page gives no environment, test method or rate, and it says its values should not be used for specification.
    rating: unknown
    conditions:
      basis: supplier product page; no test conditions printed
    source: anchorbronze-c14500
    where: Product description paragraph and the note on specification use
risks:
  hazards:
    - text: 'PubChem summary for the element tellurium, from ECHA C&L notifications (527 company reports): signal word Danger; H332 (61.3%), H317 (45.7%), H362 (43.8%), H413 (45.5%), H360Df (39.5%), H319 (37.6%), H335 (37.4%), H360 (22.6%), H301 (18.6%). The record says classification varies with impurities, additives and form. The alloy holds only 0.40 to 0.70 % tellurium, and no alloy-specific safety data sheet was found.'
      ghs:
        - H301
        - H317
        - H319
        - H332
        - H335
        - H360
        - H360Df
        - H362
        - H413
      source: pubchem-tellurium
      where: GHS Classification section (ECHA C&L Inventory aggregate)
    - text: 'PubChem summary for copper (ECHA C&L Inventory, 3,463 company reports): signal word Warning; H302 (21.7%), H400 (43.1%), H410 (18.8%), H411 (22.5%). Copper is the matrix of the alloy.'
      ghs:
        - H302
        - H400
        - H410
        - H411
      source: pubchem-copper
      where: GHS Classification section (ECHA C&L Inventory aggregate)
    - text: 'NIOSH Pocket Guide, tellurium (as Te): OSHA PEL and NIOSH REL are each 0.1 mg/m3 as a time-weighted average; the IDLH is 25 mg/m3 as Te. No recommendation is printed for skin or eyes.'
      ghs: []
      source: niosh-npg-tellurium
      where: Exposure limits and Personal protection and sanitation sections
  failure_risks:
    - mode: Loss of cold-worked strength on annealing
      trigger: Heating into the annealing range printed by the datasheet, 800 to 1200 °F
      consequence: The datasheet gives the annealing range but no annealed strength for C14500, and the H02 and H04 minimums above apply only to the cold-worked tempers.
      severity: moderate
      source: concast-c14500
      where: Thermal properties table, row Annealing
    - mode: Poor weld joints
      trigger: Spot, seam or coated-metal arc welding
      consequence: The datasheet rates these methods not recommended, and rates butt welding and gas shielded arc welding as fair. Wikipedia says the alloy is not suited to welding, though gas shielded arc and resistance welding can be used.
      severity: moderate
      source: concast-c14500
      where: Fabrication properties table, Suitability column
  side_effects:
    - text: Machining releases chips and dust that contain tellurium and copper. The NIOSH and OSHA limit for tellurium is 0.1 mg/m3 as Te, which applies to the tellurium in the alloy's dust.
      affects: Machine operators and shop air
      source: niosh-npg-tellurium
      where: Exposure limits table
    - text: Copper is the matrix, so swarf and dust carry copper too. PubChem's copper record lists H400 and H410 (very toxic to aquatic life), which matters for how swarf is disposed of.
      affects: Waste and swarf disposal
      source: pubchem-copper
      where: GHS Classification section
  handling:
    - text: Specify the temper. The datasheet gives different minimum strengths for H02 and H04, and the size range changes the elongation minimum.
      source: concast-c14500
      where: Mechanical properties tables
    - text: Anneal in the printed range of 800 to 1200 °F and hot treat in the range of 1400 to 1600 °F, as printed in the datasheet's thermal properties.
      source: concast-c14500
      where: Thermal properties table, rows Annealing and Hot treatment
    - text: Keep tellurium dust below the NIOSH and OSHA time-weighted average of 0.1 mg/m3 as Te. No skin or eye recommendation is printed.
      source: niosh-npg-tellurium
      where: Exposure limits and Personal protection and sanitation
    - text: Soldering is rated excellent and brazing good. Spot, seam and coated-metal arc welding are rated not recommended.
      source: concast-c14500
      where: Fabrication properties table, Suitability column
  mitigations: []
uses:
  - application: electronics-and-chips
    device: Electrical connectors, transistor bases and switch parts
    example: Wieland Concast lists electrical connectors, motor parts, soldering copper, switch parts and transistor bases among the typical uses of C14500.
    source: concast-c14500
    where: Typical uses, Electrical column
  - application: mechanisms
    device: Screw-machine parts, forgings and soldering tips
    example: Wieland Concast lists screw machine products, forgings, soldering tips and welding torch tips among the typical industrial uses, and gives a machinability rating of 85.
    source: concast-c14500-web
    where: Typical uses, Industrial section; machinability rating table
supply:
  - subject: Copper
    producers:
      - country: Chile
        share_percent: 23
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 13.9
        year: 2025
      - country: Peru
        share_percent: 11.7
        year: 2025
      - country: China
        share_percent: 7.8
        year: 2025
      - country: Russia
        share_percent: 5.7
        year: 2025
    critical_lists:
      - list: U.S. Final 2025 List of Critical Minerals (copper added in 2025; USGS Mineral Commodity Summaries 2026)
        listed: true
    recycling: 'USGS: old scrap gave an estimated 160,000 tons of copper in 2025 and new scrap about 760,000 tons. Copper recovered from scrap supplied about 30 % of U.S. copper.'
    substitutes:
      - 'USGS: aluminum substitutes for copper in electrical equipment and power cable, and optical fiber substitutes for copper in telecommunications.'
    source: usgs-mcs2026-copper
    where: World Mine Production and Reserves table, mine production 2025e (world total 23,000 thousand t; shares calculated by Space Mushroom from Chile 5,300, Congo (Kinshasa) 3,200, Peru 2,700, China 1,800 and Russia 1,300 thousand t); Recycling; Substitutes
  - subject: Tellurium
    abundance: Recovered mainly from the anode slimes of copper electrolytic refining; more than 90 % of tellurium has come from that route (USGS). A crustal abundance was not read in this run.
    producers:
      - country: China
        share_percent: 80
        year: 2025
    critical_lists:
      - list: U.S. Final 2025 List of Critical Minerals (60 minerals; tellurium listed)
        listed: true
    recycling: 'USGS: tellurium was recycled from CdTe solar cells in the United States, but the quantity was limited because most of those cells were new.'
    substitutes:
      - 'USGS: in free-machining steels, bismuth, calcium, lead, phosphorus, selenium and sulfur can replace tellurium. The chapter names no substitute for tellurium in copper alloys.'
    source: usgs-mcs2026-tellurium
    where: Domestic Production and Use; World Resources; text on China's share of 2025 estimated global production (80 %); Recycling; Substitutes. Critical list status from the USGS about page (usgs-crit2025).
documents:
  - title: Wieland Concast technical data sheet, C14500 tellurium copper (ASTM B301 chemistry, mechanical and physical properties)
    type: datasheet
    url: https://www.concast.com/files/C14500.pdf
    year: 2026
  - title: Wieland Concast C14500 alloy product page (typical uses, specification list)
    type: datasheet
    url: https://www.concast.com/c14500.php
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Tellurium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tellurium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Copper'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
  - title: 'USGS: About the 2025 List of Critical Minerals (final list of 60 minerals)'
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
  - title: 'PubChem compound record: Tellurium (CID 6327182), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Tellurium
    year: 2026
  - title: 'PubChem compound record: Copper (CID 23978), GHS classification and molecular weight'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Copper
    year: 2026
  - title: 'NIOSH Pocket Guide to Chemical Hazards: Tellurium (as Te)'
    type: database
    url: https://www.cdc.gov/niosh/npg/npgd0587.html
    year: 2026
  - title: 'Anchor Bronze: C14500 alloy page (product description and specification note)'
    type: datasheet
    url: https://anchorbronze.com/c14500
  - title: 'Wikipedia: Tellurium copper (composition, machinability, welding)'
    type: database
    url: https://en.wikipedia.org/wiki/Tellurium_copper
gaps:
  - 'Corrosion: no quantitative corrosion, seawater, ammonia or stress-corrosion test for C14500 was found. The only corrosion statement is a supplier''s qualitative claim (Anchor Bronze), recorded as unknown. The Materials+ and OnlineMetals pages returned HTTP 403, so no second supplier statement was read.'
  - 'Designations: the EN number CW118C and the EN name CuTeP were seen only in search results. The makeitfrom and GlobalSpec pages returned HTTP 403, so these codes are not listed. BS C109 was not in a page read in this run.'
  - Phosphorus atomic weight was not read, so the recipe gives no atomic weight for phosphorus.
  - 'Space and vacuum: no NASA, NTRS, ESA or flight data for tellurium copper was found. A GlobalSpec listing that pairs C14500 with a UK aerospace bolt specification is weak evidence and was not used.'
  - Outgassing, atomic oxygen and radiation effects were not looked up for this alloy.
  - Electrical resistivity in ohm-metres and its temperature coefficient were not found as separate values. The conductivity is recorded from the datasheet in %IACS and MS/cm.
  - Crustal abundance of tellurium and copper in regolith was not looked up. The USGS tellurium chapter gives no crustal figure.
  - Tellurium production beyond China was not entered. The USGS refinery table is partly garbled in the text extract, so only the printed China share of 80 % is used.
  - Full ASTM B301 text was not opened. The minimum values come from the Wieland Concast datasheet, which prints them as ASTM B301/B301M-13(2020). Only the H02 and H04 tempers are given, and no annealed strength.
  - No alloy-specific safety data sheet for C14500 was found. Hazards rest on the PubChem summaries for tellurium and copper and on the NIOSH Pocket Guide entry for tellurium.
  - Brinell hardness and machinability are not canonical benchmarks, so they use the snake_case names brinell_hardness and machinability_rating.
  - 'Media: no licensed image of tellurium copper was fetched in this run, so no media entry is added.'
sources:
  concast-c14500:
    title: Technical data sheet, C14500 tellurium copper (Wieland Concast), chemical composition, mechanical and physical properties, fabrication properties (ASTM B301/B301M-13(2020); physical properties provided by CDA)
    id: UNS C14500; ASTM B124, B301; SAE J461, J463; Tellurium-bearing (PTE)
    url: https://www.concast.com/files/C14500.pdf
    year: 2026
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  concast-c14500-web:
    title: C14500 alloy, C145 tellurium copper, Wieland Concast product page
    url: https://www.concast.com/c14500.php
    year: 2026
    kind: datasheet
    license: Manufacturer web page (cited, not reproduced)
  wikipedia-tellurium-copper:
    title: Tellurium copper (Wikipedia)
    url: https://en.wikipedia.org/wiki/Tellurium_copper
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  usgs-mcs2026-tellurium:
    title: Mineral Commodity Summaries 2026, Tellurium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tellurium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-copper:
    title: Mineral Commodity Summaries 2026, Copper
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  pubchem-tellurium:
    title: 'PubChem compound record: Tellurium (CID 6327182), including ECHA C&L Inventory classification'
    id: CID 6327182; CAS 13494-80-9
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Tellurium
    year: 2026
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA and others
  pubchem-copper:
    title: 'PubChem compound record: Copper (CID 23978), including ECHA C&L Inventory classification'
    id: CID 23978; CAS 7440-50-8
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Copper
    year: 2026
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA and others
  niosh-npg-tellurium:
    title: 'NIOSH Pocket Guide to Chemical Hazards: Tellurium (as Te), CAS 13494-80-9'
    url: https://www.cdc.gov/niosh/npg/npgd0587.html
    year: 2026
    kind: handbook
    license: US government work, public domain
  anchorbronze-c14500:
    title: 'Anchor Bronze: C14500 alloy page (tellurium copper)'
    url: https://anchorbronze.com/c14500
    kind: web
    license: Supplier web page (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 20
  unreachable: 0
  caveats: 3
  note: 'Read by an AI assistant on 2026-10-26 from the Wieland Concast datasheet and product page, the USGS 2026 tellurium and copper chapters, the USGS 2025 critical-minerals page, the PubChem records for tellurium and copper (read through the PubChem REST service), the NIOSH Pocket Guide entry for tellurium, the Anchor Bronze C14500 page and Wikipedia. Not opened: makeitfrom, GlobalSpec, Materials+ and OnlineMetals (HTTP 403), matmatch (no DNS). Caveats: the metric thermal conductivity unit is printed as W/m; the strengths are supplier-datasheet minimums for one size range per temper; the corrosion statement is a supplier claim with no test conditions.'
story:
  recipe:
    line: Tellurium copper is copper with small additions of tellurium and phosphorus, in the composition set by ASTM B301 (as printed by Wieland Concast). Tellurium is added to copper mainly to improve machinability, and Wikipedia says machinability is improved while electrical conductivity and hot working behaviour are maintained.
    parts:
      - name: Copper
        symbol: Cu
        share_note: 99.90 % minimum, including silver and tellurium
        role: The matrix. It carries the electrical and thermal conductivity of the alloy.
        source: pubchem-copper
        where: Element record, molecular weight as printed by PubChem
      - name: Tellurium
        symbol: Te
        share_percent: 0.4
        share_high: 0.7
        role: The free-cutting additive. Wikipedia says copper telluride (weissite) precipitation increases hardness.
        source: pubchem-tellurium
        where: Element record, molecular weight as printed by PubChem; composition from the datasheet chemical composition table
      - name: Phosphorus
        symbol: P
        share_percent: 0.004
        share_high: 0.012
        role: Deoxidiser. The datasheet notes that deoxidised grades use deoxidisers such as phosphorus, boron or lithium in an amount agreed upon.
        source: concast-c14500
        where: Chemical composition table and note
  risk_groups:
    - title: For people
      lead: The alloy is a solid metal, but machining makes dust that contains tellurium and copper. The element record carries a Danger label.
      level: 2
      verdict: Dust and element hazard
      points:
        - label: Tellurium as an element
          line: The PubChem summary for tellurium, from 527 company reports, lists the signal word Danger, with H332 at 61.3 %, H317 at 45.7 % and H362 at 43.8 %. The alloy holds only 0.40 to 0.70 % tellurium, and no alloy safety data sheet was found.
        - label: Dust limit
          line: NIOSH and OSHA set 0.1 mg/m3 as a time-weighted average for tellurium, as Te. The IDLH is 25 mg/m3 as Te.
        - label: Copper
          line: The PubChem copper summary lists H400 at 43.1 % and H410 at 18.8 %, which means very toxic to aquatic life.
    - title: If it fails
      lead: These are failure routes found in the sources. The datasheet gives no fatigue or creep data for this grade.
      points:
        - label: Overheating the temper
          line: The datasheet prints an annealing range of 800 to 1200 °F. Heating into that range removes the cold work behind the H02 and H04 strengths, and the datasheet gives no annealed strength for C14500.
        - label: Welded joints
          line: The datasheet rates spot, seam and coated-metal arc welding not recommended. Wikipedia says the alloy is not suited to welding, though gas shielded arc and resistance welding can be used.
    - title: Handling and storage
      points:
        - label: Dust
          line: Keep tellurium dust below the time-weighted average of 0.1 mg/m3 as Te.
        - label: Heat treatment
          line: The datasheet prints a hot treatment range of 1400 to 1600 °F and an annealing range of 800 to 1200 °F.
  why: Tellurium copper, UNS C14500, is copper with about half a percent of tellurium. The tellurium lets the metal cut much more easily than pure copper, close to the ease of brass, while keeping most of its electrical conductivity and its hot-working behaviour. Wieland Concast gives a density of 8.94 g/cm3, an electrical conductivity of 93 % IACS and a thermal conductivity of 355 W/(m·K) at 20 °C. Its minimum tensile strengths are 260 MPa in the H02 half-hard temper and 330 MPa in H04 hard, which is why it is used for parts that must be machined, soldered and carry current.
  uses:
    - where: Electrical connectors and switch parts
      line: Wieland Concast lists electrical connectors, motor parts, soldering copper, switch parts and transistor bases as typical uses.
    - where: Screw-machine parts and fittings
      line: The same datasheet lists screw machine products, forgings and soldering tips among industrial uses, and plumbing fixtures, fittings and sprinkler heads among plumbing uses.
    - where: Space use
      line: No NASA, ESA or flight source for tellurium copper was found in this run, so no space application is recorded.
  can_do:
    - label: Carry current
      value: 93 % IACS
      benchmark: electrical_conductivity
      line: Electrical conductivity is 93 % IACS at 68 °F, printed in the datasheet alongside 0.539 MS/cm at 20 °C.
    - label: Carry heat
      value: 355 W/(m·K)
      benchmark: thermal_conductivity
      line: Thermal conductivity is 355 W/(m·K) at 20 °C.
    - label: Weight
      value: 8.94 g/cm3
      benchmark: density
      line: Density is 8.94 g/cm3 at 20 °C.
    - label: Melting
      value: 1080 °C liquidus
      benchmark: melting_point
      line: The alloy melts between a solidus of 1051 °C and a liquidus of 1080 °C.
    - label: Strength in H04
      value: 330 MPa
      benchmark: ultimate_tensile_strength
      line: The H04 hard rod has a minimum tensile strength of 330 MPa, 275 MPa yield and 4 % elongation. The H02 half-hard rod has 260 MPa, 205 MPa and 8 %.
    - label: Machinability
      value: '85'
      benchmark: machinability_rating
      line: The datasheet gives a machinability rating of 85, and Wikipedia says the alloy machines at speeds close to brass.
  compare: Wieland Concast says tellurium copper has similar mechanical properties to unalloyed pure copper, with better machinability. Wikipedia says its machinability is close to brass. This profile holds no pure-copper figures from this run, so the comparison is qualitative and the table gives this grade's values only.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Electrical conductivity
      benchmark: electrical_conductivity
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - 'Specify the temper: H02 and H04 have different strengths, and the size range changes the elongation minimum.'
    - Keep tellurium dust below the time-weighted average of 0.1 mg/m3 as Te.
    - Anneal and hot treat only within the printed ranges of 800 to 1200 °F and 1400 to 1600 °F.
    - Do not spot, seam or coated-metal arc weld the alloy, since the datasheet rates those not recommended.
  good_for:
    - 'Free machining with conductivity: a machinability rating of 85 with 93 % IACS electrical conductivity.'
    - Electrical connectors and switch parts, as the datasheet's typical uses.
    - 'Soldering: the datasheet rates soldering excellent.'
  watch_out:
    - 'Tellurium: the element carries a Danger label in the PubChem summary, and the dust limit is 0.1 mg/m3 as Te.'
    - 'Welding: spot, seam and coated-metal arc welding are not recommended.'
    - 'Corrosion: the only statement is a supplier''s claim with no test data, so no corrosion rate is recorded.'
    - 'Supply: China produced 80 % of refined tellurium in 2025 (USGS), and tellurium is on the 2025 U.S. critical minerals list.'
  verdict: Tellurium copper is the free-cutting copper for electrical parts. It gives 93 % IACS conductivity and a machinability rating of 85, in tempers with 260 to 330 MPa tensile strength. Its tellurium brings a dust hazard during machining, the datasheet advises against spot and seam welding, and no quantitative corrosion data were found for this grade.