Tellurium copper

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Tellurium copper is an alloy of copper and tellurium. Tellurium improves machinability of copper.


Tellurium is usually added to copper to improve machinability ("free cutting"). ASTM specification B301 has 0.5% tellurium; at concentrations of up to 0.75% machinability is improved whilst electrical conductivity and hot working behavior is maintained. Mechanical properties are similar to tough pitch copper, whilst machinability is similar to brass - the alloy's hardnesses are increased by precipitation of copper telluride.[1]

Tellurium copper is not suited to welding though can be welded with gas shielded arc welding or resistance welding; it can be readily soft soldered, silver soldered, or brazed.[2]

Tellurium copper can be used as the electrode in electrical discharge machining (EDM) - the alloy is used to replace copper when grinding wheel loading occurs during fine finishing of the electrode - the alloy retains the properties of copper in the EDM process.[3]

Phase diagram[edit]

Copper forms tellurides. These include Cu4Te, Cu2Te (m.p. 1125C), and CuTe. A eutectic forms at 71% (mol) Te, (m.p. 340C). Between 4.3 to 30% (mol) Te there is stratification between Cu and Cu2Te.[4]


  1. ^ "Usage Patterns for Tellurium", A Report of the NMAB (National Materials Advisory Board) (Report), National Research Council (NMAB-257), p. 10, Aug 1969
  2. ^ Warne, D.F., ed. (2000), Newnes Electrical Engineer's Handbook, 3.4.11 Copper and its alloys, p.52, ISBN 0750648791
  3. ^ Rao, P.N., ed. (2009), "11. Unconventional Machining Processes", Manufacturing Technology, 2 Metal and Machine Tools (2nd ed.), Tata McGraw-Hill (New Delhi), § 11.2.5 Electrodes, p.305, ISBN 0070087695
  4. ^ Borisova, Z. (1981), Glassy Semiconductors, Springer, 7. The Arsenic-Tellurium-Copper System, p.423, doi:10.1007/978-1-4757-0851-6

Further reading[edit]

  • Pashinkin, A.S.; Federov, V.A. (June 2003). "Phase equilibria in the Cu–Te system". Inorganic Materials. 39 (6): 539–554. doi:10.1023/A:1024003932461.
  • Blachnik, R.; Lasocka, M.; Walbrecht, U. (15 July 1983). "The system copper-tellurium". Journal of Solid State Chemistry. 48 (3): 431–438. doi:10.1016/0022-4596(83)90102-0.

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