Laves phases

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The Laves phases form one of the largest groups of intermetallic compounds with a defined composition and have the hexagonal C14 or C36 structure or the cubic C15 structure, depending on the metals being joined and the temperature. They are named after the German mineralogist Fritz Laves . They are caused by the optimal packing of spheres of different sizes ( topologically densely packed ). They form alloy-like mixed crystals of the composition MeMe ' 2 with radius ratios around r (Me) / r (Me') = 1.225. For example, the ratio for KNa 2 is 1.25 and for CaMg 2 1.23. Laves phases are usually hard and brittle, but highly heat-resistant. They are not plastically deformable at room temperature. A characteristic property is the almost perfect electrical conductivity corresponding to a purely metallic bond.

literature

  • GER Schulze : Metal Physics. A textbook . Akademie-Verlag, Berlin 1967, (2nd, edited edition. Springer, Vienna et al. 1974).
  • A. von Keitz, G. Sauthoff and P. Neumann: Laves Phases for High-Temperatures - Structure, Stability and Constitution . In: Z. Metallkunde. Vol. 89, No. 12, 1998, pp. 803-810.
  • Armin Von Keitz, Gerhard Sauthoff : Laves phases for high temperatures — Part II: Stability and mechanical properties . In: Intermetallics . tape 10 , no. 5 , 2002, p. 497-510 , doi : 10.1016 / S0966-9795 (02) 00025-0 .
  • F. Stein, M. Palm, G. Sauthoff: Structure and stability of Laves phases. Part I. Critical assessment of factors controlling Laves phase stability . In: Intermetallics . tape 12 , no. 7-9 , 2004, pp. 713-720 , doi : 10.1016 / j.intermet.2004.02.010 .
  • F. Stein, M. Palm, G. Sauthoff: Structure and stability of Laves phases part II — structure type variations in binary and ternary systems . In: Intermetallics . tape 13 , no. 10 , 2005, pp. 1056-1074 , doi : 10.1016 / j.intermet.2004.11.001 .

Web links

Individual evidence

  1. ↑ Zhu, JH; Liu, CT; Pike, LM; Liaw, PK: A thermodynamic interpretation of the size-ratio limits for Laves phase formation . In: Metallurgical and Materials Transactions A . tape 30 , no. 5 , 1999, p. 1449 , doi : 10.1007 / s11661-999-0292-5 .
  2. ↑ Otto-Albrecht Neumüller (Ed.): Römpps Chemie-Lexikon. Volume 3: H-L. 8th revised and expanded edition. Franckh'sche Verlagshandlung, Stuttgart 1983, ISBN 3-440-04513-7 , p. 2330.