Hume-Rothery phases
Hume-Rothery phases are intermetallic phases that are similar in structure to the various phases of brass . They are named after the British metallurgist William Hume-Rothery (1899–1968). Hume-Rothery phases are important examples of the influence of the valence electron concentration (VEK), the ratio of valence electrons to atoms, on the structure of an alloy. If the valence electron ratio increases, higher lying bands have to be occupied, which makes other structures energetically more favorable.
Brass forms different structures depending on the ratio of copper and zinc . The individual phases are designated with Greek letters (α, β, δ, ε brass).
The structures of Hume-Rothery phases cannot be derived from the ratio of the atoms involved, but only from the VEK. Thus, Cu 3 Al does not crystallize in the structure of ε-brass CuZn 3 , but in that of β-brass, which has a 1: 1 composition of copper and zinc.
literature
- Ulrich Müller: Inorganic Structural Chemistry. Vieweg and Teubner Wiesbaden, 6th edition 2008, ISBN 978-3-8348-0626-0 ( limited preview in Google book search), pp. 237–239.
- Günter Gottstein: Physical basics of materials science. Springer Berlin Heidelberg New York, 3rd edition 2007, ISBN 978-3-540-71104-9 ( limited preview in the Google book search), p. 150.
Individual evidence
- ↑ 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 , pp. 1770-1771.