Intermetallic compounds are solid phases containing two or more metallic elements, with optionally one or more non-metallic elements, whose crystal structure differs from that of the other constituents. Under this definition the following are included
- Electron (or Hume-Rothery) compounds
- Size packing phases. e.g. Laves phases, Frank–Kasper phases and Nowotny phases
- Zintl phases
The definition of a metal is taken to include:
- the so-called post-transition metals, i.e. aluminium, gallium, indium, thallium, tin and lead
- some, if not all, of the metalloids, e.g. silicon, germanium, arsenic, antimony and tellurium.