THE HUME-ROTHERY ELECTRON-CONCENTRATION RULES AND 2ND MOMENT SCALING

We show that the Hume-Rothery electron concentration rules for noble-metal and transition-metal alloys can be understood through simple molecular orbital theory. We consider simple structure types such as the face-centered-cubic, hexagonal-closest-packed, and body-centered-cubic structures as well as more complex structure types such as the sigma-phase, chi-phase, gamma-brass, and beta-Mn structures. Our results are the first theoretical calculations that corroborate the entire set of Hume-Rothery electron concentration rules.