Theory of the Heats of Formation of Transition-Metal Alloys

Abstract

A simple expression for the heat of formation $\ensuremath{\Delta}H$ of transition-metal alloys is derived with-in the tight-binding approximation that has the form $\ensuremath{\Delta}H=f(\overline{N})\ensuremath{\Delta}{N}^{2}$, where $\overline{N}$ and $\ensuremath{\Delta}N$ are the average and difference in number of valence $d$ electrons, respectively. The prefactor $f(\overline{N})$ is most negative for $\overline{N}$ lying near the middle of the series and it becomes positive towards the edges. The theory gives good agreement with Miedema's semiempirical values of $\ensuremath{\Delta}H$.