THEORY OF THE HEATS OF FORMATION OF TRANSITION-METAL ALLOYS

A simple expression for the heat of formation ΔH of transition-metal alloys is derived with-in the tight-binding approximation that has the form ΔH=f(N̄)ΔN2, where N̄ and ΔN are the average and difference in number of valence d electrons, respectively. The prefactor f(N̄) is most negative for N̄ 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 ΔH. © 1979 The American Physical Society.