Order-disorder in binary substitutional alloys: a simple Ising approach

Abstract

To gain insight to the nature of the order-disorder transformation in alloys, the Ising model with nearest-neighbour interactions is frequently used. The three-dimensional Ising model cannot be solved exactly, but modern approximation methods yield results which do not differ widely from exact solutions. Their mathematical derivations are complicated according to the fascinating physical features of the critical point. However, in the present study it could be shown that the Ising order-disorder temperatures of the simple cubic and b.c.c. lattices can be derived with sufficient accuracy from a simple graphical interpolation method. The specific heat vs. temperature curves are calculated. They show second-order transitions with rather high values of remaining short-range order at temperatures above the critical temperature.