The contribution of order to the phase stability of β-Cu-Zn-Al.

We report the lower stability temperatures, T-beta, of the body centred cubic (bcc) beta phase for several alloys along the line of compositions Cu0.76-0.5x-Zn-x-Al0.24-0.5x, corresponding to a constant electron to atom ratio e/a = 1.48. The results have been obtained by means of differential scanning calorimetry measurements at various heating rates. The influence of atomic ordering on the stability of the bcc structure was evaluated using a mixed approach involving Monte Carlo simulations and the cluster variation method. It was found that the chemical short- and long-range ordering contributes to the free energy of the alloy by an amount of around 200k(B).