Influence of Be addition on order–disorder transformations in β Cu–Al

The dependence of resistivity with temperature around the order–disorder transitions is measured for bcc shape memory alloys Cu–Al (–Be). The experimental curves are discussed in terms of the Rossiter theory, and the parameters involved in this approach are determined. The model allows calculating the variation with temperature of the long-range order degree. Whereas for the binary Cu–Al the kinetics of the order–disorder transformation is first order, the addition of Be leads to a gradual smoothing in the variation of the order parameter below the transition temperature.