2005 Volume 46 Issue 5 Pages 983-989
A statistical description of the superelastic behavior of martensitic alloys has been applied to the stress–strain curves obtained for a Cu69.6Al26.8Ni3.6 at% single crystal under compression which shows a mechanical stabilization effect of the stress-induced γ′ martensite. In order to analyse very different stress–strain behaviours, the same model has been applied to a Cu68.3Zn15.4Al16.3 (at%) single crystal showing the β–β′ transformation under tension with almost “ideal” superelasticity.
The model, which reproduces accurately the experimental σ–ε curves, allows to compute the volume fractions of martensite at every stage of the loading–unloading cycle by introducing a probability distribution function or, if the elastic stiffness coefficients are known, by performing some calculations directly from the experimental stress–strain loops.
The mechanical stabilization of γ′ martensite in the Cu–Al–Ni alloy is manifested through the large differences in the probability distributions between the forward and reverse transformations. The dependence of the mechanical stabilization degree on the amount of previous deformation is also quite well reproduced by the model.