SOME ASPECTS OF THE 2 WAY SHAPE MEMORY EFFECT INDUCED BY PSEUDOELASTIC CYCLING IN CU-ZN-AL ALLOYS

The two-way shape memory effect (TWSME) induced by pseudoelastic cycling in Cu-Zn-Al single crystals has been studied. We analyzed the influence of the mechanical cycling characteristics (tensile or compressing) and of the presence of gamma-phase precipitates in the material. The two-way memory effect induced by compressing cycling appears after a smaller number of cycles than in tensile pseudoelastic cycling. The presence of gamma-phase precipitates also reduces the number of cycles needed to get the TWSME. Samples with TWSME are able to overcome some external stress when going to the martensitic shape until a threshold stress, sigma(th), value is reached. When higher opposing stresses are applied, the degradation of TWSME starts.