Investigation on the two way shape memory effect in a TiNiCu shape memory alloy

The focus of this study is the influence of thermomechanical training in a pure martensite, austensite and martensite+austensite and annealing heat treatment and thermomechanical training on the twoway shape memory effect of TiNiCu alloys. The results showed that when the springs were thermomechanical trained at pure martensite, there is an increase of the recovery rate to a saturated value. The TiNiCu springs were thermomechanical trained at pure austensite and martensite+austensite, there is an increase of the recovery rate to a maximum value and decreased with ongoing training after having passed the maximum value. With increasing annealing temperature, the maximum recovery rate increased first then decreased. Dislocations generated by martensite reorientation were effective in developing twoway memory effect. For the magnitude of thermoinduced or stressinduced martensite variants were different, and the magnitude of the dislocations were different too. Thus, the recovery rate showed different rule with increasing thermomechanical training cycles at different training temperature.