Thermomechanical training behavior and its dynamic mechanical analysis in an Fe-Mn-Si shape memory alloy

By using a deformation-recovery test and dynamic mechanical analysis, the effects of thermomechanical training on martensitic transformation and shape memory effect have been studied in an Fe-33.7Mn-5.22Si alloy. Experimental results show that the volume of thermal martensite is small. The volume of reversible martensite (VRM)-that is, the martensite formed by stress-inducing, which can reverse transform into austenite upon heating-increased more than ten times the amount of thermal martensite by stress-inducing upon heating. The recovery temperature was found to have a crucial effect on the volume of martensite. For thermomechanical training with low recovery temperatures, VRM decreases after the third cycle. Thermomechanical training at recovery temperatures of 500 degrees C and 600 degrees C increased the VRM by more than 1.8 times the volume of stress-inducing martensite before training, with almost complete shape recovery. The shape recovery ratio of the alloy was found to be proportional to the VRM. This was determined by integrating the internal friction peaks with respect to temperature in the reverse martensitic transformation. (C) Elsevier Science Inc., 1996.