Effects of thermo-mechanical training on a Fe59Mn30Si6Cr5 shape memory alloy

The effects of thermo-mechanical training on a Fe59Mn30Si6Cr5 (numbers indicate wt.%) shape memory alloy are studied in this study. The thermo-mechanical training is carried out by controlling the training parameters of applied strain, annealing temperature and cyclic number. Experimental results show that the thermo-mechanical training can raise the stacking fault probability and reduce the critical stress of inducing ɛ martensite. Therefore, the ɛ martensite is easily stress induced from the γ matrix. The cyclic hardening phenomenon occurs at low annealing temperature due to the accumulation of Shockley partial dislocations and stacking faults introduced during the training cycles. Meanwhile, the cyclic hardening phenomenon is more significant at higher tensile strain. At higher annealing temperature, the cyclic hardening effect can be reduced by eliminating the density of the dislocations and the ɛ martensite can be recovered to the γ phase completely during the reverse transformation process. These features will improve the shape memory ability of Fe59Mn30Si6Cr5 alloy.