Alloy design of FeMnSiCrNi shape-memory alloys related to stacking-fault energy

The stacking-fault energy (gamma(sf)) of iron-based shape-memory alloys was calculated by the extended dislocation-node method. The results show that Ni and Mn increase the gamma(sf) of the alloys with an austenite structure, while Cr and Si decrease it. An expression relating the alloying elements of Ni, Cr, Mn, and Si to the gamma(sf) of the alloys is established. Moreov er, in terms of the gamma(sf) values of the alloys and the Schaeffler diagr am, the alloy design of iron-based shape-memory alloys is carried out. It i s found that the alloy having the lowest gamma(sf) has the best shape-memor y effect (SME), with a martensite transition temperature (M-s) being a litt le lower than ambient temperature. The corresponding composition of the all oy is located in the gamma-phase zone near the phase line between the gamma and gamma + epsilon phase zone and the triple point of alpha + gamma + eps ilon in the Schaeffler diagram.