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

Abstract

The stacking-fault energy (γ sf ) of iron-based shape-memory alloys was calculated by the extended dislocation-node method. The results show that Ni and Mn increase the γ 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 γ sf of the alloys is established. Moreover, in terms of the γ sf values of the alloys and the Schaeffler diagram, the alloy design of iron-based shape-memory alloys is carried out. It is found that the alloy having the lowest γ sf has the best shape-memory effect (SME), with a martensite transition temperature (M s ) being a little lower than ambient temperature. The corresponding composition of the alloy is located in the γ-phase zone near the phase line between the γ and γ+e phase zone and the triple point of α+γ+e in the Schaeffler diagram.