Effects of Ti on microstructure and properties of Fe–Mn–Si–Cr–Ni shape memory alloy

Abstract

The effects of Ti on the microstructure and properties of Fe–20Mn–6Si–8Cr–5Ni shape memory alloy prepared by powder metallurgy were investigated. The results showed that trace Ti elements could improve the alloy's compressive yield strength and fracture strength. With the increase of Ti, a precipitated phase gradually appeared in the alloy, which adversely affected the mechanical properties of the alloy. The addition of Ti increased the lattice microstrain of the alloy, which provided the driving force for the martensitic phase transformation and facilitated the shape memory properties of the alloy. There was a relationship between the Ti content and the corrosion resistance of the alloy, with a small amount of Ti producing dispersion strengthening to improve the corrosion resistance of the alloy, and an excess of Ti causing composition segregation to make the alloy susceptible to corrosion. Ultimately, 0.5 wt% Ti was found to have good overall mechanical properties with a compressive yield strength of 1567 MPa and fracture strength of 2140MPa, its superelastic strain was 2.8% and 3.1% (at 10% and 15% pre-strain), respectively.