Laser Powder Bed Fusion of Fe–Mn–Si based shape memory alloys with high performance at room and cryogenic temperature

Abstract

A Fe–Mn–Si based alloy with high shape memory effect (SME) and mechanical performance at both cryogenic and room temperature was fabricated by laser powder bed fusion (LPBF) with blended elemental powders. The effect of laser power on the elemental uniformity, microstructure, SME, strength of the as-built sample was investigated. The developed alloy shown superior SME under high laser power, due to the fully transformation of initial bcc phase to the stable fcc phase during the cooling process. The developed Fe–Mn–Si alloy shown high shape recovery rate of 63 % and 92 % after ∼0.05 bending strain at room and cryogenic temperature, respectively. The as-built samples had characteristic microstructure of small fcc phase grains and high density of stacking faut and twins. The as-built sample exhibited room/cryogenic tensile strength as high as 962MPa/1372 MPa, respectively, with considerable plasticity. This work provides foundations for fast development of high performance additively manufactured shape memory alloy (SMA).