Larger Recovery Strains in Cast Fe–Mn–Si‐Based Shape Memory Alloys by Reducing Thermal Activation and Optimizing Mn Content

Abstract

Previous work showed that a maximal recovery strain of 8.4% after being bent at room temperature was realized in annealed cast polycrystalline Fe‐Mn‐Si‐based alloys because of the reduced annealing twin boundaries. Theoretically, higher recovery strains can be expected at cryogenic deformation by reducing thermal activation. To confirm this idea, martensitic transformation behaviors and the recovery strains after being bent at 77 K were investigated in the cast Fe‐(20‐26)Mn‐5.5Si‐8.5Cr‐5Ni alloys. We realized larger recovery strains as high as ∽10.0% in an annealed cast Fe‐23Mn‐5.5Si‐8.5Cr‐5Ni alloy after being bent at 77 K. The reduced thermal activation together with suppressed formation of thermal‐induced martensite by optimizing Mn content can account for the larger recovery strain. These results open up a new avenue for further enhancing the recovery strain in Fe‐Mn‐Si‐based shape memory alloys.This article is protected by copyright. All rights reserved.