Large elastic-like strain in an Fe-31.2Pd (at.%) alloy exhibiting a second-order-like FCC-FCT martensitic transformation

Abstract

Fe-Pd alloys containing Pd content of approximately 30at.% exhibit a second-order-like FCC-FCT martensitic transformation and the elastic constant C′ of the Fe-Pd alloys softens on approaching the transformation temperature. We examined the deformation behavior of an Fe-31.2Pd (at.%) alloy by making compressive tests in the [001] direction. It was found that the stress-strain curve significantly depends on test temperature. In addition, a large reversible strain of 6.5% with quite small stress hysteresis was obtained at 240 K under stress of 250 MPa. The yield point appeared at 285 MPa where the strain is 7.3%, and residual strain appeared after the yielding. The main reason for the residual strain is the introduction of {111} mechanical twinning. A significant elastocaloric effect was also observed by the application and removal of stress in the [001] direction.