Elastic limit of Fe-Pd alloys exhibiting lattice softening

Abstract

The elastic limit (maximum elastic strain) of Fe.Pd alloys exhibiting a second-order-like martensitic transformation from the face centered cubic structure to the face centered tetragonal structure was investigated by varying the test conditions. The elastic limit decreased from 7.3% to 4.6% as temperature was increased from 240 K to 300 K, a phenomenon that can probably be attributed to the strong temperature dependence of the elastic constant CŒ. The elastic limit also significantly decreased upon changing the compression direction from [001] to [011] because of the large elastic anisotropy. However, the critical resolved shear stress was only slightly influenced by temperature and the compression direction. The elastic limit of a polycrystalline specimen of the alloy was one order in magnitude smaller than that of its corresponding single crystal. © 2014 ISIJ.