The effect of precipitates on the superelastic response of [100] oriented FeMnAlNi single crystals under compression

FeMnAlNi shape memory alloys were recently discovered to have a small temperature dependence of the superelastic critical stress in a large superelastic temperature window from -196 degrees C to 240 degrees C. In this work, we investigated the effect of B2 nanoprecipitates on the superelastic characteristics of [100] oriented Fe43.5Mn34Al15Ni7.5 single crystals under compression, and found that the size, volume fraction and composition of precipitates strongly influence the transformation temperature, superelastic strain, critical stress for stress-induced martensitic transformation and stress hysteresis of the single crystals. The single crystals aged at 200 degrees C for 3 h show 7.2% superelastic strain with the precipitate size of about 6-10 nm. Longer aging times or higher aging temperature reduces superelastic recovery due to the coarsening of the precipitates. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.