Improvement of the stability of superelasticity and elastocaloric effect of a Ni-rich Ti-Ni alloy by precipitation and grain refinement

In this paper, we report that the superelasticity and the elastocaloric effect of Ti-50.8Ni (at.%) alloy are drastically improved by a combination of precipitation and grain refinement strengthening. The process is as follows: first, aging at 773 K after solution treatment to form coherent fine precipitate of Ti3Ni4; second, cold working followed by annealing at 673 K to form nanocrystalline grain containing Ti3Ni4. The decay of the superelasticity and the elastocaloric effect by 100 stress cycles is <10%. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.