In recent years examples of unprecedented functional and structural fatigue resistance and lowered hysteresis in shape memory alloys have been achieved by combining conditions of supercompatibility between phases with suitable grain size and a favorable array of fine precipitates. We collect, review and compare these examples to elucidate the relative roles of these factors, especially in the case of the more demanding stress-induced phase transformations, and we pose key open questions. The control of these factors lends itself to systematic alloy development. Taken together, these results point to significant opportunities to discover improved shape memory alloys as well has new reversible transforming multiferroics.
Bibliographical noteFunding Information:
The work from the University of Minnesota was supported by AFOSR ( FA9550-15-1-0207 ), NSF ( DMREF-1629026 ), ONR ( N00014-14-1-0714 ) and the MURI program ( FA9550-12-1-0458 , FA9550-16-1-0566 ). The work at the University of Kiel was supported by the Deutsche Forschungsgemeinschaft (DFG) via the Priority Program 1599 and the Reinhart Koselleck Project QU 146/23-1. The authors acknowledge fruitful discussions with Jake Steiner and Manfred Wuttig (University of Maryland), with Torben Dankwort and Lorenz Kienle (University of Kiel) and technical support by Rodrigo Lima de Miranda (Acquandas GmbH Kiel). HG and RDJ are pleased to acknowledge the support of Medtronic Corp, via a gift to the University of Minnesota.