Elinvar property of cold-rolled NiTi alloy

Abstract We tailor the temperature dependence of elastic modulus (TDEM) of polycrystalline NiTi plates by cold rolling up to 60% thickness reduction. In-plane Elinvar property is obtained with a low elastic modulus temperature coefficient of 6.0 × 10−5 K−1 over a temperature range of 192 K. The microstructure mainly consists of approximately equal volume fractions of {111} -oriented B2 and {102} -oriented B19′ nanocrystals of high thermal stability due to defect pinning and grain refinement. The opposite TDEMs of the two phases can compensate each other and cause the Elinvar behavior. Such mechanism can also be used to obtain Elinvar property for other shape memory alloys.