Work Production and Variation in Shape Memory Effects during Thermal Cycling of Equiatomic TiNi Alloy

Abstract

The influence of thermal cycling under a symmetric scheme for work performance on the functional properties and work output of equiatomic TiNi shape memory alloys was studied. It was found that the Ti50Ni50 alloy produced an effective work output of 9.7 MJ/m3 and an efficiency of 1.47% in a symmetrical scheme for work production where the stress acting on cooling was 50 MPa, and the stress acting on heating was 200 MPa. It was observed that the Ti50Ni50 alloy demonstrated the monotonic dependence of plastic strain on the number cycle, and 3.1% of the residual strain was accumulated over 30 cycles. The data have shown that using a ‘symmetric’ scheme for work production allows one to reduce a plastic strain 13-fold in comparison with an ‘asymmetric’ scheme. Thus, the symmetric scheme for work production provides for the high stability of the functional properties and work output of TiNi-based shape memory alloys.