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

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.