Efficiency and work performance of TiNi alloy undergoing B2 ↔ R martensitic transformation

Abstract

Abstract This study is devoted to the investigation of the ability of Ti48Ni52 alloys for production of effective work during thermal cycling over a narrow temperature range. Effective work output and efficiency were studied in Ti48Ni52 alloy subjected to thermal cycling through the temperature range of the B2 ↔ R martensitic transformation under different stress regimes. The optimal stress regimes for production of effective work output and maximum efficiency were found. The data obtained have shown that under optimal stress conditions (cooling of the sample under a stress of 100 MPa and heating under a stress of 400 MPa), one may develop a device with effective work being equal to 1.5 MJ m−3 and an efficiency of 2.5 %. During repeated thermal cycling under the optimal stress regime the alloy accumulated 8 % irreversible strain per 30 cycles. Starting from the 20th cycle the rate of irreversible strain accumulation was equal to ∼ 0.06 % per cycle.