Work performance in TiNi alloy during heat cycling in the temperature range of $B2\leftrightarrow R$ martensitic transformation

The possibility of useful work performance in a TiNi alloy during heat cycling in the temperature range of the $B2\leftrightarrow R$ martensitic transformation has been studied. In the regime of work performance during heat cycling, the alloy sample was cooled under a constant applied stress of 0, 50, 100, or 150 MPa, while heating was performed under a constant stress of 200 MPa. The results show that a TiNi alloy is capable of performing useful work during heat cycling in the temperature range of $B2\leftrightarrow R$ transformation. A maximum work output of 0.45 MJ/m$^3$ was observed in the case of cooling at an applied stress of 100MPa. The efficiency of work performance in this case amounted to 1.3%, which was about half of the value for heat cycling in the temperature range of the $B2\leftrightarrow B19'$ martensitic transformation.