Influence of maximum thermal cycle temperature on the two-way shape memory effect in TiNi Alloy

Abstract The influence of the maximum thermal cycle temperature on the value and temperatures of the two-way shape memory effect (TWSME) was studied in Ti 50 Ni 50 alloy subjected to a preliminary deformation by two ways: through isothermal deformation up to 12% in the martensite state, or via cooling and heating under a constant stress of 80 MPa. Additionally, the samples were subjected to one or 10 thermal cycles within the temperature range of 440–300 K to change the dislocation structure formed during preliminary deformation. It was found that values of the TWSME and martensitic transformation temperatures varied in three temperature ranges on an increase in maximum thermal cycle temperature. In the first temperature range from 440–490 K, a variation in TWSME parameters was observed in the samples that were not subjected to a preliminary 10 thermal cycles. In the second temperature range from 490–640 K, a redistribution of the dislocations resulted in a decrease in the value of TWSME at a low rate, and hardly increased the M s temperature. In the third temperature range from 640–700 K, a recrystallization led to a significant decrease in the value of TWSME and a strong increase in M s temperature.