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The influences of thermal cycling treatment in the temperature range of B2-B19 martensitic transformations(-150 to 150 °C) on the Ti Ni alloy structure and properties were studied. Different states named the initial coarse-grained(CG) state, the ultrafine-grained(UFG) state after ECAP(with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% were considered. The results show that the microhardness and the strength increase in all the three states.According to the XRD analysis, a more significant increment in the dislocation density, resulting from thermal cycling, is observed in the UFG alloy than in the CG alloy.
The influences of thermal cycling treatment in the temperature range of B2-B19 martensitic transformations (-150 to 150 ° C) on the Ti Ni alloy structure and properties were studied. Different states named the initial coarse-grained (CG) state, the ultrafine -grained (UFG) state after ECAP (with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% were considered. The results show that the microhardness and the strength increase in all the three states. According to the XRD analysis, a more significant increment in the dislocation density, resulting from thermal cycling, is observed in the UFG alloy than in the CG alloy.