Influence on Microstructure and Mechanical Properties of TiNi Alloy producing by Cold rolling

Abstract:

The effect of rolling at room temperature on the microstructure evolution and mechanical properties of TiNi alloy was investigated by optical microscopy (OM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and transmission electron microcopy (TEM) technique. The results indicate that the B2 austenite phase to B19" martensite phase transformation has occurred in the TiNi alloy; when the deformation is intensified, the non-uniform deformation of microstructure increases, and nanocrystalline and amorphous phases appear. Cold-rolling TiNi alloy exhibits only the elastic deformation and plastic deformation stages of the austenite and martensite phases during the stretching process, and the stress-induced martensite phase-transformation disappears, showing a continuous yielding process. The TiNi alloy have different deformation mechanism at different deformation mechanism: when the strain is 0<ε≤0.3, the main deformation mechanism of the alloy is dislocation slip; When the strain ε>0.3, the deformation mechanism is the combination of twinning and dislocation slip.

Key words:TiNi alloy; cold rolling; martensite transformation; deformation mechanism