Enhanced phase transformation and variant selection by electric current pulses in a Cu–Zn alloy

The variant selection from the parent α phase to the product β phase during the enhanced phase transformation induced by the electric current pulses (ECPs) was investigated in a Cu–Zn alloy. The electron backscatter diffraction results showed that the crystallographic variant selection was not only across those prior α/α grain boundaries, but also within the α grain interior, and it implied that the nucleation of the β phase on the up-transformation obeyed a preferred orientation selection. Further analysis revealed that the orientation relationship between the α phase and the β phase variants nucleated from the α phase was close to 44.3° about <114>, which clearly described the rotation axes and the misorientation angles in terms of an axis/angle description when the high temperature phase nucleated from the matrix. Therefore, the ECP treatment would provide a new promising and convenient method to investigate the variant evolution on the up-transformation.