Formation of Nanotwins in Cold-Rolled Cu-Zn Alloy by Electric Current Pulses

Abstract

A significant number of nanotwins was fabricated in a cold-rolled Cu-Zn alloy after an electric current pulse (ECP) treatment in this study. Results showed that the formation of nanotwins was related not only to the to phase transformation, but also to the effect of the enhanced directional nucleation along the current direction during the heating caused by the ECP treatment. A theoretical analysis revealed that the nucleation rate of the higher conductivity phase ( phase) was significantly accelerated by the application of an electric current, which provided more nucleation places for the phase during the subsequent rapid cooling process. Especially, during the cooling process, nanotwins with {111} twin planes in the phase would be formed due to the stronger internal stress induced by the rapid cooling rate after the ECP treatment.

Orientation Correlation during α→β Up-Transformation Induced by Electric Current Pulses in a Cu-Zn Alloy

“…Electric current pulses (ECP) is able to heat a small bulk of material to a high temperature in a very short time and then the unstable high temperature states are preserved at ambient temperature by rapidly cooling. [9][10][11][12][13][14][15][16] Obviously, it is possible that after treated by ECP, the unstable β phase formed at the higher temperature in the Cu-Zn alloy may be preserved to the room temperature. Therefore, this technique provides an advanced method to study the variant selection from α to β phase induced by the rapid heating.…”

Magnetic pulse controlled microstructure development in Co49Ni21Ga30 single crystals

“…Recently, Yu et al [37] reported the formation of nano-twins in an FCC structure as the result of the lattice distortion upon the transformation from the B2 to the FCC structure. With a superimposed pulsed MF the formation of nano-twins should become more probable as the generation of a new phase with a higher conductivity should lead to a reduction of the thermodynamic barrier in the conductive system [38].…”

Effect of Electric Current on Microstructural Evolution in a Cold-Rolled 3% Si Steel

“…According to these parameters, the temperature rise caused by ECP can be calculated as about 905°C. 7) In order to prepare samples for texture measurement, the middle affected parts were cut from the samples, and then polished and lightly etched. For each specimen, three incomplete {110}, {200} and {211} pole figures were measured up to a maximal polar angle of 70°by the Schulz back-reflection method using Co-Ka radiation.…”

“…In addition, our previous study also showed that the ð111Þh112i nanotwins in ¡ phase originated from the ¢ phase nuclei and directionally nucleated on the {110} planes in a CuZn alloy treated by electric current pulse (ECP), and it was ascribed to a remarkable anisotropic electric conductivity along the current direction under a high current density. 7) Hence, the preferred nucleation orientation might also have a close relationship with the current direction under ECP treatment, and the influence of electric current direction on recrystallized grain orientation was investigated in this study.…”