Enhancing the activity of 〈c + a〉 dislocations in Mg alloys via high-energy pulsed current

The activation of non-basal slip systems, especially 〈c + a〉 dislocations, is crucial for enhancing plasticity of magnesium alloys at room temperature. Based on the concept of current induced local Joule heating along grain boundaries, we examined the effect of pulsed currents on enhancing the uniform elongation of strongly textured AZ31 magnesium alloys at near room temperature. The samples were subjected to uniaxial tension along the RD direction at near room temperature while a continuous current or wide-frequency pulsed current was applied, with careful control of the current parameters to avoid excessively high temperature rises. Using electron backscatter diffraction and two-beam transmission electron microscopy characterization, the textures and dislocations with/without applied pulsed current were analyzed. The uniform elongation is increased while the texture is weakened under pulsed current compared with under constant temperature or continuous current. Combined with numerical simulations, we propose that the enhanced activation of 〈c + a〉 dislocations by pulsed currents provides plastic deformation and weakens the texture. This is attributed to the local high temperature generated by low-frequency pulsed currents near defects. These findings provide new insights into controlling the plastic deformation mode of hexagonal metals under near-room temperature conditions, which could have significant implications for the widespread application of such lightweight materials in critical areas.