Validating the athermal contribution of electropulsing treatment utilizing T-type Mg specimen

A novel T-type specimen enabled the separation of the thermal and athermal contributions of electropulsing treatment (EPT) in pre-twinned AZ31 Mg alloy. The combination of T-type geometry and carefully selected EPT conditions equalized the thermal contributions at two distinct locations (J70-C and J77-D) in a thermally stable regime, which isolated the athermal effect in J70-C. The results were verified using finite element analysis. Although the athermal EPT contribution did not alter the fundamental microstructural evolution mechanisms, the evolution rate increased significantly. As a result, the J70-C region exhibited faster grain growth, annihilation of twin boundaries, reduction of low-angle grain boundaries, dislocation annihilation, and static recrystallization compared to its counterpart, as further supported by the microhardness trends. These results were interpreted in light of the additional driving force by the athermal EPT contribution, which accelerated the strain-induced boundary migrations beyond Joule heating alone. The proposed T-type specimen methodology offers a robust framework for decoupling the thermal and athermal effects in macroscale EPT processes.