The effect of the electric pulse treatment on the microstructure and mechanical performance of the Al-Zn alloy

In this paper, the effect of electric pulse treatment (EPT) on the mechanical performance of the 7075 aluminum (Al) alloy was studied and the correlations between the frequency of the EPT and the microstructure, tensile property and conductivity of the Al alloy were investigated. It is found a noticeable improvement of 6.7% is achieved for the elongation rate at a frequency of 200Hz while the tensile strength changes slightly with the variation of the frequency. Microstructures suggest that the electric pulse tends to change the number and distribution of the second phase precipitations within the grain and form the precipitate free zone around the grain boundary, which enhances the plastic performance of the Al alloy. Also, the treatment facilitates the multiplication of the dislocation tangles and help the alloy maintain a high strength. Conductivity as an important parameter to assess the defect density in the Al alloy initially exhibits a significant increase and then follow a decreasing trend with the increasing frequency. The presented study suggests that the EPT may be a potential effective way to improve the mechanical performance of the lightweight alloy and suits industrial needs.