Investigation of electrical pulse induced retrogression and restoration effect of Al-Mg-Si alloy

The retrogression and restoration effect of Al-Mg-Si alloy induced by transient electrical pulse were discovered and investigated. It was found that electrical pulse could cause the retrogression of material strength for naturally aged Al-Mg-Si alloy. Further experiments indicate that an electrical pulse with a higher current density can cause more significant retrogression effect. The retrogression of material strength is caused by the dissolution of metastable Mg-Si co-clusters when electrical current pulse passing through the material. It was also found that the material strength could restore at room temperature because of the precipitation of rod-shaped β' phase. This research reveals that transient electrical pulse not only influence the metastable precipitates in Al-Mg-Si alloy, but also affect its subsequent precipitation. It provides a new understanding about the effect of electrical current on the mechanical properties and microstructures of aluminum alloy.