Microstructural evolution during semisolid state strain induced melt activation process of aluminum 7075 alloy
(1. Department of Mechanical Engineering, Eastern Mediterranean University, Mersin 10, Turkey;
2. School of Material Engineering and Metallurgy, Iran University of Science and Technology, Tehran, 16844, Iran)
2. School of Material Engineering and Metallurgy, Iran University of Science and Technology, Tehran, 16844, Iran)
Abstract: The effects of compression ratio on the microstructure evolution of semisolid 7075 Al alloy produced by the strain induced melt activation (SIMA) process were investigated. The samples were cold deformed by compression into the different heights up to 40% reduction. The isothermal holding treatments were carried out at 625 °C for predetermined time intervals. The results reveal that the average grain size is gradually reduced with the increase of the compression ratio. When the compression ratio surpasses 30%, the above descending trend is not as evident as that below 30% reduction. During the subsequent heat treatments, the recrystallization is induced in the deformed samples by the increasingly accumulated strain energy. The grain growth mechanisms and the microstructural coarsening of the SIMA processed 7075 Al alloy were discussed and confirmed.
Key words: thixoforming; thermomechanical processing; aluminium alloys; semi-solid metal