The microstructure and mechanical properties of nanocrystalline Mg-Zn-Y alloy achieved by a combination of aging and high pressure torsion

摘要

The microstructure and mechanical properties were systematically investigated through a research of high pressure torsion (HPT) processing of solution and age-treated Mg-Zn-Y alloy. The results showed that the coarse W (Mg3Y2Zn3) eutectic phase was fragmented into finer particles during HPT and the amount of nano-sized MgZn and MgZn2 precipitates induced by age treatment were significantly reduced with the increase of torsional turns, which indicates that a larger amount of precipitates were dissolved into the alpha-Mg matrix. In addition, we observed the segregation of Zn atoms to the grain boundaries under HPT deformation at ambient temperature in an age-treated Mg-Zn-Y alloy. Meanwhile, nanocrystalline materials with grain size of 53 nm were successfully prepared after HPT for 7 turns, which is almost the smallest ever published for a Mg-Zn-Y alloy. The present age-treated Mg-Zn-Y alloy showed very different hardening behaviour and microstructure evolution after HPT deformation.