Effect of ECAP process on liquid distribution of AZ80M alloy during semi-solid isothermal heat treatment

Abstract

Two kinds of semi-solid samples of AZ80−0.2Y−0.15Ca (wt.%) (AZ80M) magnesium alloy were prepared by semi-solid isothermal heat treatment of materials with and without equal channel angular pressing (ECAP) process. The microstructures of initial and semi-solid treated samples were compared and analyzed. The results showed a significant difference in the liquid phase distribution between three-pass ECAP processed (3P) and as-received samples during the isothermal heating process. The semi-solid 3P sample showed a more uniform liquid distribution due to its smaller dihedral angle. Besides, the coarsening processes of solid grains of as-received and 3P samples were dominated by the coalescence and Ostwald ripening mechanism, respectively. The difference of coarsening processes was mainly related to the proportion of the high-angle grain boundaries in materials, which further affected the evolution behavior of the liquid pools.