Microstructural evolution of AZ61 magnesium alloy predeformed by ECAE during semisolid isothermal treatment

The microstructural evolution of AZ61 magnesium alloy predeformed by equal channel angular extrusion (ECAE) during semisolid isothermal treatment (SSIT) was investigated by means of optical metalloscopy and image analysis equipment. The process involved application of ECAE to as-cast alloy at 310 °C to induce strain prior to heating in the semisolid region for different time lengths. The results show that extrusion pass, isothermal temperature and processing route have an influence on microstructural evolution of predeformed AZ61 magnesium alloy during SSIT. With the increase of extrusion pass, the solid particle size is reduced gradually. When isothermal temperature increases from 530 °C to 560 °C, the average particle size increases from 22 μm to 35 μm. When isothermal temperature is 575 °C, the average particle size decreases. The particle size of microstructure of AZ61 magnesium alloy predeformed by ECAE at BC during SSIT is the finest.