Microstructure evolution of AM60 magnesium alloy semisolid slurry prepared by new SIMA

摘要

AM60 magnesium alloy semisolid slurry was prepared by new strain induced melt activated (new SIMA) and its microstructure was observed under optical microscope and then analyzed via digital image anal-ysis system. The results showed that microstructure was well refined to many fine equiaxed grains with the average size of 8 pm after the process of as-cast AM60 magnesium alloy by equal channel angular extrusion (ECAE). And fine and spheroidal semisolid slurry with average grain size ranging from 9.9 pm to 17.3 um was prepared by new SIMA and the used time was also shorter, as compared with semisolid isothermal treatment (SSIT). LSW theory of Ostwald ripening was demonstrated to be able to be used for the description of the coarsening process of semisolid slurry in new SIMA, instead of coalescence of solid grains in SSIT. When the isothermal temperature was increased, primary solid grains showed an initial increase and a following decrease of an average grain size.