Rheo-Forming AZ91D Magnesium Alloy Using Enthalpy Equilibrium Electromagnetic-Stirring Process

摘要

An enthalpy equilibrium electromagnetic-stirring process was introduced to semisolid metal processing for rheoforming route. AZ91D was die-casted under normally liquid state of Mg alloy, semisolid state of Mg alloy stirred using traditional EM-stirrer and an enthalpy equilibrium EM-Stirrer, respectively. Further step, effect of pouring temperature on microstructures and tensile properties of castings was researched in the introduced process. Experimental results indicated that samples of rheo-diecasted in the introduced process showed globular primary solid particle microstructure and better comprehensive mechanical properties, typical microstructures consisting of globular primary a-Mg grains and pseudoeutectic organization was observed in the castings with low solid fraction, while in higher solid fraction, the microstructure comprised of agglomerating primary solid particles and Mg_(17)Al_(12) of divorced eutectic. With decreasing pouring temperature, the density of primary solid particles increased greatly, the size of primary solid particle evolved to coarse.