Research Of Grain Refinement For Mg-Al And Mg-Zn Cast Alloy

As the development of automobile and aerospace fields, magnesium and magnesium alloy is applied more and more wildly. The production is rised to 20% every year in the world. But the key problem of Magnesium application is its poor forming ability.Practice proves that the fine equiaxed crystals structure of magnesium alloy could improve mechanical property. so it is very important to find an effective grain refiner for Magnesium alloys.In this paper, the grain refinement for Mg-Al and Mg-Zn cast alloy is studied by observing their metallurgical structures under as-cast or annealing state. The results demonstrate: the different grain refiners have distinct effect. C,C2Cl6,FeCl3,TiO2 and Ca are the ones that can refine the grains,and refinement effect of C2Cl6 is the best. For pure, Zr,Nd,Ca are better refiners. As the adding amounts of these refiners increase, the grains become smaller. The best is 0.6% for Zr refiner, and the grain is refined from 76μm to 42μm. Nd is refined obviously. The average grain size is 42μm when the Nd content is 1.2%.Added 0.8% Ca and 1.2 Nd has the best refinement effect, which average grain size is 38μm.At the same time, refinement mechanism is studied. In the end mechanics capabilities are tested, and compared with without refined magnesium alloy, It proves plastic and strength characters of magnesium alloy are improved.