SIMA法制备AZ91D镁合金非枝晶组织锭料

Fabrication of magnesium alloy AZ91D ingot with non-dendrites structure using SIMA

研究了利用应变诱发熔体激活法SIMA(Strain InducedMeltActivation)制备AZ91D镁合金半固态非枝晶时的组织转变过程.实验结果表明:具有树枝晶形态的AZ91D合金经20%及30%的预变形后,在半固态升温(540～580℃)或保温(570℃)过程中,其组织形貌由粗化的等轴晶及短树枝晶依次转变为小块状细晶粒→团块状→球状大晶粒.另外,在等温热处理过程中,试样内部体系寻求能量最低状态也是组织转变的一个不可忽略的因素.与未预变形的合金制备的非枝晶组织相比较,经预变形处理的试样是较好的半固态成型材料.

The structural evolution of semisolid AZ91D alloy with nondendrites produced by using the method of StrainInduced Melt Activation (SIMA) is studied. The results indicate that, after AZ91D alloy with dendrites experienced 20% and 30% prior compressive deformation, its microstructure changes in turn from coarse equiaxed grains with short dendrites, into small lumpish fine grains, agglomerate grains, and big spherical grains during the process of isothermal heattreatment at semisolid temperature between 540℃ and 580℃. In addition, it should not be neglected that the system in the sample seeks for the lowest energy condition during the semisolid isothermal heattreatment. The SIMA AZ91D alloy fits well to the requirement of semisolid forming compared with the original AZ91D alloy.