高压凝固对Al-Mg合金枝晶形态的影响

Effects of High Pressure Solidification on Dendritic Morphology of Al-Mg Alloy

利用OLYMPUS光学显微镜研究了高压凝固对Al-9·6Mg合金枝晶形态的影响。结果表明,与常压下典型的破碎的粗大枝晶组织相比,高压凝固条件下,枝晶臂较完整,二次枝晶间距减小,并且大部分一次枝晶臂增长。从高压对成分过冷和热过冷的影响及溶质扩散角度探讨了枝晶形态的变化机理。高压这种极端凝固条件为改变合金的组织形态提供了一种新途径。

Effects of high pressure solidification on dendritic morphology of Al-9.6Mg alloy have been described by Olympus optical microscope. The results demonstrate that while the microstructural dendritic is coarse and broken under normal pressure, dendritic arm keeps completeness in which secondary dendritic arm spacing is decreased and major primary dendritic arm is grown under high pressure. Evolution mechanism of dendritic morphology has been expounded from the viewpoint of effects of high pressure on constitutional undercooling and heat undercooling as well as solute diffusion. High pressure solidification, as an extreme solidification condition, can provide a new approach to change the structural morphology in the alloy.