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利用扫描电镜(SEM)并配合能谱(EDS)分析研究了超高压凝固Mg-6Zn-3Y合金的晶体形态和相演变.实验结果表明:随着凝固压力的增大,α-Mg晶体的形态发生了粗大树枝晶→超细树枝晶→胞状晶转变,即晶体的生长方式逐渐由树枝晶生长→胞状生长过渡.GPa级超高压下凝固极大地提高了Zn在基体中的溶解度,使之成为过饱和固溶体,并随着凝固压力的增大促使Zn的分布趋于均匀化.Mg-6Zn-3Y合金在2 GPa超高压凝固条件下形成了新相Y固溶体,室温组织由4相组成;在6 GPa超高压凝固条件下大量粒状相均匀弥散地分布在基体上,Mg-6Zn-3Y合金的硬度显著提高.
The crystal morphology and phase evolution of ultrahigh-pressure solidified Mg-6Zn-3Y alloy were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The experimental results show that the morphology of α-Mg crystal increases with the increase of solidification pressure The occurrence of coarse dendrites → superfine dendrites → cellular transitions, that is, the growth of the crystal gradually from the dendrite growth → transitional cell growth.GPa ultra-high pressure coagulation greatly enhance the solubility of Zn in the matrix, making it the Supersaturated solid solution, and the distribution of Zn tends to be uniform with the increase of solidification pressure.Mg-6Zn-3Y alloy forms a new phase Y solid solution under 2 GPa ultrahigh pressure solidification conditions, and the room temperature microstructure consists of 4 phases. 6 GPa under high pressure solidification conditions a large number of granular phase evenly dispersed in the matrix, the hardness of Mg-6Zn-3Y alloy significantly increased.