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通过改变凝固过程中的冷却速率,研究了冷却速率对Mg-Gd-Y-Zr合金凝固组织与成分微观偏析的影响。随冷却速率提高,合金组织明显细化,初生相形貌由粗大等轴枝晶逐渐向细小树枝晶转变,合金凝固过程中形核率增加,合金晶粒尺寸逐渐减小;冷却速率的提高可以降低溶质元素的扩散速率,从而增加合金元素在枝晶干中的固溶度,减轻凝固过程中合金元素Gd与Y的微观偏析,同时使凝固过程中形成的共晶减少,共晶组织分布更加弥散、均匀。
By changing the cooling rate in the process of solidification, the effect of cooling rate on the microsegregation of the microstructure and composition of Mg-Gd-Y-Zr alloy was studied. With the increase of cooling rate, the microstructure of the alloy is obviously refined. The morphology of the primary phase changes from coarse equiaxed dendrite to fine dendrite. The nucleation rate increases and the grain size of the alloy decreases gradually. The cooling rate can be increased Reduce the diffusion rate of solute elements, increase the solid solubility of alloying elements in the dendrites, mitigate the microsegregation of alloying elements Gd and Y in the solidification process, decrease the eutectic formation during the solidification process, and further increase the eutectic distribution Diffuse, uniform.