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综合采用熔融玻璃净化、铜模喷铸及单辊旋淬技术,对比研究不同过冷度、不同冷速作用下Cu-Co不混溶合金的快速凝固行为。通过对凝固发生时的热流方式、形核及生长过程的分析,阐述合金非平衡组织由枝晶到分相结构的转变及其相应尺寸的变化规律。随过冷度增加,不混溶效应的增强导致柱状枝晶向分相结构转变。由于铜模喷铸时发生多点形核,凝固组织呈现为等轴枝晶并随冷速增加而不断细化。当喷铸试棒直径为4 mm时,不混溶效应形成的液滴由于长大不充分最终形成细小粒状分相组织。单辊旋淬薄带由于冷速最高,凝固过程瞬间完成,可有效抑制液相分离的发生,有利于胞状单相固溶体组织的形成。
The rapid solidification behavior of Cu-Co immiscible alloy under different supercooling and different cooling rates was studied by the combination of molten glass purification, copper mold casting and single-roller rotary quenching. Through the analysis of the heat flow, nucleation and growth process during the solidification, the transformation of the non-equilibrium structure of the alloy from dendrite to the phase-separated structure and the variation of its corresponding size were described. With the increase of undercooling, the enhancement of immiscibility leads to the transformation of columnar dendrites to the phase separation structure. Due to the multi-point nucleation occurred during the casting of copper mold, the solidified structure showed equiaxed dendrite and refined with the increase of cooling rate. When the diameter of spray test bar is 4 mm, the droplets formed by the immiscibility effect will eventually form fine granular phase-separated microstructure due to insufficient growth. Due to the highest cooling speed, the solidification process is completed instantaneously, which can effectively suppress the occurrence of liquid phase separation and is favorable for the formation of single-phase solid solution.