Cu-Cr合金初始凝固界面形态对组织形成的影响

Effect of interface morphology on microstructure during non-steady directional solidification of Cu-Cr alloy

依据定向凝固初始过渡区的溶质分布,探讨了Cu-1.0wt%Cr合金凝固界面形态对组织形成的影响。研究表明:亚共晶Cu-1.0wt%Cr合金初始非稳态定向凝固过程经历了平面状初生α相、完全(α+β)共晶组织以及枝晶状α相和共晶的混合组织的三个演变阶段。随着凝固速度的增加,初始过渡区内单相α的凝固长度减小;初始凝固平界面易在初始过渡区的单相α生长阶段发生失稳,并导致完全(α+β)共晶组织的凝固过程不会发生。理论分析得到的初始过渡区平界面失稳及组织演变的规律,与实验结果相吻合。

Based on the liquid solute distribution in an initial transient zone during non-steady directional solidification, the effect of interface morphology on microstructure of Cu-1.0wt% Cr alloy was investigated. It is found that the microstructure in an initial transient zone undergoes α series of changes from the planar single α phase, the complete eutectic （α ＋ β） to the compound of dendrite α phase and eutectie （α ＋β） . With increase of solidification rates, the length of the planar single α phase in an initial transient zone shortens, and the planar interface instability can easily take place in the single α phase zone so that the complete eutectic （α ＋β） eann＇t come into being. The evolution of microstrueture during directional solidification of Cu-Cr alloy based on the theoretical analysis are consistent with the experiment results.