脉冲磁致振荡下Al-4.5wt%Cu合金微观组织形态

MORPHOLOGY OF THE Al-4.5wt%Cu ALLOY BY PULSE MAGNETO OSCILLATION TREATMENT

应用脉冲磁致振荡技术处理Al-4.5wt%Cu合金的凝固过程,并用快速凝固装置固化初生α-Al相。结果表明,合金凝固前期,熔体固相分数小,温度高,脉冲磁致振荡主要促进熔体形核,此刻初生α-Al相微观形貌细小,圆整。随着处理时间的延长,熔体温度降低,脉冲磁致振荡难以抑制晶核的快速生长,新、老晶核竞相生长,并发生吞并或融合,晶粒粗大,形状复杂。一定放电频率的脉冲磁致振荡处理能有效抑制初生α-Al相的长大,频率越高,抑制效果越好,且初生α-Al相随着放电频率的增高变得更加细小、圆整。

The pulse magneto oscillation（PMO） technique was applied to the solidification process of Al-4.5wt%Cu alloy,and the microstructure morphology of primary α-Al phase was solidified with a rapid solidification setup. The results showed that during early stage of alloy solidification,the solid fraction of melt was small and the temperature was high,PMO mainly promoted the nucleation of melts; the microstructure morphology of primary α-Al phase was fine and round; with the increasing of treatment time,the temperature of melts decreased,and PMO could not inhibit the fast growth of crystal nucleus. Therefore,new crystal nucleus competed with primary ones during growing and combination and merging occurred,thus resulting in the formation of coarse and complicated-shaped grains. PMO treatment with certain discharging frequency could effectively inhibit the growth of primary α-Al phase,with the increasing of frequency,it could obtain better inhibition effects and the primary α-Al phase tended to be finer and rounder.