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在变形温度为450°C和应变速率为2 s-1的条件下对均匀化退火后的Mg-7Gd-4Y-1Nd-0.5Zr合金进行热压缩试验。采用金相显微镜(OM)、扫描电镜(SEM)和透射电镜(TEM)综合分析合金变形过程中的动态再结晶机制。采用电子背散射衍射(EBSD)获得晶体微取向信息。结果表明:随应变逐渐增加到-1.88,合金流变应力先快速升高到某个峰值,随后下降到最低值,最后又开始逐渐上升。在低应变下,大量{1 012}拉伸孪晶诱发形核形成动态再结晶晶粒,导致晶粒明显细化。动态再结晶晶粒首先在孪晶边界进行形核,且与孪晶母体存在30°<0001>的取向差。在大应变下,合金组织中在原始大晶粒附近形成细小动态再结晶晶粒,且从原始大晶粒内部到其晶界处的累积微取向连续增加,从而确定合金发生了连续动态再结晶。合金中也发现了粒子激发形核的动态再结晶机制。
The homogenized annealed Mg-7Gd-4Y-1Nd-0.5Zr alloy was subjected to hot compression tests at a deformation temperature of 450 ° C and a strain rate of 2 s-1. The mechanism of dynamic recrystallization in the deformation process of alloy was comprehensively analyzed by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Crystal micro-orientation information was obtained by electron backscatter diffraction (EBSD). The results show that as the strain increases to -1.88, the flow stress of the alloy rapidly increases to a certain peak value first and then decreases to the lowest value, and finally begins to increase gradually. At low strain, a large amount of {1 012} tensile twin induce nucleation to form dynamic recrystallized grains, leading to a significant grain refinement. Dynamic recrystallization grains first nucleate at twin boundaries and have a 30 ° <0001> orientation difference from the twin matrix. Under large strain, small dynamic recrystallization grains were formed in the alloy structure near the original large grains, and the cumulative micro-orientation from the inside of the original large grains to the grain boundaries increased continuously, thus confirming the continuous dynamic recrystallization of the alloy . The dynamic recrystallization mechanism of particle-excited nucleation was also found in the alloy.