Effects of Reinforced Particles on Dynamic Recrystallization of Mg Base Alloys during Hot Extrusion

摘要:

主要研究了SiC颗粒增强镁基复合材料在不同挤压比、不同挤压温度下进行挤压后，SiC颗粒对镁合金基体中的动态再结晶现象影响。结果表明：挤压过程中颗粒周围产生了颗粒变形区 (PDZ)，并且颗粒变形区在低温挤压时以细小动态再结晶晶粒为主。颗粒促进动态再结晶晶粒形成的主要原因是颗粒周围较高的位错密度以及大的晶粒取向梯度。SiC颗粒对镁合金基体动态再结晶的影响主要有两方面：一方面，颗粒促进动态再结晶的形核以及生长，另一方面，当再结晶晶粒晶界碰到颗粒时，颗粒阻止了晶粒的继续长大。

Abstract:

SiC particles reinforced Mg base composites were extruded at different temperatures and extrusion ratios. The effects of particles on dynamic recrystallization (DRX) of Mg matrix during hot extrusion were investigated. The results reveal that particle deformation zone (PDZ) is formed near a particle during hot deformation, and the PDZ is a characteristic of fine DRX grains in the composites extruded at lower temperatures. Particles promote DRX nucleation of Mg matrix during hot extrusion which may be attributed to high density dislocations and large orientation gradients in PDZ. Particles promote the growth of fine DRX grains until PDZ is consumed by DRX grains. On the contrary, at the stage when DRX grain boundaries contact with particles, particles pin grain boundaries and then retard grain growth.