半固态等温热处理对纳米SiC_P/AZ61镁基复合材料组织的影响

Effect of Semisolid Isothermal Heat Treatment on Microstructure of Nano SiC_p/AZ61 Magnesium Matrix Composites

在不同等温热处理工艺条件下,对纳米SiCP/AZ61镁基复合材料的组织演变进行了研究,并采用电子显微镜、SEM和XRD技术对其进行观察与分析。结果表明:在本试验条件下,等温时间在15～30 min之间,保温温度在595～605℃区间时,制备的n-SiCP/AZ61镁基复合材料半固态颗粒等效直径为30～80μm,圆整度为1.1～1.6,是理想的半固态组织;外加颗粒的存在与颗粒尺寸的减小使得复合材料在等温热处理过程中获得近球状半固态组织所需时间显著减小,同时晶粒直径也相对减小。

The microstructures evolution of SiC nano particles reinforced AZ61 magnesium composites by ultrasonic during semisolid isothermal heat treatment were investigated by means of electron microscopy, scanning electron microscopy and X-ray diffraction technique. The experimental results show that at 595 ℃, with the increase of holding time the microstructures of nano SiCp/AZ61 composites experience two stages successively characterized by the dendrites bailing and grains Ostwald ripening and growing. The best semi-solid structure of composites can be obtained at about 595 ℃ to 605 ℃ with a holding time of about 15 to 30 min; the equivalent diameter and the roundness of the grains in composites are about 30 to 80 μm and 1.1 to 1.6, respectively. During semisolid isothermal heat treatment, due to reinforced particles and their smaller particle size, the time needed to obtain near globular grains is significantly shortened, and the grains diameter of the composites is also relatively decreased.