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采用扫描电镜、差热分析仪和X射线衍射仪分析粒度对气雾化过共晶Al-Si合金粉末形貌、组织和结构的影响,并计算粉末的过冷度和冷却速度。结果表明:粉末形貌规则性随粒度减小而得到改善,但Si相分布均匀性降低;同时,初晶Si相尺寸逐渐减小,形貌由不规则状转为块状;共晶Si相由不均匀针状转为网络状。随粒度减小,Al基体衍射峰发生宽化和偏移,同时热效应前移。过冷度和冷却速度随粒度减小而增大,这是导致粉末间组织和结构差异的根本原因。
The influence of particle size on the morphology, microstructure and structure of the atomized hypereutectic Al-Si alloy powder was analyzed by scanning electron microscopy, differential thermal analyzer and X-ray diffraction. The supercooling degree and cooling rate were calculated. The results show that the regularity of powder morphology is improved with the reduction of grain size, but the uniformity of Si phase distribution is decreased. Meanwhile, the size of primary Si phase decreases gradually and the morphology changes from irregular to massive. From non-uniform needle into network-like. As the grain size decreases, the diffraction peak of Al matrix expands and shifts, and the thermal effect moves forward. Undercooling and cooling rates increase with decreasing particle size, which is the root cause of the differences in the structure and structure of the powder.