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通过对铸造共晶Al-Si合金断口及析出相的分析研究了拉伸过程中基体内析出相的断裂特点.结果发现:拉伸过程中基体内初、共晶硅以穿晶断裂为主,这与颗粒内部存在的结构缺陷有关;直径小于2.0μm的初晶硅能够抑制二次裂纹的扩展.块状富铁相表现出穿晶断裂特点,鱼骨状富铁相中的微裂纹沿一次枝晶轴向生长.富铜相对裂纹扩展具有强烈地偏折作用;以富铁相为核心析出的富铜相能抑制富铁相中微裂纹的形成.提高合金中Cu含量可以降低富铁相的有害作用,改善合金的力学性能.
The fracture characteristics of the precipitated phase in the matrix during the drawing process were analyzed by analyzing the fracture and precipitated phase of the eutectic Al-Si alloy. The results show that the primary and eutectic silicon in the matrix during the drawing process are mainly transgranular fracture, This is related to the structural defects existing in the particles, and the primary silicon with the diameter less than 2.0μm can restrain the expansion of the secondary cracks.The massive iron-rich phase shows the transgranular fracture characteristics, and the micro-cracks in the fish bone- The dendrite grows in the axial direction, and the copper-rich phase has a strong deflection effect on the relative crack growth. The copper-rich phase precipitated in the iron-rich phase can inhibit the formation of microcracks in the iron-rich phase. Increasing the Cu content in the alloy can reduce the iron- The harmful effects, improve the mechanical properties of the alloy.