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研究了不同铁相对铝硅合金高温拉伸性能及其断面显微组织、形貌的影响。结果表明:当合金中铁相形貌呈针状时,合金高温拉伸强度较好,但塑性较差;当合金中铁相形貌呈鱼骨状时,合金高温拉伸强度低于前者,但塑性较好。通过断面显微组织及断口形貌分析可知,含鱼骨状铁相的试样断口为典型塑性断裂特征,而含针状铁相的试样断口为典型脆性断裂特征。裂纹扩展均为沿晶断裂方式。
The effects of different iron phases on the tensile properties and microstructure and morphology at high temperature of Al-Si alloy were studied. The results show that when the iron phase morphology is acicular, the tensile strength of the alloy is better at high temperature but less plastic. When the iron phase morphology of the alloy is fish bone, the tensile strength of the alloy is lower than the former, but the plasticity better. According to the microstructure of the section and the analysis of the fracture surface morphology, the fracture of the sample containing the fish bone-like iron phase is a typical plastic fracture, whereas the fracture of the sample containing the acicular iron phase is a typical brittle fracture. Crack propagation are intergranular fracture mode.