(沈阳工业大学 材料科学与工程学院，沈阳 110870)
摘 要: 对Al-1Si-0.3Mg和Al-7Si-0.3Mg合金在-80~20 ℃拉伸过程中的断裂行为进行研究。结果表明：随着温度的降低Al-1Si-0.3Mg合金的抗拉强度、屈服强度及伸长率均呈上升趋势；Al-7Si-0.3Mg合金的抗拉强度和屈服强度上升，伸长率却明显下降；拉伸过程中Al-1Si-0.3Mg合金中位错在晶界塞积，易使相邻晶粒内位错源启动，使合金具有较高的塑性；Al-7Si-0.3Mg合金的位错在Si相边界塞积，使相邻晶粒内位错源难以启动，从而造成合金具有较高的强度。
关键字: 铝硅合金；低温；拉伸性能；位错；硅相
（School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China）
Abstract:The tensile mechanical properties of Al-7Si-0.3Mg and Al-1.0Si-0.3Mg alloys at -80-20 ℃were investigated. The mechanisms of crack initiation and extension at low temperature were analyzed. The results show that the tensile strength, yield strength and ductility of Al-1.0Si-0.3Mg alloy increase with decrease of temperature. The tensile strength and yield strength of Al-7Si-0.3Mg alloy increase, but the ductility of Al-7Si-0.3Mg alloy decreases with the decrease of temperature. During the low temperature tensile process, the dislocations pile up along the boundaries of grains in Al-1.0Si-0.3Mg alloy, which make dislocation sources to trigger easily in the adjacent grains, so the ductility of Al-1.0Si-0.3Mg alloy is improved. But the dislocations pile up at the Si particles in Al-7Si-0.3Mg alloy, which prevents the dislocation sources to trigger in the adjacent grains, so, the strengths of Al-7Si-0.3Mg alloy is greater.
Key words: Al-Si alloy; low temperature; tensile property; dislocation; Si phase
