(沈陽工業(yè)大學 材料科學與工程學院，沈陽 110870)
摘 要: 對Al-1Si-0.3Mg和Al-7Si-0.3Mg合金在-80~20 ℃拉伸過程中的斷裂行為進行研究。結果表明：隨著溫度的降低Al-1Si-0.3Mg合金的抗拉強度、屈服強度及伸長率均呈上升趨勢；Al-7Si-0.3Mg合金的抗拉強度和屈服強度上升，伸長率卻明顯下降；拉伸過程中Al-1Si-0.3Mg合金中位錯在晶界塞積，易使相鄰晶粒內位錯源啟動，使合金具有較高的塑性；Al-7Si-0.3Mg合金的位錯在Si相邊界塞積，使相鄰晶粒內位錯源難以啟動，從而造成合金具有較高的強度。
關鍵字: 鋁硅合金；低溫；拉伸性能；位錯；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
