(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 采用拉伸、剥落腐蚀、晶间腐蚀、电化学等测试手段，结合X射线衍射(XRD)、扫描电子显微镜(SEM)以及透射电子显微镜(TEM)等分析技术研究不同镁硅比(2.2，1.3，1.0，0.8)对Al-Mg-Si合金显微组织及性能的影响。结果表明：当镁硅比从2.2减小到1.3，会促进合金强化相析出，Mg2Si相析出数量增加且尺寸变小，合金强度显著提高；当镁硅比为1.0时，合金的综合力学性能无明显差异；镁硅比的减小会降低合金的剥落腐蚀敏感性，同时会提高合金晶间腐蚀敏感性，但当镁硅比为1.0时，晶间腐蚀敏感性明显改善；当镁硅比为1.0时，Al-Mg-Si合金晶界处无Mg2Si相连续分布，无明显的无析出区，合金综合性能最佳，抗拉强度、腐蚀速率分别达到303 MPa、5.12 μm/a。
关键字: Al-Mg-Si合金；镁硅比；析出相；耐腐蚀性能；力学性能
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The Al-Mg-Si alloys with four different Mg-Si ratios of 2.2, 1.3, 1.0 and 0.8 were prepared, respectively. The effects of Mg-Si ratio on the microstructures and properties of Al-Mg-Si alloys were investigated by tensile properties, exfoliation corrosion, intergranular corrosion and electrochemistry test, combined with XRD, SEM, TEM analysis techniques. The results indicate that the decrease of Mg-Si ratio from 2.2 to 1.3 can promote the strengthening phase precipitation which leads to higher number density and smaller size of Mg2Si precipitates, and the tensile strengths of alloys increase significantly. The mechanical properties of alloys trend to be stable when the Mg-Si ratio is 1.0. With the decrease of Mg-Si ratio, the exfoliation corrosion susceptibility of alloys decreases gradually and the resistance to intergranular corrosion decreases. But the resistance to intergranular corrosion of alloys can be improved significantly when the Mg-Si ratio is closer to 1.0. There are few continuous Mg2Si precipitates or PFZ on the grain boundaries of Al-Mg-Si alloys with Mg-Si ratio of 1.0. The comprehensive performance of Al-Mg-Si alloy reach the optimum properties, the tensile strength and corrosion rate reach 303 MPa and 5.12 μm/a when Mg-Si ratio is approximately 1.0.
Key words: Al-Mg-Si alloy; Mg-Si ratio; precipitate phase; corrosion resistance; tensile property
