(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 采用拉伸、剝落腐蝕、晶間腐蝕、電化學(xué)等測試手段，結(jié)合X射線衍射(XRD)、掃描電子顯微鏡(SEM)以及透射電子顯微鏡(TEM)等分析技術(shù)研究不同鎂硅比(2.2，1.3，1.0，0.8)對Al-Mg-Si合金顯微組織及性能的影響。結(jié)果表明：當(dāng)鎂硅比從2.2減小到1.3，會促進(jìn)合金強化相析出，Mg2Si相析出數(shù)量增加且尺寸變小，合金強度顯著提高；當(dāng)鎂硅比為1.0時，合金的綜合力學(xué)性能無明顯差異；鎂硅比的減小會降低合金的剝落腐蝕敏感性，同時會提高合金晶間腐蝕敏感性，但當(dāng)鎂硅比為1.0時，晶間腐蝕敏感性明顯改善；當(dāng)鎂硅比為1.0時，Al-Mg-Si合金晶界處無Mg2Si相連續(xù)分布，無明顯的無析出區(qū)，合金綜合性能最佳，抗拉強度、腐蝕速率分別達(dá)到303 MPa、5.12 μm/a。
關(guān)鍵字: Al-Mg-Si合金；鎂硅比；析出相；耐腐蝕性能；力學(xué)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
