鎂硅比對(duì)Al-Mg-Si合金顯微組織與性能的影響

鎂硅比對(duì)Al-Mg-Si合金顯微組織與性能的影響Effects of Mg-Si ratio on microstructures and properties of Al-Mg-Si alloy

采用拉伸、剝落腐蝕、晶間腐蝕、電化學(xué)等測(cè)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(duì)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(huì)促進(jìn)合金強(qiáng)化相析出，Mg2Si相析出數(shù)量增加且尺寸變小，合金強(qiáng)度顯著提高；當(dāng)鎂硅比為1.0時(shí)，合金的綜合力學(xué)性能無(wú)明顯差異；鎂硅比的減小會(huì)降低合金的剝落腐蝕敏感性，同時(shí)會(huì)提高合金晶間腐蝕敏感性，但當(dāng)鎂硅比為1.0時(shí)，晶間腐蝕敏感性明顯改善；當(dāng)鎂硅比為1.0時(shí)，Al-Mg-Si合金晶界處無(wú)Mg2Si相連續(xù)分布，無(wú)明顯的無(wú)析出區(qū)，合金綜合性能最佳，抗拉強(qiáng)度、腐蝕速率分別達(dá)到303 MPa、5.12 μm/a。

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.

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