Cu含量以及Cu/Mg比对Al-Si-Cu-Mg合金组织和力学性能的影响

Effects of Cu Content and Cu/Mg Ratio on the Microstructure and Mechanical Properties of Al-Si-Cu-Mg Alloys

研究了Cu含量和Cu/Mg比对Al-Si-Cu-Mg合金组织和力学性能的影响。结果表明Al-Si-Cu-Mg合金凝固组织是否形成Mg_(2)Si、Q-Al_(5)Cu_(2)Mg_(8)Si_(6)以及θ-Al_(2)Cu取决于Cu含量以及Cu/Mg比。当Cu/Mg比相对低时形成Mg_(2)Si中间相,而Cu/Mg比高时则倾向于生成Q-Al_(5)Cu_(2)Mg_(8)Si_(6)和θ-Al_(2)Cu相。当Cu/Mg比相同时,高Cu含量和高Mg含量都会促进Q相θ相的形成。通过观察T6热处理后的组织发现Cu含量以及Cu/Mg比控制了初生相的溶解以及析出相的形成,从而影响合金的强度与韧性。通过控制Cu含量及Cu/Mg比使Al-9Si-2Cu-0.5Mg合金中析出较少数量的初生相,再通过热处理析出大量的Q′强化相,使合金具有较高的强度和相对适中的伸长率。

The microstructure and mechanical properties of Al-Si-Cu-Mg alloys with different Cu contents and Cu/Mg ratios were investigated.The results showed that the Mg_(2)Si,Q-Al_(5)Cu_(2)Mg_(8)Si_(6) and θ-Al_(2)Cu intermetallic phases formed in the as-cast Al-Si-Cu-Mg alloys depending on the Cu content and the Cu/Mg ratio.The Mg_(2)Si was formed in the relatively low Cu/Mg ratio of alloy,while high Cu/Mg ratio promotes the formation of Q-phase and θ-phase.With the same Cu/Mg ratio,the high content of Cu and Mg elements simultaneously enhances the formation of Q-phase and θ-phase.Microstructural observation from the T6 tempered alloys revealed that the Cu content and the Cu/Mg ratio control the dissolution of primary intermetallic phases and the formation of precipitates,thus affecting the strength and the ductility.It was indicated that by controlling the Cu and the Cu/Mg ratio,the Al-9Si-2Cu-0.5Mg aged alloy with few primary compounds and a large number of fine Q′precipitates exhibits high strength and acceptable ductility.