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研究了Al-6.3Zn 2.8Mg-1.8Cu铸造铝合金的组织和室温力学性能.研究表明,在金属型铸造条件下,Al-6.3Zn-2.8Mg-1.8Cu合金的铸态组织为近等轴晶,相组成为α(Al)基体、枝晶间α(Al)+η(MgZn_2)共晶、晶内游离η相(MgZn_2)、少量T相(Mg_3Zn_xCu_3-_xAl_2)及少量颗粒状Al_7Cu_2Fe.固溶处理后,原铸态组织中的η(MgZn_2)相大部分溶解消失,但形成新的沿晶界分布的S相(Al_2CuMg).实验确定了固溶态Al-6.3Zn-2.8Mg-1.8Cu合金较优的单级和双级时效工艺.与单级时效工艺相比,采用双级时效工艺处理后,抗拉强度由480 MPa增加至490 MPa,延伸率由0.2%增加至2.2%.
The microstructure and room temperature mechanical properties of Al-6.3Zn 2.8Mg-1.8Cu cast aluminum alloy were studied.The results show that the as-cast microstructure of Al-6.3Zn-2.8Mg-1.8Cu alloy is nearly equiaxial The phase composition is α (Al) matrix, α (Al) + η (MgZn_2) eutectic, free η phase (MgZn_2), a small amount of T phase (Mg_3Zn_xCu_3-_xAl_2) and a small amount of granular Al_7Cu_2Fe After solution treatment, most of the η (MgZn 2) phase in the as-cast as-cast microstructure disappears, but a new S phase (Al 2 CuMg) distributes along the grain boundaries. The solid solution state of Al-6.3Zn-2.8Mg-1.8 Cu alloy.The results show that the tensile strength increases from 480 MPa to 490 MPa and the elongation increases from 0.2% to 2.2% compared with the single-stage aging treatment.