Al-6.3Zn-2.8Mg-1.8Cu铸造铝合金的组织和室温力学性能

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（MgZn₂）共晶、晶内游离η相（MgZn₂）、少量T相（Mg₃Zn_xCu₃-_xAl₂）及少量颗粒状Al₇Cu₂Fe.固溶处理后,原铸态组织中的η（MgZn₂）相大部分溶解消失,但形成新的沿晶界分布的S相（Al₂CuMg）.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%.

MICROSTRUCTURES AND ROOM TEMPERATURE MECHANICAL PROPERTIES OF Al-6.3Zn-2.8Mg-1.8Cu CASTING ALUMINUM ALLOY

The microstructures and room temperature mechanical properties of metal-mold- casting aluminum alloy Al-6.3Zn-2.8Mg-l.8Cu were studied.It was found that the microstructure of the as-cast experimental alloy consists of near equiaxed a(Al) matrix,a(Al)+rj(MgZn2) eutectic and little AlyC^Fe particle phase.The phase constitution of the quenched experimental alloy was changed,the r\ phase was dissolved into a(Al) matrix and tended to disappear,however a new phase, S(Al2CuMg),appeared,which still mainly distributed along the a(Al) grain boundary.The opti- mum single-aging process parameters were determined by investigating age hardening response of the experimental alloy.It was found that the double-aging process could make the tensile strength of the experimental alloy increase from 480 MPa to 490 MPa,and the elongation from 0.2%to 2.2%, comparing with the single-aging process.