Al-6.3Zn-2.8Mg-1.8Cu铸造铝合金的组织和室温力学性能

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

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 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.