【摘要】 研究Al-5.0Mg-3.0Zn-1.0Cu合金挤压铸造态、固溶态和时效态显微组织及力学性能随截面深度的变化规律。对于挤压铸造态合金,从表层到心部,α（Al）的晶粒尺寸和T-Mg₃₂（AlZnCu）₄₉相的宽度显著增加,而T-Mg₃₂（AlZnCu）₄₉相的体积分数显著下降,这些变化导致挤压铸造态合金抗拉强度从243.7 MPa降低到217.9 MPa,伸长率从2.3%降低到1.4%。在470°C下固溶处理36 h后,大部分第二相溶解于α（Al）基体中,并且表面和心部的晶粒尺寸均较挤压铸造态的增大,从表层到心部,合金的伸长率从18.6%降低到13.9%,抗拉强度从387.8 MPa降低到348.9 MPa。在120°C下进一步时效24 h后,在基体中析出G.P. II区和η’相,合金表层和心部的抗拉强度分别增加到449.5 MPa和421.4 MPa,而伸长率则降至12.5%和8.1%。更多还原

【Abstract】 The microstructure and mechanical properties at different depths of squeeze-cast, solution-treated and aged Al-5.0 Mg-3.0 Zn-1.0 Cu alloy were investigated. For squeeze-cast alloy, from casting surface to interior, the grain size of α（Al） matrix and width of T-Mg₃₂（AlZnCu）₄₉ phase increase significantly, while the volume fraction of T phase decreases. The related mechanical properties including ultimate tensile strength（UTS） and elongation decrease from 243.7 MPa and 2.3% to 217.9 MPa and 1.4%, respectively. After solution treatment at 470 °C for 36 h, T phase is dissolved into matrix, and the grain size increases so that the UTS and elongation from surface to interior are respectively reduced from 387.8 MPa and 18.6% to 348.9 MPa and 13.9%. After further peak-aging at 120 °C for 24 h, numerous G.P. II zone and η′ phase precipitate in matrix. Consequently, UTS values of the surface and interior increase to 449.5 and 421.4 MPa, while elongation values decrease to 12.5% and 8.1%, respectively.更多还原