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制备了新型高Zn含量的Al-11Zn-2.4Mg-2.1Cu-0.1Zr高强铝合金,分析了淬火温度、深冷处理及时效工艺对合金微观组织与力学性能的影响。结果表明,随着淬火温度降低,淬火冷却速度与过饱和固溶体的固溶度连续增加,时效相变驱动力大幅提升,沉淀强化相的析出尺寸不断减小,晶内与晶界析出的强化相数量与析出密度大幅提升,抗拉强度随之提高。深冷处理的作用机制主要为预时效机制,受构件的体积和尺寸影响较大;与135℃×16h时效工艺相比,合金经120℃×24h时效处理后,晶内与晶界均析出了大量细小弥散分布的GP区与η’沉淀强化相,合金时效强化效果最佳,其平均抗拉强度、屈服强度与伸长率分别为716 MPa、702 MPa与8.9%。
A new high-content Al-11Zn-2.4Mg-2.1Cu-0.1Zr high-strength aluminum alloy with high Zn content was prepared. The effects of quenching temperature, cryogenic treatment and aging treatment on the microstructure and mechanical properties of the alloy were analyzed. The results show that with the decrease of quenching temperature, the quenching cooling rate and the solid solubility of supersaturated solid solution increase continuously, the driving force of aging transformation increases greatly, the precipitation size of precipitated strengthening phase decreases, and the precipitated strengthening phases The number and precipitation density increased significantly, tensile strength increased. The mechanism of cryogenic treatment is mainly pre-aging mechanism, which is greatly affected by the volume and size of the components. Compared with the aging treatment at 135 ℃ × 16h, the alloy precipitated a large amount of grain and grain boundary after aging at 120 ℃ for 24h The finely dispersed GP zone and η ’precipitation strengthened phase have the best effect of aging strengthening. The average tensile strength, yield strength and elongation are 716 MPa, 702 MPa and 8.9% respectively.