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通过XRD衍射分析、光学和透射电镜观察以及力学性能测试,研究了固溶和时效处理对粉末热挤压法制备的Al-Zn-Mg-Cu高强铝合金组织性能的影响。结果表明:挤压态合金中析出大量MgZn2相;合金适宜的T6热处理制度为460℃×2.5h水冷+120℃×24h空冷;在此条件下合金的抗拉强度、屈服强度和伸长率分别为731MPa、670MPa和6.2%;晶粒细化是合金T6组织与铸锭挤压Al-Zn-Mg-Cu合金回归再时效(RRA)组织类似的主要原因。
The effects of solution treatment and aging treatment on the microstructure and properties of Al-Zn-Mg-Cu high-strength aluminum alloy prepared by powder hot extrusion were investigated by XRD, optical and transmission electron microscopy and mechanical properties tests. The results show that a large amount of MgZn2 phase is precipitated in the as-extruded alloy. The suitable T6 heat treatment is 460 ℃ × 2.5h water cooling + 120 ℃ × 24h air cooling. Under these conditions, the tensile strength, yield strength and elongation of the alloy are 731MPa, 670MPa and 6.2%, respectively. The grain refinement is the main reason for the resemblance of the alloy T6 microstructure to the regressive re-aging (RRA) microstructure of ingot extruded Al-Zn-Mg-Cu alloy.