摘要铝-锌-镁-铜系高强铝合金既具有纯铝低密度的性质，又具有高强韧、高抗腐蚀性 能，因而其适用的工业领域范围较为广泛，其优异的性能更是使其在飞机制造业中发 挥着重要的作用。但随着现代工业急速发展，对超高强铝合金的性能也提出了更高的 要求，因此，国内外的众多研究者也一直致力于高强铝合金的热处理工艺的研究。83558

本文以 7075 高强铝合金为研究对象，进行固溶处理和时效处理实验，采用布氏 硬度测试、电导率测试、蔡司金相显微镜、扫描电镜和能谱分析等分析方法，研究固 溶处理时间、双级时效处理时间对合金的微观组织和性能的影响。研究结果表明：

(1)固溶处理工艺状态对后续的时效处理具有重大的影响，7075 铝合金在 470℃、 水冷条件下，最佳固溶时间为 4 小时，此时合金组织中粗大的第二相较少，硬度和抗 应力腐蚀能力也处于相对优良的状态。

(2)7075 铝合金在 120℃的预时效、157℃的终时效、空冷条件下，最佳预时效时间为 3 小时，最佳终时效时间为 8 小时。这是因为高强铝合金的时效过程中会产生析 出相，即 GP 区、η 和 η′相，其中 GP 区和 η′相在合金中起主要强化作用。在预时效 3 小时、终时效 8 小时的条件下，合金组织形貌较好，强化相较多，硬度和抗应力腐蚀 性能较好，但时效时间的变化对抗应力腐蚀性能的影响不明显，并且时效处理对硬度 产生降低的作用。

毕业论文关键词：7075 铝合金；固溶处理；时效处理

Abstract Al-Zn-Mg-Cu high strength aluminum alloy not only has the properties of pure aluminum, but also has high strength, high tenacity and high corrosion resistance。 Therefore it is widely used in the industries and even used in the aircraft industry because of its excellent performance。 But with the rapid development of the modern industry, it also put forward higher request to the performance of the alloy。 And many researchers at home or abroad has been committed to improve the heat treatment technology of the high strength aluminum alloy。

This aiticle is based on the researches of the 7075 high strength aluminum alloy and there are some experiments include solution treatment and aging treatment。 It mainly used the results of the brinell hardness test, conductivity test, Zeiss metallographic microscope, SEM and EDS as the indicator to study the effects of solution time and aging time on the microstructure and property of the alloy。 The results of the experiments indicate as follows。 (1)Solution treatment has the significant effect on the subsequent aging treatment。 As the result of the study, it can be found that the best solution time was 4 hours under the

condition of 470℃ and water cooling。 At this time, there were less second phases which

were big in the microstructure and the hardness and the ability of resistance against stress corrosion were in a good state。

(2) The best primary aging time was 3 hours and the best secondary aging time was 8 hours under the condition of primary aging temperature 120 ℃ , secondary aging temperature 157℃ and air cooling。 In the process of aging, it will produce precipitated phase and they are GP zone, η phase and η′ phase, in which GP zones and η′ phase are the main strengthening phases in the alloy。 When the primary aging time was 3 hours and the secondary aging time was 8 hours, the microstructure was better and there were more strengthening phase。 And the hardness and the ability of resistance against stress corrosion were also in a good state。 But the changes of the aging time had little effect on the ability of resistance against stress corrosion。

Keywords: 7075 aluminium alloy; solution treatment; aging treatment

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