Unlike common age-hardening materials, deformation prior to artificial ageing has been found to adversely affect the hardness of AA2040 aluminum alloy. To prevent this disadvantage, the effects of four different combinations of warm forming and artificial ageing at 200 °C on the microstructures and Vickers hardness of Al-5.1Cu-1.0Mg-0.4Ag aluminum alloy have been investigated. Among the four different combinations, the combination of 5% warm forming +1 h ageing yielded the lowest hardness value (154 HV), while that of 40 min ageing + 5% warm forming + 20 min ageing yielded the highest (169 HV). It is presumed that the proper timing of inducing dislocations by warm forming is decisive. The appropriate combination of warm forming and artificial ageing, i.e., 40 min + 5%+20 min treatment, produces a suitable amount of Ω phase during the first-stage ageing (40 min ageing), induces dislocations in the subsequent warm forming (5% deformation), and causes the significant amount of lath-like S phase to form on dislocations during the final-stage ageing (20 min ageing), thus enhancing the overall mechanical strength.

中文翻译：

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人工时效和温成形不同组合对Al-5.1Cu-1.0Mg-0.4Ag高强铝合金中Ω相和S相演变的影响

与常见的时效硬化材料不同，人工时效之前的变形已被发现会对 AA2040 铝合金的硬度产生不利影响。为了防止这一缺点，研究了温成形和200℃人工时效的四种不同组合对Al-5.1Cu-1.0Mg-0.4Ag铝合金显微组织和维氏硬度的影响。四种不同组合中，5%温成形+1 h时效组合的硬度值最低（154 HV），而40 min时效+5%温成形+20 min时效组合的硬度值最高（169 HV）。据推测，通过温成形引起位错的适当时机是决定性的。温成形与人工时效的适当组合，即40 min+5%+20 min处理，在第一阶段时效（40 min时效）过程中产生适量的Ω相，在随后的温成形中诱发位错（5 ％变形），并在最后阶段时效（20分钟时效）期间在位错上形成大量板条状S相，从而提高整体机械强度。