(1. 西安交通大学 材料科学与工程学院，西安 710049；
2. 西安交通大学 金属材料强度国家重点实验室，西安 710049)
摘 要: 利用电导率、显微硬度和宏观拉伸测试，结合SEM、TEM、APT和XRD等表征手段对Al-Zn-Mg合金中的团簇长大动力学以及团簇对合金变形断裂的影响进行了研究。结果表明：Al-Zn-Mg合金经过约1000 h自然时效进入稳定状态，基体中形成了超高密度的Mg-Zn团簇，材料得到有效强化；人工时效态Al-Zn-Mg合金中析出相随高温时效时间的延长发生长大，类型以亚稳η′与稳定η相为主，部分析出相逐渐不可被位错切过。T6/T7态合金小应变下可迅速形成大量位错引起材料强化，但在大应变时会发生剧烈的动态回复，造成其较弱的加工硬化能力与较低的均匀伸长率(约13%)；而在T4态Al-Zn-Mg合金中，团簇和溶质原子的存在能有效抑制动态回复，并可在变形时伴生动态应变时效效应，造成材料较强的加工硬化和更优的均匀延伸性能(约25%)。
关键字: Al-Zn-Mg系铝合金；溶质原子团簇；三维原子探针；长大动力学；加工硬化
（1. School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China;
2. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China）
Abstract:The clusters growth kinetics and the deformation properties in natural-aged Al-Zn-Mg alloy were investigated by electrical conductivity, microhardness and tensile tests. Multiple characterization methods including SEM, TEM, APT and XRD were applied to reveal the microstructure features. The results show that through the natural aging of about 1000 h, the high number density of solute clusters forms in 7B05 alloy and are responsible for the natural aging hardening effect. Natural-aged Al-Zn-Mg alloy exhibits better strain-hardening properties and uniform elongation than their thermally treated counterparts. The presence of shearing-resistant precipitates in thermal-treated alloys results in rapid accumulation of dislocation loops around precipitates at small strain whereas at large strain, the dislocation dynamic recovery process is dominant. In natural-aged Al-Zn-Mg alloy, the dislocation recovery is inhibited by solutes and clusters, meanwhile, the dynamic strain aging effect raises the resistance of dislocation movements, both leading to a greater strain-hardening capability.
Key words: Al-Zn-Mg alloy; solute atom clusters; atom probe tomography; growth kinetics; strain-hardening properties
