(中国兵器科学研究院 宁波分院，宁波 315103)
摘 要: 基于7A62铝合金的成分设计，研究Zn含量和Zn/Mg质量比对Al-Zn-Mg合金强度的影响。采用透射电镜(TEM和HREM)详细地研究7A62铝合金峰值时效的析出相，从多个晶体学方向观察了强化析出相的形貌及其与基体的关系。结果表明：Zn/Mg质量比为2~3、Zn含量增加至6.84%(质量分数)时，7A62合金的强度明显增加。峰值时效后，7A62合金基体形成了体积分数约60%、尺寸小于10 nm的沉淀强化相和体积分数约10%、尺寸为100~200 nm的弥散强化相。基体主要强化析出相是高密度均匀分布的η′相，与基体呈现半共格和晶体取向关系，形成较高晶格错配度；跨尺度位错缠结的弥散强化相是由Al、Zn、Mg、Mn元素组成的平衡相。7A62合金的化学成分和微结构特征使其成为高强可焊的铝合金。
关键字: 7A62铝合金；跨尺度；η′强化相；晶格错配；力学性能
（Ningbo Branch, China Academy of Ordnance Science, Ningbo 315103, China）
Abstract:The effects of Zn content and mass ratio of Zn and Mg on the strength of the Al-Zn-Mg alloys were investigated in order to develop a high-strength weldable 7A62 Al-alloy. The hardening precipitates of the 7A62 Al-alloy treated by peak aging were investigated in detail by transmission electron microscopy (TEM and HREM). The results show that the strength of 7A62 alloy with m(Zn)/m(Mg) of 2-3 and Zn content of 6.84% (mass fraction) increases obviously. After peak ageing, this alloy has the precipitates with volume fraction of 60% and the size ＜10 nm, and has the dispersed particles with volume fraction of 10% and the size of 100-200 nm. The high density uniformity η′ particles are the main strengthening precipitates in the matrix, and are semi-coherent or orientation relationships with the Al matrix, and form the high lattice mismatch. The trans-scale dispersed particles tangled by the dislocation are composed of Al, Zn, Mg, Mn elements. The new 7A62 aluminum alloy can become the high strength of weldable Al-Zn-Mg alloys due to the chemical composition and microstructure characteristics.
Key words: 7A62 aluminum alloy; trans-scale; η′ hardening phase; lattice misfit; mechanical properties
