三级时效7N01铝合金微观结构与力学性能关系的研究

The microstructure of a three-step-aged 7N01 aluminum alloy in relation with its mechanical properties

本文针对一种有实际应用前景、经历了三级时效的7N01铝合金,采用透射电镜观察和力学性能测试,系统研究了该合金力学性能与析出相微观结构的关系。研究结果表明,该种经历了三级时效状态的7N01铝合金,相比直接人工热处理的材料,屈服强度和抗拉强度均可获得显著提高,同时不损失延伸率。透射电镜观察发现,峰值时效状态下合金的主要强化析出相为η'相和GP区。而且自然时效形成的合金元素原子集团中有GP区生成,它们在人工时效阶段可以直接转化为η'相颗粒。经三级时效处理的合金强度在一定范围内与自然时效阶段形成的GP区的多少密切相关。

By transmission electron microscopy and mechanical property characterization,a 7N01 aluminum alloy,treated with a three-step-ageing process that was practically applicable,was studied systematically for its precipitate microstructures in relation with properties. It is shown that the three-step-aged alloy demonstrates apparently increased strength without loss of ductility,as compared with the directly one-step-aged alloy. Transmission electron microscopy observation shows that the major strengthening precipitates in the hardness-peak-aged sample are the η＇-precipitates and the Guinier-Preston（ GP） zones. Moreover,there exist the GP zones among the alloying elements atom clusters formed in the stage of natural ageing,and furthermore these GP zones may transform into the η＇-precipitates upon subsequent artificial-ageing. The strength of the three-step-aged alloy is associated with the numbers of the GP zones formed in the first step of natural ageing in the three-step-ageing process to some extent.