三级时效7 N01铝合金微观结构与力学性能关系的研究

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。

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

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 theη′?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.