7150铝合金时效时晶界析出行为的研究

Study on the precipitation behaviors at grain boundaries in 7150 aluminum alloys upon thermal aging

本文采用透射电子显微镜(TEM)、能谱分析(EDAX)对人工时效条件下晶界无析出带(PFZ)的演变规律进行研究。实验选用同一投影方向测量PFZ的宽度,结果表明PFZ的宽度对时效温度的敏感性远远高于对时效时间的敏感性。时效温度越高PFZ越宽,而在同一时效温度下PFZ的宽度并不随时效时间的延长而宽化。PFZ的宽度与相邻两个晶粒之间的取向差有关系,在相同处理条件下,小角度晶界附近PFZ宽度小于大角晶界。能谱分析显示PFZ内为贫溶质原子区,Zn元素缺失尤为明显。

The evolution of the precipitate free zones（PFZs） during artificial ageing,and the associated mechanical properties of 7150 Al alloy,have been investigated by means of transmission electron microscopy（TEM）,scanning transmission electron microscopy（STEM） and energy dispersive x-ray（EDS） analysis.A method for measuring the width of the PFZs has been proposed in order to observe the evolution of PFZs.It was found that the higher the aging temperature,the wider the formed PFZs.The ageing time has no significant effect on the width of PFZs at a fixed temperature.The width of PFZs is sensitive to the boundary types,the PFZs near small-angle grain boundaries are narrower than that near high-angle grain boundary.EDS data confirmed that alloying elements Zn and Mg were segregated into precipitates formed within grains or at grain boundaries.