铝铜真空固相扩散焊焊缝微观组织研究

Research on Microstructure of Aluminum-copper Weld by Vacuum Diffusion

复合罩体零件由T2铜罩和7A09铝罩经过真空固相扩散焊连接成形。综合运用金相显微镜、显微维氏硬度计、扫描电子显微镜、X射线能谱仪、X射线衍射仪对焊缝微观组织结构进行研究。结果表明:焊缝由多种脆性相组成,焊缝与母材之间形成了明显的扩散层,焊缝及扩散层宽度约0.3 mm;两侧扩散层宽度及组织呈明显差异,铝侧扩散层宽度远大于铜侧扩散层,在铝侧扩散层生成了以网状特征为主的脆性相,并在焊接温度和应力的共同作用下晶粒发生了动态再结晶,扩散层与焊缝组织呈明显的过渡梯度,铜侧扩散层生成了致密带状脆性相,过渡梯度不明显。

A composite covering part formed by vacuum solid diffusion wending of T2 copper cover and 7A09 aluminum cover.The weld microstructure was studied with metallographic examination,micro hardness testing,SEM,EDS and XRD. The results show that the weld is made of various brittle phases. An obvious diffusion layer formed between weld metal and base metal. The width of the weld and diffusion layer is about 0. 3 mm. The width and tissue of both sides of the diffusion layer showed an obvious difference. The diffusion layer width of the aluminum side is much larger than that of the copper side. Brittle phase with primary mesh characteristics formed at the aluminum side diffusion layer and dynamic recrystallization occurred under the co-effect of welding temperature and stress. The diffusion layer and the weld microstructure presents obvious transitional gradient. The copper side diffusion layer generated a dense band brittle phase,and transition gradient is not obvious.