Interfacial voids and microstructure evolution, bonding behavior and deformation mechanism of TC4 diffusion bonded joints

• Published in: Journal of manufacturing processes 2022-09, Vol.81, p.837-851
• Main Authors: Peng, Yu, Li, Jinglong, Li, Zhaoxi, Li, Shiwei, Guo, Wei, Gao, Xiangyu, Xiong, Jiangtao
• Format: Article
• Language: English
• Subjects: Creep; Diffusion bonding; Interfacial microstructure evolution; Micro mechanism of deformation; TC4
• ISSN: 1526-6125; 2212-4616
• DOI: 10.1016/j.jmapro.2022.07.037

The interfacial voids closure and related microstructure evaluation of diffusion bonding process was studied by the method of combining simulation and experiment on TC4 joints. It was found that the interfacial microvoids of joints transformed narrow oval to rounded circle with the increase of bonding time. Meanwhile, the distance of two adjacent interfacial microvoids increased, indicating the improvement of the bonded ratio. At the tip of microscopic convex region, the initial boundary was replaced by recrystallized grains. At the voids neck region, the initial bonding interfaces were replaced by straight grain boundary for the inadequate deformation, resulting from the incomplete driven force of recrystallization and grain boundary migration. The bonded interface developed from straight grain boundary to grains across the original interface. The evolution of Mises equivalent stress fields and the local strain fields of the interfacial region were by Finite Element Analysis (FEA) method. The results indicated that the stress at the asperity tip region was always higher than that at the neck of the void. The distribution of dislocations on the bonding interface region demonstrated that the grain boundary migration was controlled by the multiple slip of dislocations, which controlled by Power-Law Creep mechanism. [Display omitted] •The morphology of interfacial voids evolved from narrow oval to rounded circle.•The degree of stress concentration on bonded region decreased over time.•Recrystallized grains and migrating grain boundaries replaced the initial interface.•The main creep mechanism of local micro convex region was Power-Law Creep.•The dislocations motion proved the Power-Law Creep mechanism on micro convex region.