Interfacial Microstructure Evaluation of Precisely Controlled Friction Stir Welding Joints of Al/Mg Dissimilar Alloys with Zn Interlayer

Abstract

In this study, a penetration-controlled friction stir welding (FSW) technique was employed to lap weld dissimilar Al/Mg alloys, incorporating a Zn interlayer. The joint’s microstructure, interfacial reaction, and phase composition were analyzed through optical microscopy, scanning electron microscopy, and X-ray diffraction. The findings demonstrate the formation of a hybrid joint comprising a FSWed region and a diffusion bonding region achieved by introducing a pure Zn interlayer at the Al/Mg interface. Within the FSWed region, the zinc was fully extruded, leading to favorable interface bonding. In contrast, the diffusion bonding region exhibited an aluminum–zinc diffusion reaction layer, an incompletely reacted zinc layer, and a zinc–magnesium diffusion reaction layer. Notably, no Al-Mg intermetallic compounds (IMCs) were observed in either the FSWed or diffusion bonding regions of the hybrid joint. This study further explored the underlying mechanism behind the joint’s formation.

Shoulder-Restricted Friction Deposition for Aluminum Alloy Coatings on Titanium Alloys

“…Moreover, the solid connection between the Al and Ti relies on intermetallic compounds (IMCs) with suitable thicknesses [5,7,15,16]. Without the formation of IMCs, the strength of the joint would be low due to insufficient metallurgical properties [15,[17][18][19], while IMCs that are too thick would make the joint brittle instead [20,21]. Wu et al investigated if IMCs with suitable thicknesses could be achieved by tailoring the heat input [5].…”

Subregion Based Prediction of Residual States in Friction Stir Welding of Dissimilar Metals

“…Friction stir welding (FSW), as a solid-state joining technology, offers several advantages when it comes to joining dissimilar metals [1-5], including Al/Cu [6][7][8], Al/Ti [9][10][11], Al/Al [12][13][14], Al/Mg [15][16][17], and Al/Steel [18][19][20]. Due to the formation of intermetallic compounds and element diffusions, the mechanical properties can differ significantly from the parent metals after FSW.…”