Investigation of Interfacial Diffusion During Dissimilar Friction Stir Welding

Abstract

The objective of this study is to predict the thickness of intermetallic compound at the weld interface of dissimilar friction stir weld of Al 1050 and copper. The mechanical properties of the dissimilar friction stir weld are significantly affected by the intermetallic compounds formed during the process. The formation of intermetallic depends on the concentrations of the dissimilar materials, which are determined by their diffusion across the weld interface. A numerical model is developed which consists of Fick’s second law based diffusion model in conjunction with a thermo-mechanical model. The numerical model captures the movement of the interfaces between intermetallic species due to the diffusion of the Al. A representative friction stir butt weld is performed with Al 1050 alloy and pure copper. The thickness of the intermetallic layer at the weld interface is determined by scanning electron microscopy and energy dispersive spectroscopy mapping of the weld cross sections. Predicted intermetallic compound thickness is compared well against the experimental observation.