Solid state diffusion welding of SiC reinforced aluminum alloy Al6061

Abstract

This doctoral thesis was carried out as part of a WBI scientific collaboration project between the University of Biskra directed by Pr. Zakaria BOUMERZOUG and the University of Mons in Belgium directed by Pr. Fabienne DELAUNOIS. The present work focuses on understanding the structural evolution during the synthesis of AA6061-SiCp composite through powder metallurgy route by varying the reinforcement percentage (7.5, 10 and 13 wt.% of SiCp), under two loads and during different sintering temperature 585°C, 600°C, 615°C and 630°C. The influence of compacting load, sintering temperature and different wight percentage of SiCp reinforcements and its effects on density, porosity and hardness, have been studied. This study also aims to investigate the solid state joining by using welding by diffusion process of fabricated Al6061-SiC nanocomposites (DB), in which the AA6061-SiCp is prepared from AA6061 powder with different amount of 7.5 wt.%SiCp, 10 wt.%SiCp, and 13 wt.%SiCp. The effects of reinforcement percentage holding time on weldability, microstructure and mechanical properties welded joints were studied. The joint quality was assessed by macro crosssectional examinations. The characterization techniques and testing were used in this work, including X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Vickers hardness and microhardness ((Hv), and density measurements. A successfully composite material was prepared by powder metallurgy process. A homogeneous distribution of silicon carbide particles (SiCp) in aluminum matrix and in the welded joint was observed. The hardness and density of the composite material increase with the increase of silicon carbide amount in aluminum matrix. The optimum sintering temperature was 600 °C. The hardness of the welded composite increases with increasing holding time at 520 ⁰C, the reinforced composite with 13 wt.% of SiCp and welded at 3 h have the optimum properties on the welded joint. Thus, solid-state diffusion welding technique is the suitable welding technique for joining AMCs composite materials.