Reactive diffusion bonding of SiC p /Al composites by insert layers of mixed powders

Abstract

Mixed Al–Si, Al–Si–SiC and Al–Si–W powders were employed as insert layers to reactive diffusion bond SiC_p/6063 metal matrix composites (MMC). The results show that using mixed Al–Si–SiC powder as insert layers, SiC_p/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer, which result in the low shear strength of the joints reactive diffusion bonded by the insert layer of mixed Al–Si–SiC powder, even lower than those bonded by the insert layer of mixed Al–Si powder. The Ti added in the insert layer obviously improved the joint strength of the mixed Al–Si–SiC powder. Nearly all the W added into the insert layer of Al–Si–W reacts with Al to form intermetallic WAl₁₂ during bonding. The reaction between the W and Al facilitates the formation of a dense joint of high quality, in addition the WAl₁₂ has a reinforcing effect on the joints, which enables the joints bonded by the insert layer of mixed Al–Si–W powder to have a high shear strength.