Effect of Heat Treatment to Twin-Wire Arc Spraying Ni-5wt.%Al Coating on 6061-T6 Aluminum Alloy Diffusion

Abstract

In this study, Ni-5wt.%Al coating was fabricated on the 6061-T6 aluminum alloy substrate by twin-wire arc spraying technology. Through different heat treatment process, effect of microstructure and phase structure was studied with different temperature and time. Interface reaction mechanism of alloy coating/substrate and diffusion behavior of elements was discussed. Heat treatment was carried out at 400°C，480°C，550°C and respective for 4h, 24h, 48h. The XRD , SEM and EDS results showed that main phases of Ni-5wt.%Al original coating were composed of Ni solid solution, in addition to a small amount of Al2O3, NiO and Al4Ni3. Phase composition has basically not changed, interface of the coating/substrate occurred diffusion, which was controlled by the diffusion of Al atoms. Intermetallic compounds of NiAl3 and Ni2Al3 were formed in interface of coating/substrate, and interface diffusion area gradually was thickened.