Diffusion research between Ni 3Al coating and titanium alloy produced by plasma spraying process

Abstract

A Ni 3Al coating was prepared by plasma spraying technique on the surface of titanium alloy. Ni–Al mixed powders, coatings and reaction products were investigated by scanning electron microscope, EDS, DSC and XRD. A tight bonding between the coating and the substrate was formed. The X-ray diffraction analysis of the patterns showed that the coating not only had Ni 3Al phase, but also had NiO and Al 2O 3 phase microcontent. Comparing Ni coated Al to Ni 3Al at 900 °C, the diffusion was stronger and the diffusion layer was thicker. A minute pore structure was formed at 1200 °C in the front edge of solid-state reaction layer. So Ni 3Al restrained the solid-state reaction of the coating with the substrate, and as a whole weakened the entry of oxygen atoms into the substrate and quenched the out-diffusion of titanium.