A study on microhardness and microstructural evolution of titanium/zirconium diboride cermet coatings with varying scan speeds during laser cladding on Ti6Al4V substrate

Abstract

Titanium/zirconium diboride cermet coatings were deposited at different laser scan speeds on Ti-6Al-4V alloy using laser cladding technique. Microhardness of the coatings was compared with the microhardness of the substrate, while the microstructural morphologies of coatings were evaluated via scanning electron microscope with energy dispersive spectroscopy. In addition, resultant grain sizes of the coatings were observed and phases formed within the coatings were also examined. The microhardness of the coatings was seen to be four times harder than the substrate. Scanning electron microscopic images exhibited a refinement in grain size and the development of distinct microstructural features. X-ray diffraction patterns showed significant hard phases such as Al2Zr and Ti3B4 which may be responsible for the sky-rocketed microhardness values of the coatings. This study proffers profound insight on the influence of laser scan speed, during deposition, on the microhardness and microstructural morphology of titanium/zirconium diboride cermet coatings.