Peculiarities of phase formation in the mechanosynthesized titanium carbohydride powders under short pulse selective laser alloying

Abstract

The authors analyze peculiarities of the phase formation and morphology of the titanium carbohydride coatings deposited on the steel substrates by means of short pulse selective laser alloying. Ti(C,H) powders with a particle size of 0.5–5 μm have been preliminarily produced by mechanical activation of titanium in petroleum ether. Heating up to 900°C results in the decomposition of the titanium carbohydride with the formation of TiC and Ti. The coatings deposited under laser alloying of carbohydride and steel substrate contain 50 vol.% of the “core–shell” inclusions with TiC as a core and TiFe₂ and TiFe intermetallic compounds as a shell. Inclusions are of rounded shape both with a size of 50 to 200 nm, and the dendritic one is of up to 5 μm. Coatings up to 10 microns thick have a gradient pore-free structure and do not wear out under dry friction on hardened steel. Their microhardness is of 1016 HV, with a friction coefficient being 0.2. The proposed new in-situ technique for producing titanium-carbide-based coatings may be used for developing other metal carbide coatings with high performance characteristics.