Microstructure evolution and high-temperature oxidation behaviour of selective laser melted TiC/TiAl composites

摘要

In this work, TiC ceramic particle reinforced TiAl-based composites were synthesized by selective laser melting (SLM) by using Ti, Al, and TiC multi-component powder. The results showed that a plenty of TiC dendritic crystals formed during the solidifying process. It was found that TiC dendrites exhibited three different modes of nucleation and growth, corresponding to the dissolution-precipitation of fully melted fine TiC particles, the epitaxial growth along the margin of partly melted TiC particle, and the recrystallization growth based on stressinduced nonequilibrium melting. Subsequently, the influence of laser energy density on microstructure evolution and high-temperature oxidation behaviour of SLM fabricated TiC/TiAl composites were investigated. At a high laser energy density of 189 J/mm(3), the relatively full dense SLM-fabricated part was obtained, accompanying the formation of a variety of TiC dendrites with the coarsening structure, which made a contribution to the elevated high-temperature oxidation resistance with a low oxidation kinetics constant of 1.32 x (-5)(6)(-12)(-1)(10)(mg)(cm)(h).