Growth morphologies and mechanisms of TiC grains during Selective Laser Melting of Ti-Al-C composite powder

Selective Laser Melting (SLM) was used to consolidate the high-energy ball milled Ti-Al-C composite powder. The morphologies of the in-situ formed TiC grains under different laser processing parameters were investigated. it showed that with increasing the applied laser powers, the TiC grain morphologies experienced successive changes from a laminated shape to an octahedron shape, and then to a truncated near-octahedron shape, and finally to a near-spherical shape. It was believed that the continuously elevated SLM operating temperatures induced by the increasing laser powers played an important role in determining the TiC grain morphologies. Reasonable metallurgical mechanisms for grain growth behind the microstructural developments were proposed. (C) 2009 Elsevier B.V. All rights reserved.