Effect of laser parameters on microstructure and phase evolution of Ti-Si-C composites prepared by selective laser melting

In this paper, blended Ti/SiC powder was processed by selective laser melting (SLM) method to prepare a novel kind of Ti-Si-C composite. Microstructure, elements distribution and phase evolution of Ti-Si-C composites fabricated by SLM were studied. SEM, EDS, TEM and XRD were performed to evaluate the microstructure and phase evolution during the SLM process. The results showed that processing parameters significantly affected the microstructure and element distribution of the samples. It was found that higher laser energy density could promote the densification process and hence suppress balling phenomenon of Ti-rich phases. At the micro-level, the microstructure could be classified into the dense area and the porous area, which was closely related to the redistribution of elements. The phases obtained by the SLM process were composed by TiCx, TiSi2, Ti5Si3, and Ti5Si4, which appeared in different microstructures. The results indicated that composites with different phases and microstructure could be obtained by merely modifying laser processing parameters, which could give experimental guidance for the fabricating of gradient Ti-Si-C composites by selective laser melting without additional apparatus on powder feeding.