Comparative study of microstructures and mechanical properties of in situ Ti-TiB composites produced by selective laser melting, powder metallurgy, and casting technologies

摘要

This study presents results of selective laser melting (SLM), powder metallurgy (PM), and casting technologies applied for producing Ti-TiB composites from Ti-TiB_2 powder. Diffraction patterns and microstructural investigations reveal that chemical reaction occurred between Ti and TiB_2 during all the three processes, leading to the formation of Ti-TiB composites. The ultimate compressive strength of SLM-processed and cast samples are 1421 and 1434 MPa, respectively, whereas the ultimate compressive strengths of PM-processed 25%, 29%, and 36% porous samples are 510,414, and 310 MPa, respectively. The Young's moduli of porous composite samples are 70, 45, and 23 GPa for 25%, 29%, and 36% porosity levels, respectively, and are lower than those of SLM-processed (145 GPa) and cast (142 GPa) samples. Fracture analysis of the SLM-processed and cast samples shows shear fracture and microcracks across the samples, whereas failure of porous samples occurs due to porosities and weak bonds among particles.