Selective Laser Melting of In Situ TiB/Ti6Al4V Composites: Formability, Microstructure Evolution and Mechanical Performance

• Published in: Acta metallurgica sinica : English letters 2020-06, Vol.33 (6), p.774-788
• Main Authors: Su, Yue, Luo, Shun-Cun, Meng, Liang, Gao, Piao, Wang, Ze-Min
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Cooling rate; Corrosion and Coatings; Densification; Energy; Evolution; Formability; Grain size; Interfacial bonding; Investigations; Laser beam melting; Lasers; Materials Science; Mechanical properties; Metallic Materials; Microhardness; Microstructure; Morphology; Nanotechnology; Nucleation; Organometallic Chemistry; Particulate composites; Plasma sintering; Spectroscopy/Spectrometry; Temperature; Titanium alloys; Titanium base alloys; Titanium diboride; Tribology; Wear resistance
• ISSN: 1006-7191; 2194-1289
• DOI: 10.1007/s40195-020-01021-3

In the present study, a series of in situ TiB/Ti6Al4V composites were fabricated using selective laser melting. The formability, microstructure evolution and mechanical properties of the as-built samples added with different contents of TiB 2 were studied. It is found that the densification level is related to both the content of TiB 2 and laser energy density. The added TiB 2 reinforcement particle can spontaneously react with titanium and then form the TiB phase. The needle-like TiB phase tends to transform into dot-like particles with the decrease in energy density. Additionally, with the increase in TiB 2 content, the TiB phase is coarsened due to the increased nucleation rate and more reactions. The grain morphology is found to largely depend on the translational speed of solid–fluid interface determined by the temperature gradient and cooling rate. Also, the microhardness of the as-built TiB/Ti6Al4V composites is obviously improved. More interestingly, as the energy density increases, the microhardness of the as-built TiB/Ti6Al4V composites firstly increases and then decreases due to the synergy of grain size and different morphologies and distribution of TiB phases. The wear resistance of TiB/Ti6Al4V composites is far superior to that of Ti6Al4V alloy owing to the increased microhardness resulted from the uniform distribution of the hard TiB phase in the matrix.