Laser powder bed fusion of Mo₂C/Ti-6Al-4V composites with alternately laminated α′/β phases for enhanced mechanical properties

• Main Authors: Cai, Chao, Qiu, Jasper Chua Dong, Shian, Tey Wei, Han, Changjun, Liu, Tong, Kong, Ling Bing, Srikanth, Narasimalu, Sun, Chen-Nan, Zhou, Kun
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2022
• Subjects: Engineering::Mechanical engineering; Laser Powder Bed Fusion; Metal Matrix Composite
• Online Access: https://hdl.handle.net/10356/159865
• Institution: Nanyang Technological University

Mo2C/Ti64 composites with nearly full densification and enhanced tensile strength were developed by using laser powder bed fusion (LPBF). The addition of 1-3 wt% Mo2C particles with an average particle size of similar to 1 mu m enabled the LPBF-printed composites with an alternately laminated alpha'-Ti/beta-Ti microstructure along with Mo2C and in-situ synthesized M23C6 (M was Ti, Al, V, and Mo). During LPBF, most of the Mo2C particles were incorporated into the Ti64 matrix, resulting in the alpha'-Ti and beta-Ti solid solutions. The segregation of Mo contributed to the generation of the beta-Ti phase at the melt pool boundaries of the composites, leading to the alternating hard alpha'-Ti/soft beta-Ti phases. Remarkable improvements of 22.8% and 19.5% in the hardness and tensile strength of the Ti64 matrix were achieved, respectively. The strengthening of the LPBF-printed composites was associated with the formation of the laminated alpha'-Ti/beta-Ti structure, solid solution behavior of Mo and C, and presence of the remaining Mo2C and precipitated M23C6. The findings are anticipated to provide insights into the selection of reinforcement materials for additively manufactured composites with nearly full densities and greater mechanical strength.