Microstructure and mechanical properties of in-situ hybrid reinforced (TiB+TiC)/Ti composites prepared by laser powder bed fusion

• Published in: Journal of materials research and technology Vol. 30; pp. 9258 - 9273
• Main Authors: Wu, Lidong, Gao, Zhengjiang, Fan, Zhenhua, Liu, Chenghao, Liu, Yunzhong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2024; Elsevier
• Subjects: Heat treatment; Laser powder bed fusion; Mechanical properties; Microstructures; Titanium matrix composites; Mechanical properties; Laser powder bed fusion; Heat treatment; Microstructures; Titanium matrix composites
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2024.05.224

To address the problems of insufficient strength and low hardness in pure titanium, a new Ti–B–C powder system was used to prepare in-situ hybrid reinforced (TiB + TiC)/Ti composites by laser powder bed fusion (LPBF) technology. The influence of different TiB/TiC ratios on the hybrid reinforcement was investigated. When the TiB/TiC ratio is 1:1, the best hybrid reinforcement effect is achieved and the mechanical interlocking structure is formed between TiB and TiC. The structures enhance the strength of (TiB + TiC)/Ti composites significantly. Subsequently, the microstructures and mechanical properties of (TiB + TiC)/Ti composites were investigated by adjusting different TiB + TiC contents. As the TiB + TiC content increases, the grains are refined significantly and transform into equiaxed grains eventually, the preferred orientation disappears. When the TiB + TiC content is too high, severe agglomeration of TiB + TiC occurs, resulting in less noticeable improvement in strength and a rapid decrease in plasticity. Finally, the heat treatment of (TiB + TiC)/Ti composites was carried out. TiB and TiC are uniformly distributed. TiC coarsens significantly, and TiB exhibits a dual-scale effect. The higher the heat treatment temperature, the more favorable it is to improve the plasticity of titanium matrix composites (TMCs). The TMC2 after HT950 has a tensile strength of 879 MPa and an elongation of 11.7%, exhibiting excellent comprehensive mechanical properties.