Microstructural evolution, mechanical properties and tribological behavior of B₄C-reinforced Ti in situ composites produced by laser powder bed fusion

• Main Authors: Du, Jingguang, Ren, Yaojia, Liu, Xinyan, Xu, Feng, Wang, Xiaoteng, Zhou, Runhua, Baker, Ian, Wu, Hong
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Engineering::Mechanical engineering; Laser Powder Bed Fusion; Titanium Composite
• Online Access: https://hdl.handle.net/10356/171761
• Institution: Nanyang Technological University

Based on the advantage of rapid net-shape fabrication, laser powder bed fusion (LPBF) is utilized to process B4C-reinforced Ti composites. The effect of volumetric energy density (VED) on the relative density, microstructural evolution, tensile properties and wear behaviors of B4C-reinforced Ti composites were systematically investigated. The LPBF-ed samples with high relative density (>99%) can be achieved, while the pores and un-melted powders can be observed in the sample owing to the low energy input (33 J/mm3). The additive particulates B4C were transformed into needle-like TiB whiskers with nano-scale while C dissolved in the Ti matrix. Fine-scale grains (<10 μm) with random crystallographic orientation can be achieved and the residual stress shows a downtrend as the VED increases. Through the analysis of the tensile and wear tests, the sample at 61 J/mm3 VED showed a good combination of strength and wear performance, with an ultimate tensile strength of 951 MPa and a wear rate of 3.91 × 10-4 mm3·N-1m-1. The microstructural evolution in VED changes and the corresponding underlying strengthening mechanisms of LPBF-ed Ti + B4C composites are conducted in detail.