Effect of different Ti doping modes on diamond/Cu–Sn composites forming via laser powder bed melting

Abstract

This study used laser powder bed fusion (L-PBF) to fabricate four composites: diamond/Cu–Sn, diamond/Cu–Sn doped with titanium (Ti), diamond/Cu–Sn doped with titanium carbide (TiC), and Ti-coated diamond/Cu–Sn, and explore their potential applications in diamond tool manufacturing. Additionally, the diamond content was consistently maintained at 1 vol% to systematically investigate the effect of different Ti incorporation methods on the diamond-matrix bonding, melt pool spreading, and mechanical properties of the Cu–Sn-based diamond composites during L-PBF processing. The comprehensive optimization of surface roughness, relative density, and three-point bending strength found that the Ti coating on the diamond particles was the most effective Ti introduction method. The Ti-coated diamond/Cu–Sn composite demonstrated an expanded process window with optimal laser parameters of a 300–700 mm/s scanning speed range and a 250–350 W power range. The Ti coating served dual functions of mitigating the laser-induced thermal damage to diamonds and significantly improving the diamond-Cu–Sn alloy wettability, which reduced the inter-track porosity. Compared to the uncoated diamond composites, the optimized composite achieved a peak relative density of 98.7 % and an 850 MPa bending strength at 350 W laser power and 300 mm/s scanning speed, representing 5.22 % and 36 % improvements, respectively. The microstructural analysis revealed in situ formation of TiC at the diamond–metal interfaces, substantially enhancing the interfacial bonding strength. This study elucidated the mechanism of TiC reactions generating robust carbides to strengthen interfacial chemical bonding, which provided novel insights for developing high-performance diamond-Cu–Sn tools using L-PBF.