Laser Powder Bed Fusion of Diamond/N6 Mmcs Enabled by Ni-Ti Coated Diamond Particles

Abstract

There is a growing interest in additive manufacturing (AM) of metal matrix composites (MMCs). However, it remains challenging to control the composite powder preparation for MMCs and the AM processing parameters. In this study, the diamond particles are firstly coated with Titanium and Nickel to improve wettability with the Nickel powder. The ball milling parameters for the Ni-Ti coated diamond/N6 composite powder particles preparation and the powder bed fusion (LPBF) parameters for the MMC samples are optimized. It shows that highly flowable composite powder particles are obtained under a ball milling time of 4 h, a speed of 250 rpm, and a ball-to-powder ratio of 2:1. Meanwhile, the composite powder particles experience varying degrees of plastic deformation, cold-welding, and fracture during the ball milling. With the optimized composite powder, a set of MMC samples are further manufactured by LPBF. Under the laser powers of 150-170 W and scanning speed of 250 mm/s, the relative density of MMC samples is higher than 99% without obvious pores or cracking. Our study demonstrates the feasibility of manufacturing dense diamond/N6 and other similar MMCs with appropriate coating, ball milling, and LPBF parameters, even though the wettability between the reinforcement and matrix is poor.

Keywords: metal matrix composites, diamond, coating, Ni-based composites, ball milling, laser powder bed fusion