Effects of hexagonal boron nitride content on forming quality and performance of laser powder bed fusion manufactured nickel-based hastelloy X composites

Regulating the composition of nickel -based composites, especially those containing crack-sensitive Hastelloy X (HX) matrix, significantly influences the forming quality and performance of parts manufactured using laser powder bed fusion (LPBF). Ray tracing and temperature field simulations were conducted to analyze the nonequilibrium solidification mechanism of the laser processed hexagonal boron nitride (h-BN)-HX system, resulting in an optimized h-BN content range. The optimized composition, with 0.2 wt% h-BN in HX, showcased the best forming quality and performance. It displayed negligible cracks or unmelted particles, minimal surface roughness of 9.29 mu m, and superior tensile properties with a tensile strength of 1246.49 MPa and an elongation of 18.67 %. Furthermore, the samples showcased increased hardness (371.21 HV5) and reduced friction coefficient (0.54). Interestingly, with a further increase in h-BN content, a gradual improvement in strength and hardness was observed, accompanied by a reduction in the friction coefficient. Nevertheless, the ductility of the samples noticeably decreased. The 1 wt% h-BN/HX sample exhibited a tensile strength of 1503.14 MPa, hardness of 502.13 HV5, and friction coefficient of 0.48 while displaying an elongation of only 3.76 %. These findings emphasize the significance of optimizing the composition of Ni -based composites to enhance the forming quality and performance of parts manufactured through LPBF, particularly in aerospace and engineering applications.