Microporosity Evolution and Powder-Powder Interaction in Selective Laser Melting Process

Additive manufacturing in aerospace and biomedical applications is challenging due to the need of superior quality and liability of end products. A critical concern about the process is the formation of surface defects due to incomplete melting of powders and gas trapping between powders, which significantly weakens the mechanical performance of the raw products. Better understanding of the process dynamics can help to mitigate the defects and determine process control parameters. We present phase-field modeling of the powder-powder interaction and the formation of micropores during selective laser melting of pure titanium powders. The solid-liquid phase transition is coupled with thermal transport, capillary flow, and liquid-gas interfacial deformation. The change of morphology and the evolution of pores highly depend on the interplay of the fusion dynamics, configuration of powders, and laser control parameters.