Structural design, numerical examination and experimental approach of the multi-powder mixer for directed energy deposition

Abstract

This study demonstrates a novel design of a multi-powder mixer for developing advanced alloys and manufacturing functionally graded materials (FGM) via the directed energy deposition (DED) process. The three-dimensional structural mixer is composed of three modules, including an inert gas inlet, a multi-powder mixer cavity and an inert gas outlet. A combination of the analytical electronic balance, the electron-probe micro-analyzer (EPMA) based on the wavelength-dispersive spectrometer (WDS) method and the scanning electron microscope (SEM) based on the energy dispersive spectrometer (EDS) method was utilized to study the powder mixing effects of the multi-powder mixer. Computational fluid dynamics (CFD) simulation was implemented to examine the velocity of gas flow and its trajectory in the multi-powder mixer to establish an effective multi-powder mixing mechanism. The multi-powder mixer with converging Laval tubes, which generated sufficient energy and a certain amount of vortex for powder mixing, has shown extraordinary powder mixing stability.