Compaction and solid-state sintering of tungsten powders: MPFEM simulation and experimental verification

Abstract

The uniaxial die compaction and solid-state sintering of different sized tungsten powders in powder metallurgy (PM) process was numerically reproduced in multi-particle FEM (MPFEM) modeling from particulate scale. The effects of particle size, initial packing structure, compaction pressure and sintering temperature on the relative density of the tungsten powder component were systematically studied and discussed. Various macroscopic and microscopic properties of the powder mass with different initial packing structures during compaction and sintering were characterized and analyzed. These properties include the overall relative density, local stress distributions, force structure and transmission, particle rearrangement and deformation, void filling behavior, as well as the densification dynamics and mechanism. The results show that by properly controlling the operating conditions such as initial packing structure, compaction pressure and sintering temperature, high performance PM component with high relative density, uniform density, stress, and void distributions can be obtained. Meanwhile, physical experiments were implemented to verify the simulation results. It is indicated that MPFEM modeling used in current work can provide the researchers with an effective method to simulate the whole PM process for refractory tungsten powders from particulate scale, especially the coupling of different stages can reduce the assumptions in the modeling and make the simulation results more accurate and much closer to the actual process.