Numerical study on the warm compaction and solid-state sintering of TiC/316L composite powders from particulate scale

Abstract

Powder compaction and sintering are critical stages of powder metallurgy in manufacturing high performance particle reinforced metal matrix composites. In this paper, particulate scale numerical investigations on the warm compaction and solid-state sintering of TiC/316L composite powders with different particle size ratios (PSRs, R316L/RTiC) and TiC contents were performed using multi-particle finite element method (MPFEM) in two dimensions. The effects of PSR and TiC content, compaction pressure and temperature, and sintering temperature on the compaction and sintering processes were comprehensively analyzed. On this basis, a variety of macro- and microscopic analyses were conducted to further identify the densification dynamics and mechanisms. The results indicate that green compacts with higher relative density and more uniform stress distribution can be readily achieved by warm compaction. The large-scale plastic deformation of 316L particles caused by the cooperative actions of temperature and pressure is the main densification mechanism in warm compaction. During solid-state sintering, the improvement of relative density is mainly achieved by the vanishing or shrinkage of residual pores along with the growth of sintering necks, accompanied by the deformation of 316L particles. Large displacements of particles mainly occur in contacting areas of adjacent particles. Moreover, the equivalent stress in 316L particles is smaller than that in TiC particles. With the increase of PSR and TiC content, lower relative density of green compacts and sintered parts were obtained and more irregular morphologies of 316L particles can be observed.