Microstructure Evolution of Mo-Based Composites During Selective Laser Sintering and Thermal Processing

In this paper, a novel preparation of Mo-based composites by selective laser sintering and post-treatment thermal processing techniques is described, which can be used to manufacturing refractory metal parts. Coating polymer and frozen grinding techniques investigation of polymer-coated Mo powder and its sintering parameters have been discussed. Then post-treatment process has been developed and refractory metal parts of Mo-Cu composites were gained, which are taken from the sinterstation in a 'green' semi-sintered state and then go through a furnace cycle. The process includes polymer degreasing, high temperature sintering and melting infiltration, which is sintering Mo framework by high temperature combining with Cu impregnation method. The microstructure evolution of post-treatment samples was investigated by scanning electron microscopy and energy dispersive spectroscopy analyzing means. The microstructure characterization of Mo-Cu composites is homogeneous compound structure of adhesive phase Cu linked with Mo grains. A concentration of phases is along grain boundaries and these phases distribute interaction. Between Mo grains and Cu zone, there is a medium changing zone, a width of 30∼50 nm. It is physical combination by diffusion means in Mo-Cu composites phase interface. Post-treatment processing mechanism is Mo framework solid-state sintering and Cu liquid-phase impregnation of melting/solidification.