Accelerated sintering and microstructural regulation of tungsten powder compact by novel modulation of particle configuration

Increasing the sintering rate of powder compact is a critical challenge of powder metallurgical materials, and adjusting component distribution in particles aggregate present significant effect on the microstructure of sintered product, especially for multi-phase compact with local heterogeneity. Here, a case study of W-Ni-Co powder compact was adopted to illustrate the novel strategy to enhance the sintering of multi-phase compact with desired microstructure by adjusting the particle configurations. The plasma synthesis route was developed for the first time to independently adjust the configurations of W-Ni-Co nanopowders with core-shell and homogeneous structures, which facilitates to ascertain the sintering response induced exclusively by particle configurations. Comparison on sintering response further indicates that core-shell powder presents greatly promoted sintering than homogeneous one, and full-dense and uniform compact with grain size of 1.37 μm was obtained by solid sintering, which is several to dozens of times smaller than that obtained by conventional liquid sintering. Theoretical and experimental Investigation on elemental immigration visualized the distinct mass diffusion behavior of powder compacts, and clarified the mass transport path promoted densification mechanism determined by powder configurations. Importantly, full-coherent phase interface induced superior strength and plasticity in alloy sintered using core-shell powder, which highlights the importance of microstructural regulation on improving the mechanical property that superior than most of previously reported tungsten heavy alloys. In summary, this work paves a new way for fast sintering of multi-phase compacts, and provides intrinsic understandings on densification mechanism of powder compact. Compared to homogeneous W-Ni-Co nanoparticles, significantly accelerated densification and regulated microstructure were observed for sintering core-shell nanopowders, and theoretically clarified by the mass transport path promoted densification mechanism which is closely related to powder configurations. • W-Ni-Co nanopowders with core-shell and homogeneous structures were synthesized by thermal plasma route. • Novel mass transport path, which is closely related to powder configuration, promotes densification. • Full-coherent phase interface induces improved strength and plasticity in alloy sintered by core-shell powder.