Electropulse (“spark”) plasma sintering of tungsten and W+5%Ni nanopowders obtained by high-energy ball milling

The mechanisms of high-speed sintering of tungsten and W+5 wt.% Ni nanopowders obtained by high-energy ball milling (HEBM) have been studied. The phase composition, microstructure parameters, hardness and fracture resistance of the obtained samples were investigated. It is shown that the samples have high relative density, small grain size and increased hardness. It is established that the formation of strong intermetallic phases Me$_x$W$_y$C$_z$ and Me$_x$W$_y$, as well as MeO oxides occurs at SPS of mechanically activated nanopowders. The simultaneous increase in the content of intermetallic phases and reduction of the grain size leads to a non-monotone character of the dependence of the SPS activation energy on the HEBM time. It is shown that the main mechanism of SPS of tungsten W+5 wt.% Ni nanopowders is Coble creep.