Effects of Ni/Co ratio and mechanical alloying on characteristics and sintering behavior of W-Ni-Co tungsten heavy alloys

W-Ni-Co tungsten heavy alloys with a varied Ni/Co ratio produced by mechanical alloying have been investigated in this study. The change of the Ni/Co ratio and the processing of mechanical alloying are important to influence characteristics and sintering behavior of the model materials. The results show that the high Ni/Co ratio facilitates the process of solid phase sintering and promotes a fine-grained structure and a relatively high hardness. However, the behavior of liquid phase sintering was found in the alloys with the low Ni/Co ratio condition, corresponding to a coarse-grained structure and decrease in hardness. The mechanisms of the transition between the solid and liquid states during sintering has been discussed in this work, which can be associated with the amount of binder phase and its composition, tungsten grain size, deformation strain and sintering conditions.