Effects of Al ₂O ₃ addition on the microstructure and properties of Ni activated sintered W matrix composites

In the present investigation, fabrication of high dense (> 97.8%) W matrix composites with increased microhardness values were investigated. W and W-1 wt.% Ni powders were mechanical alloyed for 18 h and sintered at 1400°C for 1 h under Ar, H ₂ gas flowing conditions in order to investigate the effects of 1 wt.% Ni addition on the densification and properties of W. The effects of Al ₂O ₃ particles additions on the microstructural and physical properties of the sintered W-1 wt.% Ni sample were investigated. A 92.59% relative density value of the sintered W sample increased to 99.47% with the addition of 1 wt.% Ni. Moreover, despite the observed grain growth, microhardness values significantly increased from 2.81 ± 0.34 GPa to 4.07 ± 0.16 GPa with the addition of 1 wt.% Ni. The relative density values of the sintered W-1 wt.% Ni sample slightly decreased with increasing Al ₂O ₃ additions, a relative density value of 97.81% was measured for the W-1 wt.% Ni sample reinforced with 2 wt.% Al ₂O ₃ particles. As the average grain size of W in the sintered W-1 wt.% Ni sample decreased from 4.41 ± 1.71 μm to 1.29 ± 0.39 μm with the addition of 2 wt.% Al ₂O ₃ particles, the microhardness of the sample increased to 5.98 ± 0.31 GPa.