Effects of TiB2 and La2O3 Particle Reinforcements on the Tungsten Matrix Composites Fabricated by Mechanical Alloying and Activated Sintering

In this study, 1 wt.% Ni activated tungsten matrix composites (W1Ni) reinforced with different amounts of TiB2 and La2O3 particles were fabricated using mechanical alloying, cold pressing and pressureless sintering methods. In this scope, different amounts of TiB2 (3 and 4 wt.%) and La2O3 (0.5 and 1 wt.%) particles were incorporated into W1Ni matrix and mechanical alloying process was conducted for different durations (6 and 12 h). As-blended and mechanically alloyed powders were cold pressed using a uniaxial hydraulic press and green bodies were sintered under Ar/H2 gas flowing condition. The physical, microstructural and hardness properties of cold pressed and sintered W1Ni composites reinforced with different amounts of TiB2 and La2O3 particles were investigated. The addition of TiB2 and La2O3 reinforcements led an increase in the density and/or microhardness values of the composites. It was observed that mechanical alloying time had a significant effect on the properties and microstructure of the sintered products. The combined usage of 3 or 4 wt.% TiB2 with 1 wt.% La2O3 reinforcement resulted in the formation of W2B phase in addition to the dominant W phase after sintering. The highest relative density and microhardness values were obtained as % 92.14 and 6.27±1.54 GPa, respectively, for the W1Ni-3 wt.% TiB2-1 wt.% La2O3 composite after mechanical alloying for 6 h, cold pressing and sintering