Influence of Processing Parameters on Microstructural Development and Tribological Behavior of Spark Plasma Sintered Hard W-1.5 wt.% La₂O₃ and W-4 wt.% Y₂O₃ Composites

In this experimental study, the lanthanide- and yttria-reinforced hard tungsten-based composites were fabricated by mechanical alloying and spark plasma sintering processes. The precursor powders of pure W, Y₂O₃, and La₂O₃ oxides were mixed in given ratios and then milled in situ for 80 h in a planetary ball mill. The prepared powders were subsequently sintered at different sintering temperatures and times. Mechanically alloyed powders, consolidated samples, and their worn surfaces were characterized using scanning electron microscopy, X-ray diffraction, and Archimedes’ principle, respectively. A micro-Vickers hardness tester was employed to measure the hardness values of the sintered samples, whereas the wear characteristics were determined using a pin-on-disk tribometer test, conducted under dry sliding conditions. It was shown that the hardness and wear resistance of consolidated samples were improved with an increase in sintering temperature and time. Moreover, it was also noticed that La₂O₃ is found to be more effective in enhancing the sinterability, hardness, and wear resistance of tungsten matrix than Y₂O₃ particles. For the W-1.5 wt.% La₂O₃ composite at 1700 °C, it has the highest COF value of 0.11 and a minimum specific wear rate of 2.3 × 10⁻⁷ mm³/Nm was observed. However, the W-4 wt.% Y₂O₃ composite exhibited a COF value of 0.075 and a specific wear rate of 3.1 × 10⁻⁷ mm³/Nm under similar conditions.