Comparative investigations of the activated sintered W-l wt% Ni composites reinforced with various oxide and boride particles

摘要

The effects of different kinds of oxide (La_2O_3 and Y_2O_3) and boride (CrB_2, HfB_2 and ZrB_2) particles on the physical, microstructural and mechanical properties of the W-l wt% Ni matrix composites were investigated. Powder blends having compositions of W-l wt% Ni, W-l wt% Ni-1 wt% x, and W-l wt% Ni-1 wt% x-2 wt.% y (x = La_2O_3 and Y_2O_3; y = CrB_2, HfB_2 and ZrB_2) were mechanically alloyed (MA'd) for 12 h in a Spex~(TM) Mixer/ Mill with a rate of 1200 rpm using tungsten carbide vial and balls. MA'd powders were compacted to cylindrical preforms in a hydraulic press under a uniaxial pressure at 400 MPa and the green compacts were sintered at 1400℃ for 1 h under Ar/H_2 gas flowing conditions. Phase and microstructural characterization investigations of the MA'd powders and sintered composites were performed using X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) techniques. Density, Vickers microhardness and sliding wear tests were conducted on the sintered samples. The simpler systems of the hybrid composites (W-l wt% Ni, W-l wt% Ni-1 wt.% La_2O_3 and W-l wt% Ni-1 wt.% Y_2O_3) yield inferior mechanical properties than those of the hybrid composites. Among the fabricated hybrid composites, W-l wt.% Ni-1 wt.% La_2O_3-2 wt.% CrB_2 had the highest density value of 98.89% and W-l wt.% Ni-1 wt.% La_2O_3-2 wt.% HfB_2 had the highest microhardness value (7.97 ± 0.50 HV) and the lowest relative wear volume loss (0.37).