Effect of nano Y2O3 dispersion on thermal, microstructure, mechanical and high temperature oxidation behavior of mechanically alloyed W-Ni-Mo-Ti

Abstract The present research deals with the fabrication of mechanically alloyed W based alloys with nominal composition of W75Ni10Mo10Ti5 (alloy A), W74Ni10Mo10Ti5(Y2O3)1 (alloy B), W73Ni10Mo10Ti5(Y2O3)2 (alloy C) (all in wt%) by compaction at 500 MPa pressure for 5 min and conventional pressureless Ar injected sintering at 1500 °C for 2 h. The phase evolution, microstructure, thermal characteristics, mechanical and high temperature behavior of the mechanically alloyed powders and sintered alloys has been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS) and differential scanning calorimetry (DSC). Alloy C shows minimum crystallite size and maximum lattice strain, dislocation density of 18.6 nm, 0.54%, 36.71 × 1016/m2 respectively at 20 h of milling as compared to other alloys. The activation energy for recrystallization decreases with increase in Y2O3 dispersion. The residual stress also enhances with increased Y2O3 content. Alloy C exhibits improved relative sintered density, hardness and elongation of 92.1%, 7.22 GPa, 12.73% respectively and appreciable wear resistance, high temperature oxidation resistance at 1000 °C whereas maximum compressive strength of 1.91 GPa has been recorded in alloy B as compared to other alloys. Most interestingly the ductility also enhances with increase in Y2O3 dispersion.