Study of microstructure, thermodynamic and powder properties of nano Y2O3, TiO2, ZrO2 dispersed W–Ni–Nb–Mo–Zr alloys

Abstract

The paper reports the synthesis of 1 wt% nano Y2O3 (Sa), TiO2 (Sb), ZrO2 (Sc) separately dispersed in W78Ni10Nb5Mo5Zr1 (in wt. %) alloys by mechanical alloying. X-ray diffraction (XRD) analysis shows that Zr with Y2O3 addition has maximum refinement in crystallite size (9.23 nm) and enhancement in lattice strain. High-resolution Transmission electron microscopy (HRTEM) and Selected area diffraction (SAD) studies indicate the development of nanocrystallites at 20 h of milling of oxide dispersion strengthened (ODS) W alloys. Thermodynamic analysis shows marginally negative enthalpy of mixing of W–Ni–Nb–Mo–Zr alloy. The XRD data and thermodynamic analysis reveal that Ni, Mo, Nb, Zr can form solid solutions with W. The average particle size measured from Dynamic Light Scattering is minimum for alloy Sa (0.9 ± 0.02 μm). The Carr's index, Hausner ratio, and angle of repose (AOR) value suggest that alloy Sa shows excellent flowability and is significant to achieve enhanced die filling and consolidation of powders.