Combined effect of Ni and nano-Y2O3 addition on microstructure, mechanical and high temperature behavior of mechanically alloyed W-Mo

Nanostructured tungsten (W) based alloys with the nominal compositions of W70Mo30 (alloy A), W50Mo50 (alloy B), and 1.0 wt.% nano-Y2O3 dispersed W79Ni10Mo10 (alloy C) (all in wt.%) have been synthesized by mechanical alloying followed by compaction at 0.50, 0.75 and 1 GPa pressure for 5 mins and conventional sintering at 1500 degrees C for 2 h in Ar atmosphere. The microstructure, evolution of phases and thermal behavior of milled powders and consolidated products has been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), High resolution transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS) and differential scanning calorimetry (DSC). Minimum crystallite size of 29.4 nm and maximum lattice strain and dislocation density of 0.51% and 18.93 (10(16)/m(2)) respectively has been achieved in alloy C at 20 h of milling. Addition of nano-Y2O3 reduces the activation energy for recrystallization of W based alloys. Alloy C compacted at 1 GPa pressure shows enhanced sintered density, hardness, compressive strength and elongation of 95.2%, 9.12 GPa, 1.51 GPa, 19.5% respectively as well as superior wear resistance and oxidation resistance (at 1000 degrees C) as compared to other W-Mo alloys. (C) 2016 Elsevier Ltd. All rights reserved.