Fabrication and characterization of nano-Cr2O3 dispersed mechanically alloyed and conventional sintered W-Zr alloys

Abstract

Tungsten based alloys with stoichiometric composition of W98.5Zr0.5(Cr2O3)1 (alloy A), W97.5Zr00.5(Cr2O3)2 (alloy B) and W98Zr1(Cr2O3)1 (alloy C) (all in weight %) were synthesized through mechanical alloying (MA) for 20 h followed by conventional sintering at 1500 °C for 2 h in argon atmosphere. The milled powders and consolidated alloys has been investigated using X-ray diffraction (XRD), Particle size analyzer, Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Elemental mapping (EM). Minimum crystallite size of 11.81 nm and maximum lattice strain and dislocation density of 0.44% and 47.98 × 1016/m2 respectively were observed in alloy A at 20 h milling. Lattice parameter of alloys A through C increases upto 5 h further decreases past 5 h of milling. Excellent powder flowability was found in alloy A with minimum angle of repose (°) α = 25.029° at 20 h mechanically milled powder. Higher dispersion stability noticed in alloy C with zeta potential value −15.5 mV among all 20 h milled powder in pH2.4. The minimum average particle size of 321.6 nm was found in alloy C at 20 h milled powder on dilution with water has been measured using Dynamic light scattering (DLS). ZrCr2 intermetallics in the sintered alloys evident of both solid phase and liquid phase sintering. Maximum Sinterability and hardness of 91.46% and 13.613 GPa respectively observed in alloy A due to its fine crystallite size.