XRD Characterization of Microstructural Evolution During Mechanical Alloying of W-20 wt%Mo

The present paper reports a study on the microstructural evolution during mechanical alloying of W-20wt%Mo using XRD line profile analysis. The W-20wt%Mo powder blends were ball milled using Fritsch Pulverisette P-5 high energy ball mill for varying milling time (0, 5, 10, 15, 20 h) at 300 rpm with 10:1 and 2:1 ball to powder weight ratio. The crystallite size and lattice strain were calculated using Langford method (‘average’ Williamson-Hall Plot). The precision lattice parameter calculation was done using Nelson–Riley method. The effect of milling on alloying behaviour has been investigated using change in relative integrated intensity ratios (IMo/IW/W(Mo)) of (211) XRD peak. There was complete alloying in case of 10:1 ball to powder weight ratio, whereas half of the Mo (~10 % Mo) was alloyed with 2:1 ball to powder weight ratio. The paper also discusses the applicability of the criteria based on lattice parameter change (peak shift) for alloying behaviour during mechanical milling.