Influence on the structural and magnetic properties of pre-alloyed gas-atomized Fe49Co49V2 powders during mechanical milling

The influence on the structural and magnetic properties of pre-alloyed gas-atomized Fe(49)Co(49)V(2 )powders during mechanical milling was investigated. The powders were mechanically milled for up to 45 h. The powders, before milling, were principally comprised of a-phase. No noticeable phase transformation was observed during mechanical milling of the pre-alloyed powders. Mechanical milling resulted in a gradual decrease in crystallite size to as low as similar to 10 nm, accompanied by an increase in lattice strain to similar to 1.2-1.5%. Mechanical milling led to an appreciable reduction in the particle size while the morphology of the milled powders appeared similar once the steady-state was attained. The lattice parameter of the nanostructured powders at steady-state was estimated as 0.2857 +/- 0.0004 nm. The saturation magnetization (Ms) of the nanostructured powders milled for similar to 45 h was similar to 211 +/- 1 Am-2/kg, and it decreased only by similar to 6% compared to that of the pre-alloyed gas-atomized powders before mechanical milling. The intrinsic coercivity (H-CI) of the pre-alloyed powders was estimated as similar to 1.4 +/- 1% kA/m. The H(CI )peaked to similar to 8.4 kA/m during the initial stages of milling and subsequently remained between similar to 6.5 kA/m to similar to 6 kA/ in, during the later stages of milling. As would be expected, the H-CI was strongly dependent on the crystallite size. The ferromagnetic exchange length of the nanostructured powders was estimated to be similar to 27 nm. The magnetic properties of nanostructured Fe49Co49V2 powders obtained by mechanical milling of pre-alloyed powders had relatively superior magnetic properties compared to the nanostructured powder obtained by mechanical alloying of the constituent elemental powders. (C) 2018 Elsevier B.V. All rights reserved.