Article ID Journal Published Year Pages File Type
7999081 Journal of Alloys and Compounds 2015 7 Pages PDF
Abstract
The effects of isochronal annealing on microstructure and magnetic properties of Co40Fe22Ta8B30 powders with a large content of amorphous phase produced by mechanical alloying have been investigated. The differential scanning calorimetry (DSC) results indicate that the synthesized powders exhibit a huge exothermic reaction before the crystallization temperature corresponding to structural relaxation of amorphous phase. Furthermore, the structural evolution of the powders upon isochronal heating has been investigated by in-situ X-ray diffraction (XRD) using high energy synchrotron radiation. The occurrence of an irreversible structural relaxation is confirmed by significant changes in position of the first and second diffuse maxima of the total structure factor S(Q) upon isochronal heating-cooling cycles. Moreover, analysis of the reduced pair distribution functions (PDFs) yields a volume shrinkage of about 1.5% after annealing due to annihilation of the excess free volume generated upon milling. The isochronal annealing significantly affects the magnetic properties of the powders through decreasing the saturation magnetization and coercivity. The correlation between structural relaxation and magnetic properties of the powders is discussed.
Related Topics
Physical Sciences and Engineering Materials Science Metals and Alloys
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