Influence of current density on crystalline structure and magnetic properties of electrodeposited Co-rich CoNiW alloys |
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Authors: | A.M.P. Sakita E.C. Passamani H. Kumar D.R. Cornejo C.S. Fugivara R.D. Noce A.V. Benedetti |
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Affiliation: | 1. Instituto de Química, Univ. Estadual Paulista-UNESP, 14800-900 Araraquara, SP, Brazil;2. Departamento de Física, Univ. Federal do Espírito Santo, Vitória 29075-910, ES, Brazil;3. Instituto de Física, Univ. São Paulo, USP, 05508-090 São Paulo, SP, Brazil |
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Abstract: | The influence of current density, at the interval 5–100 mA cm−2, on the structural and magnetic properties of electrodeposited (Co100−xNix)100−yWy alloys (x = 23–33.5 at. % Ni, y = 1.7–7.3 at. % W) was studied from a glycine-containing bath. W-content decreases with the increase of the current density magnitude. X-ray data have shown stabilization of hexagonal close packed, face centered cubic or a mixture of these structures by modulating the applied cathodic current density, for values lower than 50 mA cm−2. Two structural phase transitions were observed: one from hexagonal close packed to face centered cubic structural transition occurring for a current density of 20 mA cm−2, and another one, from cubic crystalline phase to amorphous state, which happens for values higher than 50 mA cm−2. These structural phase transitions seem to be associated with the W-content as well as average crystalline grain sizes that reduce with increasing the current density value. The grain size effect may explain the face centered cubic stabilization in Co-rich CoNiW alloys, which was initially assumed to be basically due to H-adsorption/incorporation. Magnetic properties of Co-rich CoNiW alloys are strongly modified by the current density value; as a result of the changes on the W-content and their structural properties. |
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Keywords: | Alloys Magnetic materials Chemical synthesis Electron microscopy Magnetic properties |
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