Materials Chemistry and Physics, Vol.141, No.1, 576-581, 2013
Influence of current density on crystalline structure and magnetic properties of electrodeposited Co-rich CoNiW alloys
The influence of current density, at the interval 5-100 mA cm(-2), on the structural and magnetic properties of electrodeposited (Co100-xNix)(100-y)W-y 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. (C) 2013 Elsevier B.V. All rights reserved.