On the state of W in electrodeposited Ni-W alloys

We have derived an expression for the theoretical dependence of the Ni-W fcc phase lattice parameter on the atomic fraction of W, in a solid solution. This parameter was used to compare the actual quantity of W, in a solid solution of electrode posited Ni-W alloys, with the value determined by EDX. It has been shown that not all of the W determined by EDX was present as a solute in the Ni-W fcc phase. The incorporation of tungstates prevailed at lower pH, while the presence of citric complexes dominated at higher pH values. This conclusion was based on the XRD phase analysis of electrodeposited alloys that were annealed in hydrogen or argon atmospheres at 1000 degrees C. The XRD data correlated well with the morphology results obtained via AFM. The incorporation of tungstates or citric complexes seems to be characteristic of the electrodeposited Ni-W alloys. (C) 2008 Elsevier Ltd. All rights reserved.