Investigation into the structure of electrodeposited nickel-phosphorus alloy deposits

This paper presents a study into the structure of Ni-P deposits containing 1.15-15.43 mass% P using X-ray diffraction. The coatings were deposited from electrolytes containing both phosphorous and phosphoric acids using conventional direct current. Samples obtained by electroless deposition were also examined for comparative purposes. The effects of composition on crystallite/grain size have been determined quantitatively using an X-ray diffraction line broadening technique and the formation of X-ray amorphous structures have also been followed using X-ray diffraction. The development of the amorphous phase, however, was found to be sensitive to crystallographic orientation. At amorphous contents above 70%, the crystalline nickel phase was associated only with (111)/(222) orientations parallel to the surface of the deposits. This appeared to result from a decrease in the growth rate of other orientations, e.g. (200), relative to the (111) orientation.