Influence of the preparation conditions on the microstructure of electrodeposited nanocrystalline Ni–Mo alloys

Abstract

Structural parameters of electrodeposited Ni–Mo alloys with Mo concentrations up to 6.1 at% were determined by X-ray line profile analysis as a function of various deposition parameters such as pH, Mo(VI) concentration of the bath and deposition current density. In addition to crystallite size, parameters describing the defect structure, such as twin fault probability and dislocation density, were also determined. These microstructural parameters cannot be obtained using classical evaluation methods of X-ray diffractograms. It was found that the crystallite size decreased while the defect density increased with increasing Mo content of the deposits in a sample series where the single variable was the Mo(VI) concentration of the bath. A similar trend was found when the current density was varied for a sample series processed with constant Mo(VI) concentration. However, the comparison of the different sample series revealed that the defect structure is a result of a complex interplay of all deposition conditions and is not solely related to the Mo content of the deposits. The influence of the electrodeposition parameters on the defect structure is discussed in detail.