The microstructure and internal stress of Fe–Ni nanocrystalline alloys electrodeposited without a stress-reliever

Microstructural heterogeneity in the electrodeposited Ni: insights from growth modes

Microstructures of electrodeposited Ni were studied from the perspective of growth modes during electrodeposition. The electrodeposited Ni had a heterogeneous microstructure composed of nanocrystalline- and microcrystalline-grains. Electron backscatter diffraction analyses showed that nanocrystalline- and microcrystalline-grains were preferentially oriented to specific planes. Secondary ion mass spectrometry also revealed that coarse-grained regions had higher S content than that of finer-grained regions. Hence, microstructural heterogeneity in electrodeposited Ni is reflected by the overlap of inhibited and free growth modes. Our discussion surrounding microstructural heterogeneity also provides insight into other electrodeposited nanocrystalline systems.

AN INVESTIGATION ON THE EFFECT OF ELECTROCHEMICAL ADSORBATES ON PROPERTIES OF ELECTRODEPOSITED NANOCRYSTALLINE Fe–Ni ALLOYS

Iron–Nickel nanocrystalline alloys were electrodeposited from a simple chloride bath using different current densities. The composition and grain size of deposited alloys were in the range of 29–42% Ni and 8–11 nm, respectively. The alloy deposited at lower current density showed higher microhardness, which is most probably due to its higher Fe content and lower grain size. EIS measurements showed that the iron hydroxide species can be formed and adsorbed onto the cathode surface during the deposition. Such species showed an inhibitive effect not only on Ni ion reduction but also on grain growth. By increasing the deposition current density, the adsorption tendency of iron hydroxide was reduced which caused an increase in grain size and Ni percentage of the alloy produced.

Growth, Crystal Structure and Stability of Ag-Ni/Cu Films

AgxNi1-x (x=0.0-1.0) films were grown on Cu substrates by electrodeposition method. The films were found to be a nanocrystalline mixture of pure silver and nickel. The grain sizes were determined by X-ray diffraction and electron microscopy techniques. The minimal value was 3.3 m for the alloy with 70 wt% concentration of Ni. The stability of the grown films upon heating in ir and in vacuum was examined. An increase in the grain size was found to begin at 150°C.