Electrodeposition of iron-enriched nanocrystalline Fe-Ni alloy foil from chloride-sulfate solutions

Purpose - The purpose of this paper is to obtain iron-enriched Fe-Ni alloy foil on Ti substrates with good quality from a chloride-sulfate bath used in a normal DC plating mode. The effects of iron content on the hardness, surface morphology and microstructure of the foil were clarified. Design/methodology/approach - Fe-Ni alloy foil was prepared by electrodeposition in a chloride-sulfate based solution. The effects of current density, temperature, stirring rate and sodium propargyl sulfonate concentration on the iron contents of the Fe-Ni alloy foils were studied. The phase composition and surface morphology with various iron contents were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Cathodic polarization curves were used to evaluate the role of sodium propargyl sulfonate (PS). Findings - Nanocrystalline Fe-Ni alloy foil containing up to 64 wt. percent iron can be obtained from a chloride-sulfate based solution. The foil converts from a face-centered cubic (fcc) Fe3Ni2 phase to a mixture of fcc and body-centered cubic (bcc) Fe7Ni3 with increase in iron content from 55.0 wt. percent to 63.5 wt. percent. AFM studies revealed that the foil had a line grain structure with a roughness of 30 nm and grain size of 30 nm. With iron increasing to 63.5 wt., percent some islands appeared on the surface. This structure was related to the development of a (200) fiber texture in the BCC phase. Sodium propargyl sulfonate accelerates the discharge of nickel and inhibits the discharge of Fe. Practical implications - The foil has many industrial applications in the area of memory devices for computers, laser components and precise instruments. Originality/value - The paper presents a process to produce a foil with iron up to 64 wt. percent from a chloride-sulfate based solution used in normal DC mode. The dependence of microstructure and surface morphology on iron contents also is presented. Until now, there has been little research or reports on this subject.