Preparation of Fe-Co-Ni Ternary Alloys with Electrodeposition

Electrodeposition of Fe-Co-Ni ternary alloys was performed in a chloride-sulphate-tartaric acid medium. The influences of electroplating parameters such as current density, temperature, pH value and electrolyte composition on depositing rate, compositions of Fe-Co-Ni deposits and electrodepositing behavior on titanium substrate were investigated. The composition, morphology and the microstructure of deposits were analyzed by EDS, SEM and XRD, respectively. The results indicated that the optimum conditions for obtaining Co-rich Fe-Co-Ni alloys were current density of 4 A/dm2, temperature of 40 °C, pH of 2.3-3.2, tartaric acid concentration of 8-12 g/l, Co2+ / Ni 2+ molar ratio of 0.26-0.4. The codeposition of Fe-Co-Ni alloy is anomalous; namely Fe is more easily deposited than Co, and Co is easily deposited than Ni. However, the deposition order of Fe and Co is affected by temperature and Co2+ / Ni 2+ ratio. The Fe-Co-Ni ternary alloys with 15.62-20.56% of Fe, 43.84-61.93% of Co, 22.45%-40.05% of Ni were bright and super toughness with low residual stress. The SEM showed that fine-grain, smooth and compact Fe-Co-Ni alloy deposits were obtained. The crystallographic structure of the deposit was the bcc solid solution.