Electrodeposition and Thermal Stability of Re₆₀Ni₄₀ Amorphous Alloy

Abstract

Re₆₀Ni₄₀ alloy was electrodeposited galvanostatically from aqueous solution containing 34 mM ammonium perrhenate, 124 mM nickel sulfamate tetrahydrate and 343 mM citric acid in a three-electrode cell system at bath temperature of 70°C. The deposition mechanisms of the alloy were discussed by cyclic voltammetry and cathodic potentiodynamic tests. Microstructure and morphology of surface and fracture surface of the alloy were examined by ESEM. The phase and chemical composition were tested by XRD and EDS, respectively. The thermal stability of the alloy was estimated by DSC. The results show that electrodeposition of Re-Ni alloy is an anomalous deposition. Many cracks were present on the surface and fracture surface of the alloy. The fracture surface of the alloy exhibited both a fibrous structure and a laminar structure. The chemical composition distribution in the alloy was uniform. The alloy adhered well to the substrate with no evidence of delamination. Re₆₀Ni₄₀ alloy was composed of an amorphous structure, and the deposition rate was about 16.5 µm h⁻¹. The average roughness R_a and R_q of the alloy surface were 123 ± 13 and 158 ± 17 nm, respectively. After DSC test, the amorphous Re₆₀Ni₄₀ alloy exhibited a good thermal stability from 25°C to 550°C.