Tensile strength and elongation of nanocrystalline Fe-Co-Ni ternary alloy films electrodeposited from acidic aqueous solution

Abstract Electrodeposited Fe-Co-Ni alloy thick films with a thickness of approximately 200 μm were mechanically exfoliated from a metallic titanium cathode with a dumbbell shape to examine the crystal orientation, microhardness and tensile strength. The electrodeposited Fe-Co-Ni alloy thick films were composed from a solid solution γ phase and the average crystallite size was around tens of nanometers. The microhardness, tensile strength and elongation achieved up to 517 HV, 1.6 GPa and 4.54%, respectively. Especially, the elongation increased with increasing the mixing entropy of electrodeposited Fe-Co-Ni alloy thick films. These improvement in mechanical properties can be explained by the formation of a solid solution γ phase with nanocrystalline structure.