Tailoring Single- and Dual-Phase Layered Structures in Supersaturated Solid Solution Nanocrystalline Co-Cu Alloys Via Pulsed Electrodeposition for the Development of High-Strength Complex Micro-Components

K. Pratama; C. Tian; A. Sharma; M. Watroba; J. Gubicza; B. Dilasari; J. Schwiedrzik; J. Michler

Ssrn (2023)

This paper shows a new approach to tailoring microstructure from a homogeneous to a dual-phase layered structure in nanocrystalline (NC) Co-Cu alloys prepared by pulsed electrodeposition (PED) through variation in the concentration of sodium dodecyl sulfate (SDS) in the electrolyte. The increasing concentration of SDS played a crucial role in improving surface quality and stabilizing a homogeneous solid solution Co-Cu structure. On the other hand, the opposite approach led to the formation of a dual-phase alloy in the form of nanometer scale of multilayer structure consisting of the primary and the secondary solid solution Co-Cu differing in 10-15 at.% Cu. It was discussed that the formation of secondary phase layer is not influenced by the displacement reaction of Co with Cu2+ ions during the off-time period nor post-deposition room temperature atomic diffusion in NC materials. Instead, the secondary phase layers may be developed due to the periodical rising concentration of Cu2+ ions within electrical double layer (EDL) during deposition, in which a combination of non-ideal EDL discharge and low SDS concentration have a strong contribution for this mechanism. The mechanical properties of selected single- and dual-phase NC Co-Cu alloys were investigated through micro-pillar compression, revealing that a combination of a high yield strength and an elevated strain hardening can be achieved in NC materials through a combined strengthening from solid solution and nanotwin structures. A superior surface quality, a high mechanical strength, and a tunable microstructure are interesting characteristic for development of this alloy in template-assisted electrochemical deposition (TAED) of micro-components such as micro-pillar and micro-gear.

DOI: https://doi.org/10.2139/ssrn.4536189