Enhanced Plasticity and Corrosion Resistance in Mg-Zn-Ca-Cu Amorphous Alloy Composite via Plasma Electrolytic Oxidation Treatment

Shuangshuang Chen,Peidi Song,Haodi Li,Qingling Zeng,Xierong Zeng

doi:10.3390/met12020300

Shuangshuang Chen, Peidi Song + Show 3 more

Open Access

https://doi.org/10.3390/met12020300

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Journal: Metals	Publication Date: Feb 9, 2022
Citations: 4	License type: CC BY 4.0

Affiliation: Anhui University of Technology, Shenzhen University

Abstract

In this study, a dendrite-reinforced Mg-based amorphous alloy composite was prepared through an in situ precipitation strategy. After plasma electrolytic oxidation (PEO) treatment, the Mg85.1Zn12.7Ca2Cu0.2 amorphous alloy composite exhibited enhanced plasticity and corrosion resistance in a simulated body fluid solution (SBF). The PEO-treated composite showed a significant plastic strain of 10.5 ± 1.1%, as well as outstanding strain-hardening behavior. The enhancement of plasticity may be attributed to the in-situ formed coating, which can not only serve as a propagation barrier for shear bands but can also introduce nucleation sites in the bands as a result of stress mismatch and compositional heterogeneity. The corrosion density in the SBF decreased by three orders compared with the composite substrate. The spontaneous formation of apatite on the porous layer demonstrated that the prepared PEO coating has high bioactivity. The current work may provide a fundamental basis for developing biomedical Mg-based alloys with excellent comprehensive mechanical properties and corrosion resistance.

Highlights

In recent years, Mg and its alloys have attracted increasing attention as metallic implants owing to their good biodegradability, biocompatibility and elastic modulus similar to natural bone [1,2,3]
Deformation in monolithic amorphous alloys is generally localized within shear bands that may instantly propagate across the whole specimen due to strain softening and/or thermal softening, which leads to final catastrophic fractures
The improvement inplasticity may be attributed to the in situ formed coating, which can serve as a propagation barrier for shear bands but can introduce nucleation sites for the bands resulting from stress mismatch and compositional heterogeneity

Summary

Introduction

Mg and its alloys have attracted increasing attention as metallic implants owing to their good biodegradability, biocompatibility and elastic modulus similar to natural bone [1,2,3]. Despite their various advantages, these materials face several challenging obstructions in that they usually present humble mechanical strength and a rapid corrosion rate. Deformation in monolithic amorphous alloys is generally localized within shear bands that may instantly propagate across the whole specimen due to strain softening and/or thermal softening, which leads to final catastrophic fractures To surmount this critical shortcoming, many efforts have been made in the design of composite structures consisting of an amorphous matrix and a second ductile crystalline phase [12,13]. Compared with monolithic Mg-based amorphous alloys, the corrosion resistance of such composites is inevitably reduced since the interface between the crystalline phase and the glassy matrix often serves as the core of pitting corrosion [14]

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