Long-term in vitro corrosion behavior of Zn-3Ag and Zn-3Ag-0.5Mg alloys considered for biodegradable implant applications. (January 2022)

• Record Type: Journal Article
• Authors: Wątroba, Maria; Mech, Krzysztof; Bednarczyk, Wiktor; Kawałko, Jakub; Marciszko-Wiąckowska, Marianna; Marzec, Mateusz; Shepherd, Duncan E.T.; Bała, Piotr
• Is Part Of: Materials & design. Volume 213(2022)
• Publication Date: 2022-01
• Subjects: Zn alloys -- Microstructure -- Mechanical properties -- Biodegradation -- Galvanic corrosion -- Electrochemical measurements; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2021.110289
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: Additions of Ag and Mg provided grain refinement and multiphase microstructure. Investigated Zn alloys degraded mainly via intergranular and micro galvanic corrosion. Refined Zn grains and evenly distributed small precipitates provided uniform corrosion. Precipitates of the ε-Zn3 Ag phase corroded slower than Zn and remained in the pits. The corrosion rate of the Zn-3Ag-0.5Mg alloy after 180-day immersion was 21.6 µm/year. Abstract: In this paper, Zn-3Ag and Zn-3Ag-0.5Mg alloys were studied in terms of applicability as biodegradable implant materials. The performed tensile, compression and bending tests indicate a high strengthening effect induced by the Ag and Mg additions, additionally resulting in grain size refinement. It was shown that sustaining plastic strain during deformation depends on the applied stress causing asymmetric mechanical behavior of the tested Zn-based materials. Electrochemical measurements and immersion tests in Hanks' solution lasting up to 180 days revealed that Ag and Mg contribute to the change of the Zn matrix's open circuit potential and the formation of micro-galvanic cells between the Zn grains and precipitates. The fine-grained microstructure and evenly distributed small precipitates led to uniform corrosion occurring via pit formation on the corroded surface due to intergranular and micro-galvanic corrosion mechanisms. The corrosion rate of the Zn-3Ag-0.5Mg alloy after 180 days was almost twice that of pure Zn and the Zn-3Ag alloy.