title: Effects of secondary phase and grain size on the corrosion of biodegradable Mg-Zn-Ca alloys.
abstract: The bio-corrosion behaviour of Mg-3Zn-0.3Ca (wt.%) alloy in simulated body fluid (SBF) at 37°C has been investigated using immersion testing and electrochemical measurements. Heat treatment has been used to alter the grain size and secondary phase volume fraction; the effects of these on the bio-corrosion behaviour of the alloy were then determined. The as-cast sample has the highest bio-corrosion rate due to micro-galvanic corrosion between the eutectic product (Mg+Ca2Mg6Zn3) and the surrounding magnesium matrix. The bio-corrosion resistance of the alloy can be improved by heat treatment. The volume fraction of secondary phases and grain size are both key factors controlling the bio-corrosion rate of the alloy. The bio-corrosion rate increases with volume fraction of secondary phase. When this is lower than 0.8%, the dependence of bio-corrosion rate becomes noticeable: large grains corrode more quickly.
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: Y
authors.initials: Y
authors.lastname: Lu
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: A R
authors.initials: AR
authors.lastname: Bradshaw
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: Y L
authors.initials: YL
authors.lastname: Chiu
authors.affiliation: School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: I P
authors.initials: IP
authors.lastname: Jones
mesh_terms: D020341:Absorbable Implants; D000497:Alloys / Q000737:chemistry*; D001826:Body Fluids / Q000737:chemistry; D002118:Calcium / Q000737:chemistry*; D003343:Corrosion; D008274:Magnesium / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D000497:Alloys; D008274:Magnesium; D015032:Zinc; D002118:Calcium
keywords: Degradation; Heat treatment; Mg–Zn–Ca; Microstructure