title: Fabrication and characterization of a biodegradable Mg-2Zn-0.5Ca/1β-TCP composite.
abstract: A biodegradable magnesium matrix and beta-tricalcium phosphate (β-TCP) particles reinforced composite Mg-2Zn-0.5Ca/1beta-TCP (wt.%) was fabricated for biomedical applications by the novel route of combined high shear solidification (HSS) and equal channel angular extrusion (ECAE). The as-cast composite obtained by HSS showed a fine and equiaxed grain structure with globally uniformly distributed β-TCP particles in aggregates of 2-25 μm in size. The ECAE processing at 300 °C resulted in further microstructural refinement and the improvement of β-TCP particle distribution. During ECAE, the β-TCP aggregates were broken into smaller ones or individual particles, forming a dispersion in the matrix. Such fabricated composite exhibited enhanced hardness and in vitro corrosion resistance. The enhanced hardness was attributed to both the addition of β-TCP particles and grain refinement while the development of a Ca-P rich surface layer from β-TCP during corrosion was responsible for the improvement in corrosion resistance. The composite was characterized in terms of microstructural evolution during fabrication, mechanical properties and electrochemical performance during polarization and immersion tests in a simulated body fluid. Discussions are made on the benefits of both HSS and ECAE and the mechanisms responsible for the enhanced corrosion resistance.
authors.affiliation: BCAST, Brunel University, Uxbridge, Middlesex UB8 3PH, UK. Electronic address: yan.huang@brunel.ac.uk.
authors.forename: Yan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
authors.forename: Debao
authors.initials: D
authors.lastname: Liu
authors.affiliation: Experimental Techniques Centre, Brunel University, Uxbridge, Middlesex UB8 3PH, UK.
authors.forename: Lorna
authors.initials: L
authors.lastname: Anguilano
authors.affiliation: School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
authors.forename: Chen
authors.initials: C
authors.lastname: You
authors.affiliation: School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China.
authors.forename: Minfang
authors.initials: M
authors.lastname: Chen
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002130:Calcium Phosphates / Q000737:chemistry*; D003343:Corrosion; D006244:Hardness; D006358:Hot Temperature; D008274:Magnesium / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; C485817:beta-tricalcium phosphate; D008274:Magnesium
keywords: ECAE; High shear solidification; In vitro corrosion; MMCs; Magnesium; β-Tricalcium phosphate