Microstructure, tensile properties, and corrosion resistance of extruded Mg-1Bi-1Zn alloy: The influence of minor Ca addition

The role of minor Ca addition on microstructure, tensile properties, and corrosion resistance of an extruded Mg-1Bi-1Zn alloy was investigated. The results indicated that with the addition of 0.6 wt% Ca, the grain structure became more homogeneous and the formation of a new ternary phase Mg2Bi2Ca could be confirmed. An increase in the fraction of dynamic recrystallized grains from 76.4% to 92.9% was achieved. The texture intensity increased from 6.83 to 7.96, which could be ascribed to the increase in the fraction of relatively coarse grains. The variation in microstructural characteristics resulted in both tensile properties (yield strength from 173 MPa to 215 MPa, and elongation from 22.3% to 27.1%) and corrosion resistance (P-i from 0.41 mm/a to 0.32 mm/a) improved significantly in the present Mg-1Bi-1Zn-0.6Ca alloy, which exhibited potential to be developed as a biodegradable implant material. Moreover, the corrosion mode of studied alloys changed from pitting dominated corrosion to filiform dominated corrosion through the minor Ca addition, revealing that a denser protective layer was formed in the Ca-added alloy and thus the corrosion resistance was improved. (C) 2019 Elsevier B.V. All rights reserved.