Three-dimensional analysis of the microstructure and bio-corrosion of Mg–Zn and Mg–Zn–Ca alloys

• Multi-scale tomography was used to characterise the morphology and distribution of secondary phases in Mg alloys.
• The development of localized corrosion was investigated using tomography.
• An improved understanding of the microstructure and corrosion was achieved using Micro-CT tomography.

The effects of the morphology and the distribution of secondary phases on the bio-corrosion properties of magnesium (Mg) alloys are significant. Focused Ion Beam (FIB) tomography and Micro X-Ray computed tomography (Micro-CT) have been used to characterise the morphology and distribution of (α-Mg + MgZn) and (α-Mg + Ca2 + Mg6 + Zn3) eutectic phase mixtures in as-cast Mg–3Zn and Mg–3Zn–0.3Ca alloys, respectively. There were two different 3D distributions: (i) an interconnected network and (ii) individual spheres. The tomography informed our understanding of the relationship between the distribution of secondary phases and the development of localized corrosion in magnesium alloys.