Micromechanical and biodegradation properties of a rapidly solidified Mg-1.3Zn alloy with gradient microstructure

• Vacuum arc melting enables the study of phase formation in Mg-Zn alloys. • Zn-segregated areas in Mg-Zn alloys relate to higher corrosion resistance in DMEM. • Correlative microscopy identified hydroxyapatite, Mg(OH) 2 and CaCO 3 . • Gradient microstructure can be effectively used for rapid alloy evaluation. The development of novel magnesium alloys for resorbable implants is a financially demanding and time-consuming process. To mitigate the costs of property screening using multiple samples, a framework employing a single sample with a gradient microstructure was used. Rapidly solidified Mg-1.3Zn alloy, micro-alloyed with manganese, was obtained through vacuum arc melting. The sample was examined via correlative microscopy, electron backscatter diffraction and characterized by nanoindentation. Furthermore, ageing in air at 180 °C was performed to study the evolution of the secondary phases and Zn grain boundary segregation. Ageing-induced Zn segregation near the boundaries led to an increase in nanohardness to 749 ± 83 MPa, compared to the inner grain value of 639 ± 72 MPa. A detailed analysis of corrosion product formation was carried out after biodegradation in Dulbecco’s Modified Eagle Medium to shed light on the different degradation phenomena and the role of Zn grain boundary segregation in corrosion localization. Overall, the correlative microscopy highlighted the important influence of Zn segregation on the microstructure and corrosion properties of diluted Mg-Zn alloys. These results, together with the data connected to the observed Mg(OH) 2 , CaCO 3 and hydroxyapatite, show the effectiveness of this approach for the initial screening of biomedical alloys.