A Heterogeneously structured Mg-Zn laminate alloy for gradient degradation behavior.

Abstract

In order to advance the application of magnesium alloys as short-term implants, there is a growing need to further regulate the temporal evolution of their degradation rates to better align with clinical requirements. However, it is difficult for conventional bulk magnesium alloys. To address this limitation, this study developed a layered Mg-Mg2Zn-Mg4Zn-Mg6Zn-Mg4Zn-Mg2Zn-Mg laminate alloy (named as MZM in this study) based on a heterogeneous gradient structure (HGS) strategy, which created gradient heterogeneity in alloy composition, recrystallization degree, product layer, and interfacial features along the normal direction (ND), thereby establishing a synergistic interplay to achieve a progressively increasing degradation profile. The MZM was fabricated by stacking a series of Mg-Zn alloys with a symmetric gradient in Zn concentration (0, 2, 4, 6, 4, 2, 0 wt%) through two-pass hot rolling at nearly 400 °C, followed by quenching. The MZM alloy exhibited a low <i>in vivo</i> degradation rate of 0.054 ± 0.0062 mm/year, followed by an increasing rate (0.180 ± 0.003 mm/year), all within a biosafe range. This study offers important insights and provides a scientific basis for the development of next-generation biodegradable metallic materials.