The influence of nitrogen ion implantation on the microstructure and chemical composition of a thin layer on the biodegradable Zn-0.8Mg-0.2Sr substrate

In this research, the influence of the N + ion implantation process on the microstructure of a biodegradable Zn-0.8Mg-0.2Sr alloy was investigated using various experimental techniques. Microscopic analysis revealed that a fluence of 17·10 17 ions/cm² resulted in the oversaturation of pure Zn and Mg 2 Zn 11 surfaces, leading to the formation of nano/micro-porous layers up to 400 nm thick. The behavior of the Zn-0.8Mg-0.2Sr alloy was observed to be similar to that of the individual pure phases, albeit without the creation of open pore structures. A limited formation of MgO and Mg 3 N 2 was observed on the alloy surface, although the overall surface presence of Mg significantly increased from 0.8 to 15 wt. %. This increase was caused by the decomposition of the Mg 2 Zn 11 phase during the process and the subsequent diffusion of Mg toward the surface. The absence of Zn 3 N 2 within the samples could be explained by the thermodynamic instability and low Zn-N affinity. Despite the absence of zinc nitride, GD-OES confirmed 10 at. % of nitrogen in the pure zinc, suggesting a possible accommodation of N atoms in the interstitial positions. This study points to the complex nature of the process and highlights other promising directions for future research.