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

TL;DR

This study investigates how nitrogen ion implantation affects the microstructure and chemical composition of a biodegradable Zn-0.8Mg-0.2Sr alloy, revealing nano/micro-porous layer formation and increased magnesium content.

Contribution

It provides new insights into the microstructural changes and chemical composition alterations induced by nitrogen ion implantation in biodegradable zinc alloys.

Findings

Formation of nano/micro-porous layers up to 400 nm thick.

Significant increase in magnesium content from 0.8 to 15 wt%.

Presence of nitrogen in zinc confirmed by GD-OES.

Abstract

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 17x10^17 ions/cm^2 resulted in the oversaturation of pure Zn and Mg2Zn11 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 pore structures. A limited formation of MgO and Mg3N2 was observed on the alloy surface, although the overall presence of Mg significantly increased from 0.8 to 15 wt.%. This increase was caused by the decomposition of the Mg2Zn11 phase during the process and subsequent diffusion of Mg toward the surface. The absence of Zn3N2 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 out to the complex nature of the process and highlights other promising directions for future research.