# Hardness Changes Due to the Morphological Evolution of Microstructural Phases in an As-Solidified Zn-Fe Alloy

## TL;DR

This paper studies how the microstructure of a Zn-Fe alloy affects its hardness, finding that particle spacing has less impact than particle and matrix morphology.

## Contribution

The study reveals that hardness in Zn-Fe alloys is more influenced by the morphology of microstructural phases than by their refinement.

## Key findings

- The Zn-2wt.%Fe alloy microstructure consists of a Zn-rich matrix and FeZn13 intermetallic particles.
- Hardness is more dependent on the morphology of FeZn13 particles and the Zn-rich matrix than on particle spacing.
- Four distinct microstructural patterns were observed based on solidification thermal conditions.

## Abstract

Zn-Fe alloys are gaining attention for their use as bioabsorbable implants, and their development requires a deeper understanding of the processing–microstructure–property relationships. This study aimed to analyze the influence of microstructural features on the hardness of a Zn-2 wt.%Fe alloy. To achieve this, a casting was fabricated using directional solidification, and samples that experienced various cooling conditions were extracted from it. The results show that the microstructure of the investigated alloy was composed of a Zn-rich phase (matrix) and FeZn13 intermetallic particles. Four different morphological patterns of the microstructure could be formed, depending on the thermal conditions during solidification. For each of these patterns, a reduction in the spacing between FeZn13 particles, a parameter representing the degree of microstructural refinement, did not lead to a considerable increase in the hardness of the Zn-2wt.%Fe alloy. Hardness was shown to be more dependent on the morphology of the FeZn13 intermetallics and Zn-rich matrix than on the degree of refinement of these microstructural phases. Therefore, the present research provides valuable insights into the development of enhanced Zn-Fe alloys by demonstrating how microstructural features can affect their properties, particularly in terms of hardness and morphologies of the microstructural phases.