# Microstructure-Property Regulation in a Large-Size Mg-9.4Gd-5.8Y-1Zn-0.5Zr Alloy by Differential Phase Electromagnetic Semi-Continuous Casting and Homogenization

## TL;DR

A new casting method improves the structure and properties of a magnesium alloy, leading to better strength and flexibility.

## Contribution

A novel semi-continuous casting method with electromagnetic vibration is introduced to enhance microstructural homogeneity in a magnesium alloy.

## Key findings

- Grain sizes were uniformly 117–130 µm with low elemental segregation (<3%) of Gd and Y.
- Homogenization at 520°C for 5 hours dissolved eutectic phases and improved alloy properties.
- The alloy achieved a tensile strength of 208.4 MPa and elongation of 24.4%.

## Abstract

Based on a novel semi-continuous casting mold with independent primary cooling regulation, a large-size Mg-9.4Gd-5.8Y-1Zn-0.5Zr alloy billet (Ø330 mm) was successfully fabricated via differential phase electromagnetic vibration casting. This process significantly improved microstructural homogeneity, with grain sizes ranging from 117 µm to 130 µm across the billet and elemental segregation of Gd and Y below 3%. Homogenization at 520 °C for 5 h effectively dissolved grain boundary eutectic phases; promoted diffusion of Gd, Y, and Zn into the α-Mg matrix; and stimulated the precipitation of fine LPSO lamellae. These microstructural improvements resulted in an excellent tensile strength of 208.4 MPa and elongation of 24.4%, demonstrating an optimal strength–ductility balance achieved through precise thermal processing.