# Investigation on the Impurity Removal Behavior During the Electron Beam Melting of V-Al Alloy

## TL;DR

This paper studies how impurities are removed during the melting of V-Al alloy using electron beams, finding that some impurities evaporate while others concentrate.

## Contribution

The study introduces a thermodynamic analysis of impurity removal behavior in V-Al alloy during electron beam melting.

## Key findings

- Impurities like Al, Fe, Co, Ni, Cr, and Ti are effectively removed due to high evaporation coefficients.
- Impurities like Si, Mo, Nb, and W increase in concentration due to low evaporation coefficients and enrichment effects.
- Carbon reacts with vanadium to form V2C, which is hard to remove due to its high melting point.

## Abstract

This study systematically investigated the behavior of impurity removal during the electron beam melting (EBM) process of V-Al alloy. Characterization techniques such as ICP, GDMS, SEM, EPMA, and TEM were used to analyze the composition content and microscopic element distribution of V-Al alloy and purified metal samples. Additionally, based on thermodynamic principles, the saturation vapor pressure and evaporation coefficients of impurity elements were calculated. The results indicate that the evaporation coefficients of Al, Fe, Co, Ni, Cr, and Ti exceed 1, enabling their effective removal during the melting process, thereby reducing their concentrations. In contrast, Si, Mo, Nb, and W exhibit evaporation coefficients significantly lower than 1, making their removal difficult. Instead, their concentrations increase due to the enrichment effect. Microstructural analysis reveals that Al migrates toward high-temperature regions, forming enrichment zones at the surface layer in contact with the electron beam. In contrast, Si, C, and O exhibit bidirectional migration characteristics, accumulating at both the upper and lower surfaces of the plate-shaped ingot. TEM observations indicate that some C reacts with V to form V2C, which has a higher melting point than vanadium, making further removal difficult.