# Microstructure and thermal properties of unalloyed tungsten deposited by Wire + Arc Additive Manufacturing

## TL;DR

This study investigates the microstructure and thermal properties of tungsten produced by Wire + Arc Additive Manufacturing, demonstrating its suitability for nuclear applications due to favorable microstructure and thermal characteristics.

## Contribution

It provides detailed microstructural and thermal property analysis of additively manufactured tungsten, showing minimal microstructural change after heat treatment and confirming its potential for nuclear sector use.

## Key findings

- Microstructure mainly large elongated grains in as-deposited and heat-treated tungsten
- Heat treatment at 1273 K for 6 hours has negligible effect on microstructure and thermal diffusivity
- Thermal diffusivity and conductivity decrease with temperature between 300 K and 1300 K

## Abstract

Tungsten is considered as one of the most promising materials for nuclear fusion reactor chamber applications. Wire + Arc Additive Manufacturing has already demonstrated the ability to deposit defect-free large-scale tungsten structures, with considerable deposition rates. In this study, the microstructure of the as-deposited and heat-treated material has been characterised; it featured mainly large elongated grains for both conditions. The heat treatment at 1273 K for 6 hours had a negligible effect on microstructure and on thermal diffusivity. Furthermore, the linear coefficient of thermal expansion was in the range of 4.5x10-6 micron m-1 K-1 to 6.8x10-6 micron m-1 K-1; the density of the deposit was as high as 99.4% of the theoretical tungsten density; the thermal diffusivity and the thermal conductivity were measured and calculated, respectively, and seen to decrease considerably in the temperature range between 300 K to 1300 K, for both testing conditions. These results showed that Wire + Arc Additive Manufacturing can be considered as a suitable technology for the production of tungsten components for the nuclear sector.

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Source: https://tomesphere.com/paper/1902.05816