Additive manufacturing of tungsten using directed energy deposition for potential nuclear fusion application

Building better nuclear fusion equipment with reduced cost is important for a sustainable society. In this study, pure tungsten is deposited on different steel substrates by directed energy deposition (DED). Specifically, the deposited layers with graded tungsten content by low and high laser scanning speed are fabricated. In addition, the processing parameters were optimized by analyzing the microstructure, phases and defects. Results show that the 9-layer sample (3000 W @ 3000 mm/min) exhibits a better thermal performance, which the thermal conductivity is about 73.75 W/(m.K) at room temperature and 147.45 W/(m.K) at 900 degrees C, respectively. Finally, the surface of the manufactured thick deposited layer by high-low combined laser scanning speed can reach a high tungsten content of up to 99.78 wt%. It is believed that the additive manufacturing of pure tungsten by DED can combine the advantages of tungsten and steel substrates, and simplify the manufacturing process of thermonuclear fusion devices.