Effect of Cr and V coatings on W base material in W-Eurofer brazed joints for fusion applications

Abstract

Titanium diffusion in tungsten is an undesirable phenomenon that may cause the drop of mechanical and thermal fatigue properties of tungsten base material and components in future fusion reactors. To avoid such as problematic, the effectiveness of two different diffusion coatings, deposited onto W base materials by means of RF magnetron sputtering (Cr and V layers), has been studied to analyze its impact on the operative brazing aspects of the W–Eurofer joints. Coatings with two different thicknesses were deposited over tungsten base material prepared using different surface roughness (0.08 and 0.09 μm). The results indicated that Ti diffusion into tungsten base material after the brazing process was suppressed in all cases while the consecution of full metallic continuity was reached. However, both Cr and V layers were dissolved during the brazing process due to the high solubility of both elements into β-Ti. Mechanical properties of the joints dropped especially when Cr is used but a strength higher than 100 MPa was obtained in the case of using V layers.