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Micro-scale structuring of WRe by femtosecond laser ablation
Tungsten and its alloys show many beneficial properties for a wide range of highly demanding applications. Examples are first wall materials for proposed fusion reactors and conversion layers of stationary and rotating X-ray anodes, where a high melting point, high thermal conductivity, and low thermal expansion are crucial [1–3]. The already impressive inherent properties of the material can further be improved by introducing artificial topographical structures on the surface. A potential method for the fast structuring of large areas with micro-scale features is provided in the form of femtosecond laser ablation [4–6]. Especially the introduction of deep, narrow cuts with high aspect ratios offers the possibility of relieving cyclic thermal stresses in the aforementioned use cases, which is of special interest. Furthermore, the localized and minimal heat deposition by the laser and therefore neglectable impact on the microstructure is beneficial [7,8].
This work investigates the potentials and limitations of introducing micro-scale cuts with a depth of several hundred micrometers in a commercially available WRe alloy using a femtosecond laser ablation system. The depth, aspect ratio, eventual impact on the surrounding microstructure, and retained deformation are investigated through confocal laser scanning microscopy, scanning electron microscopy, electron backscatter diffraction, and micro-computed tomography scans. A parameter study on different laser parameters like power, pulse distance, line count, and repetition number is conducted to determine the optimum for fast structuring with beneficial cut characteristics.
References
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