Amorphous and anisotropic surface relief formation in tungsten under repeated high-flux hydrogen plasma loads

Yu Li (Corresponding author), Junhua Hou, Varun Shah, Yuhe Huang, J.A.W. (Hans) van Dommelen, Wenjun Lu, Qiang Zhu, Thomas W. Morgan

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Facing extreme plasma loads, the structural integrity of the tungsten divertor is crucial for ITER, an engineering marvel in nuclear fusion reactors, to achieve its fusion performance targets. Induced by repeated transient heating from plasmas, the thermal fatigue damage of tungsten–typically accompanied by the formation of surface relief–has been identified as a critical issue but an in-depth understanding is still lacking. Here, we report the formation of amorphous and anisotropic surface relief on ITER-grade tungsten surfaces under ITER-relevant hydrogen plasma loads. Measured by both electron backscatter diffraction over large fields of view and transmission Kikuchi diffraction of site-specific lamellae, such surface relief preferentially forms on grains with {1 1 0} planes parallel to the surface. This cannot be explained by the orientation-dependent resolved shear stress according to the Schmid law, threshold displacement energy anisotropy, or oxidation anisotropy. Furthermore, surface relief amorphization is revealed by high-resolution transmission electron microscopy imaging and selected area electron diffraction analysis, and is explained by a novel vacancy-induced amorphization mechanism. The results provide new insights into the thermal fatigue behavior of tungsten for fusion applications.
Originele taal-2Engels
Aantal pagina's12
TijdschriftNuclear Materials and Energy
StatusGepubliceerd - dec. 2023


We acknowledge the support of the Magnum-PSI Facility Team at DIFFER. The Magnum-PSI facility at DIFFER has been funded by the Netherlands Organisation for Scientific Research (NWO) and EURATOM. This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200— EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them. Yu Li acknowledges financial support from the China Postdoctoral Science Foundation ( 2022M711468 ) and GuangDong Basic and Applied Basic Research Foundation (2022A1515110023). This work was financially supported by Shenzhen Science and Technology Innovation Commission under the Projects (No. JCYJ20210324104610029, No. KQTD20170328154443162 and No. JCYJ20220818100613028).

H2020 Euratom
European Commission101052200— EUROfusion
China Postdoctoral Science Foundation2022M711468
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Science, Technology and Innovation Commission of Shenzhen MunicipalityKQTD20170328154443162, JCYJ20210324104610029, JCYJ20220818100613028
Basic and Applied Basic Research Foundation of Guangdong Province2022A1515110023


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