Dresden 2026 – scientific programme
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FM: Fachverband Funktionsmaterialien
FM 11: Poster Session Functional Materials
FM 11.17: Poster
Tuesday, March 10, 2026, 18:00–20:30, P4
Impurity-Driven Vacancy Evolution in Irradiated Tungsten Revealed by Positron Annihilation Spectroscopy and Multiscale Modeling — •Zhiwei Hu1,2, Qigui Yang3, Jintong Wu4, François Jomard5, Thomas Jourdan6, and Marie-France Barthe2 — 1HZDR, Dresden, Germany — 2CEMHTI-CNRS, Orléans, France — 3KTH, Stockholm, Sweden — 4University of Helsinki, Finland — 5GEMAC; Versailles; France — 6CEA,Gif-sur-Yvette, France
Thermonuclear fusion demands plasma-facing materials that withstand extreme heat and irradiation. Tungsten, selected for ITER, develops microstructural evolution. Predicting defects behavior is therefore crucial. Using Positron Annihilation Spectroscopy, TEM, atomistic modeling, and DFT, irradiation-induced defects were examined. A new PAS data-inversion method using quadratic programming and two-component DFT was created. This method reconstructs full vacancy-cluster distributions from PAS data. Results show small vacancy clusters dominate after high-temperature irradiation. These clusters remain invisible to TEM yet strongly affect microstructure. Room-temperature electron irradiation showed reduced pure vacancy fractions. Unexpected positron traps were observed. SIMS and DFT identified these traps as oxygen-vacancy complexes. Cluster-dynamics simulations confirmed oxygen interacts with Frenkel pairs. Such interactions significantly modify defect evolution. Comparative irradiations of varying-purity tungsten were performed, PAS and TEM together revealed impurity effects.
Keywords: Tungsten; Microstructure; Defect; Impurity; Fusion