Microstructural analysis of tungsten single crystals irradiated by MeV W ions: The effect of irradiation dose and temperature

Abstract

We investigated the microstructural evolution of W(111) single crystals under high-energy self-ion irradiation at 290 K and 800 K, using complementary characterization techniques, including Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Rutherford backscattering spectrometry in channelling regime (RBS-C), Positron annihilation spectroscopy (PAS), and Nuclear reaction analysis (NRA). Irradiation with MeV W ions allowed for controlled defect formation, with dose and temperature significantly affecting defect type and distribution. At 290 K, interstitial defects evolved from dislocation loops at low doses (0.02 dpa) to dislocation networks at higher doses (0.2 dpa). In contrast, at 800 K, lower dislocation densities were observed, with nm-sized dots and isolated lines forming at 0.02 dpa and developing into longer dislocation lines (∼30 nm) at 0.2 dpa. RBS-C spectra support these findings, showing a trend of increasing dislocation density with dose but decreasing with temperature. PAS analyses revealed mono-vacancies and small vacancy clusters (V 2 –V 4 ) at 290 K, coalescing into larger clusters (V 25 –V 50 ) at 800 K. NRA measurements indicated greater deuterium retention at 290 K than at 800 K, consistent with lower vacancy mobility at the lower temperature. Combined TEM, RBS-C, PAS, and NRA observations highlight increased vacancy mobility and defect recombination with temperature, forming larger vacancy clusters at 800 K. This comprehensive study provides quantitative insights into defect formation and evolution in W single crystals, presenting a comparative analysis of defect distributions across multiple techniques and revealing temperature-dependent mechanisms of microstructural change. • SEM, TEM, RBS-C, PAS, and NRA analytical techniques were used to investigate self-damaged W(111), and critically evaluate and compare the results. • Heavy ion irradiation at 290 K forms dense dislocation networks, while at 800 K, sparse dislocation lines and larger vacancy clusters dominate. • Samples irradiated at 290 K have higher deuterium retention than those at 800 K, due to recombination of defects at higher temperatures. • PAS revealed vacancy cluster sizes scaling with dose and temperature, transitioning from V 2 –V 4 at 290 K to V 25 –V 50 at 800 K. • Irradiation-induced defects coincide with SRIM-predicted damage profiles, with damage extending deeper at elevated irradiation temperatures.

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