Radiation damage evolution in pure W and W-Cr-Hf alloy caused by 5 MeV Au ions in a broad range of dpa. (December 2021)

• Record Type: Journal Article
• Authors: Macková, A.; Fernandes, S.; Matejíček, J.; Vilémová, M.; Holý, V.; Liedke, M.O.; Martan, J.; Vronka, M.; Potoček, M.; Bábor, P.; Butterling, M.; Attallah, A.G.; Hirschmann, E.; Wagner, A.; Havránek, V.
• Is Part Of: Nuclear materials and energy. Volume 29(2021)
• Publication Date: 2021-12
• Subjects: W and W-Cr alloy ion irradiation -- Radiation damage -- Fusion materials -- Structure analysis of defects; Nuclear energy -- Periodicals; Nuclear fuels -- Periodicals; Nuclear reactors -- Materials -- Periodicals; Radioactive substances -- Periodicals; 621.4833
• DOI: 10.1016/j.nme.2021.101085
• Languages: English
• ISSNs: 2352-1791

Abstract

Highlights: Au-5 MeV ion irradiation in W and W-Cr-Hf alloys was used in a broad range of dpa. W-Cr-Hf exhibited high defect dynamics and defect cluster size decrease at higher fluences. Damage bands appeared in W-Cr-Hf with long separated dislocations beyond the irradiated layer. W exhibited localized defect clusters growing in size with the increasing irradiation fluence. Thermal properties are modified in accordance with defect dynamics. Abstract: Pure W and W-Cr-Hf alloy which are prospective materials for nuclear fusion reactors, such as DEMO, were irradiated at room temperature with 5 MeV Au 2+ ions with fluences between 4 × 10 14 and 1.3 × 10 16 ions.cm −2 to generate various levels of lattice damage from about units up to tens of dpa. The distinct character of radiation damage accumulation, microstructure and defect nature have been observed in both pure W and W-Cr-Hf alloys, the latter exhibited interesting ability of damage reorganisation and defect size decrease at the higher ion fluences as determined by positron annihilation spectroscopy (PAS). High radiation damage rate in the irradiated layer has been evidenced in the W samples already at the lower Au-ion fluences compared to W-Cr-Hf samples, where the damage increased in steps with the increasing Au-ion fluence. The distinct defect accumulation was accompanied with the different Au-ion implanted distribution in the irradiated layer determined by Secondary Ion Mass Spectrometry (SIMS) as well as the thermal properties have shown the consequent worsening in the depth in good agreement with the Au-depth concentration profiles. TEM corroborated above mentioned findings, where the sub-surface layer exhibited defect release after the irradiation, the maximum of dislocation loop density has been identified in the depth according the predicted dpa (displacement particles per atom) maximum for the lower Au-ion fluences. Moreover, TEM shows the dislocation density band structure appeared in W-Cr-Hf samples exhibiting the high density defect band according the projected range of the Au-ions simultaneously with the additional layer with larger isolated dislocations pronounced in the higher depth as a growing function of Au-ion fluence. Such phenomenon was not observed in W samples.