Ion-irradiation induced clustering in W-Re-Ta, W-Re and W-Ta alloys: an atom probe tomography and nanoindentation study

Journal article

In tungsten plasma-facing fusion reactor components, Ta is the third most abundant element formed by transmutation (after Re and Os), yet little is known about the behaviour of W-Ta alloys under irradiation and any effects Ta might have on Re clustering in W-Re-Ta alloys. In this study, W−4.5at.%Ta, W−2at.%Re−1at.%Ta and W−2at.%Re alloys were exposed to 2 MeV W+ ions to a fluence of 2.64x1015 ions.cm-2 at temperatures of 573 and 773 K. Atom probe tomography and nanoindentation were used to characterise the chemical and physical properties of the irradiation-induced clusters and the mechanical properties of the irradiated layer. In the W-Ta alloy, no evidence of irradiation-induced clustering was found. In the W−Re−Ta alloy, at both irradiation temperatures studied the presence of Ta reduced the W-Re cluster number density and volume fraction compared to that in the W-Re alloy; however it did not alter cluster composition as the Ta was rejected from the clusters. The reduced cluster density in the W-Re-Ta alloys was associated with a smaller degree of irradiation hardening than in the W-Re alloys. Possible mechanisms by which Ta hinders cluster development are discussed.

Authors: Xu, A; Armstrong, D; Smith, G; Moody, M; Beck, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Acta Materialia
• Volume: 124
• Pages: 71–78
• Publication date: 2016-01-01
• Acceptance date: 2016-10-20
• DOI: 10.1016/j.actamat.2016.10.050
• ISSN: 1359-6454
• Keywords: tungsten rhenium tantalum alloys; atom probe tomography; ion-irradiation; nanoindentation; nuclear fusion