Nanoindentation of single- (Fe) and dual-beam (Fe and He) ion-irradiated ODS Fe-14Cr-based alloys: Effect of the initial microstructure on irradiation-induced hardening

• Published in: Journal of nuclear materials 2019-05, Vol.518, p.1-10
• Main Authors: Heintze, C., Hilger, I., Bergner, F., Weissgärber, T., Kieback, B.
• Format: Article
• Language: English
• Subjects: Alloys; Chromium; Dispersion hardening alloys; Dual-beam irradiation; Ferrous alloys; Grain size; Helium; Interfaces; Ion irradiation; Iron; Irradiation; Irradiation hardening; Mechanical alloying; Mechanical properties; Nanoindentation; Nanoparticles; Nanostructured ferritic alloys; Oxide dispersion strengthening; Particle size; Particle-matrix interfaces; Plasma sintering; Radiation; Spark plasma sintering; Yttrium oxide
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2019.02.037

Although the view that nm-sized oxide particles modify and essentially improve the irradiation resistance of Fe-Cr-based alloys is widely accepted, the correctness of this view has only been demonstrated in singular cases. An extension of the field of considered microstructures, irradiation conditions, and measures of irradiation resistance is required. The present study is focused on nanostructured ferritic Fe-14%Cr-based alloys, with and without the addition of 0.6 wt% Y2O3, produced via mechanical alloying and consolidation by spark plasma sintering. The materials were exposed to single-beam (Fe) and dual-beam (Fe and He) ion irradiations at room temperature. The initial microstructures were characterized, bimodal grain size distributions were observed and nanoindentation was applied to measure irradiation hardening for fine-grained and coarse-grained areas separately. We have found that grain size governs irradiation hardening for single-beam irradiation, while oxide nanoparticles play a dominant role for dual-beam irradiations. This sheds a light on the role of particle-matrix interfaces on helium management. [Display omitted] •ODS nano-ferritic alloy exhibits bimodal grain size distribution.•Ion irradiation up to ≈10 dpa at RT gives rise to hardening.•Grain size governs hardening for single-beam (Fe) irradiation.•Grain size and particles play a role for the dual-beam case (Fe + He).•Hardening for the dual-beam case is smaller than for single beam.