Irradiation resistance of a thermally stable nanocrystalline Fe-1 at.% Zr alloy

•A thermally stable NC Fe-1 at.% Zr alloy was irradiated in a Helium Ion Microscope.•No He bubbles were observed in the irradiated NC Fe-1 at.% Zr alloy.•The NC Fe-1 at.% Zr alloy exhibits an excellent irradiation resistant property. Nanocrystalline (NC) materials are expected to exhibit excellent irradiation resistant property because of their high volume fraction of grain boundaries. However, the NC materials are usually suspicious to grain coarsening at elevated temperatures. This strongly restricts their applications as practical irradiation resistant materials which are expected to serve at relatively high temperatures. In this work, the irradiation resistant property of a thermally stable NC Fe-1 at.% Zr alloy was examined. The NC alloy was prepared by ball milling method. The irradiation experiments were carried out in a Helium Ion Microscope by 28.4 keV He+ ions to 1 × 1017, 2 × 1017 and 4 × 1017 ions cm−2 at room temperature. The microstructures of the specimens were examined in a Transmission electron microscope. No He bubbles were observed in the irradiated NC Fe-1 at.% Zr alloy, whereas high number density of He bubbles were found to appear in the coarse grained Fe-1 at.% Zr alloy. The results indicate that the NC Fe-1 at.% Zr alloy exhibits an excellent irradiation resistance.