Development of ultra-fine grained W–(0.25–0.8)wt%TiC and its superior resistance to neutron and 3 MeV He-ion irradiations

Abstract W–(0.25–0.8)wt%TiC with equiaxed grain sizes of 50–200 nm and nearly full density of 99% was fabricated utilizing mechanical alloying (MA) in different gas atmospheres of H 2 , Ar and N 2 and hot isostatic pressing. Microstructural and mechanical property examinations were conducted before and after irradiations with neutrons at 600 °C to 2 × 10 24  n/m 2 and 3 MeV He-ions at 550 °C to 2 × 10 23 He/m 2 . It is found that TiC additions and MA atmospheres significantly affect grain refinement and baseline mechanical properties. The room-temperature fracture strength takes a maximum of 2 GPa for W–(0.25–0.5)%TiC with MA in H 2 (W–(0.25–0.5)TiC–H 2 ). At 1400–1700 °C superplastic behavior occurs for W–0.5TiC–H 2 , but is suppressed for W–0.5TiC–Ar. No neutron irradiation hardening is recognized in W–0.5TiC–H 2 and W–0.5TiC–Ar. The critical fluence for surface exfoliation by He irradiation for W–0.3TiC–H 2 is more than 10 times as large as that for commercially available W materials. These results suggest that ultra-fine grained W–TiC is capable of improved performance as the spallation neutron source solid target.

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