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

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 degrees C to 2 x 10(24) n/m(2) and 3 MeV He-ions at 550 degrees C to 2 x 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 degrees C superplastic behavior occurs for W-0.5TiC-H-2, but is suppressed for W-0.57TiC-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 ultrafine grained W-TiC is capable of improved performance as the spallation neutron source solid target. (c) 2008 Elsevier B.V. All rights reserved.