Crystal orientation dependence of ion-irradiation hardening in pure tungsten

Pure tungsten (W) single crystals of {0 0 1} and {0 1 1} surface orientations were irradiated with 6.4 MeV Fe3+ ions up to 1 dpa at 573 K. The TEM examination revealed that there was a very small orientation dependence in the radiation damaged microstructure, showing that both W{0 0 1} and W{0 1 1} exhibited a double black band structure with high number density of dislocation loop rafts in the black bands. However, the depth profile of ion-irradiation hardening evaluated by nanoindentation (NI) technique turned out to show a clear orientation dependence, namely, W{0 0 1} showed a deeper NI hardness profile than W{0 1 1}.