Annealing of hardening in copper after neutron irradiation hardening at 77 K

The stress–strain curves corresponding to single crystals of Cu irradiated and measured at 77 K revealed the onset of an upper and a lower yield point at fluences higher than 0.5×1021 n m−2 (E>0.5 MeV), which will be referred to as the critical fluence, (φt)C. The lower yield point is associated to the channeling dislocation phenomenon. The upper yield point is taken as the actual yield stress. The isochronal recovery of the critical resolved shear stress (CRSS) around Stage V (T>450 K) in crystals irradiated at 300 K at fluences higher than (φt)C, and at 77 K at fluences close to (φt)C, was studied in the present work. For both conditions, the presence of a broad recovery stage between 500 and 650 K (Stage V) was determined. In the second case, the presence of three inflections in the isochronal recovery of the CRSS (measured at 77 K), in the temperature sub-ranges: ∼490–520; ∼520–560 and ∼560–620 K was observed.