The defects which were formed in Ni-based alloys, neutron-irradiated at 473 or 573K, were examined by means of electron microscopy. In specimens which were irradiated at 473K, a high density of interstitial loops and small vacancy clusters with stacking-fault tetrahedra were observed. The number densities of these 2 types of defect did not depend strongly upon the amount of solute in the alloy. The density of the loops in Ni-Si alloys was much higher than that in Ni-Cu or Ni-Fe alloys, while the density of stacking-fault tetrahedra depended only slightly upon the type of solute. Also, the size of the loops depended upon the type and amount of solute. In Ni-Cu specimens which were irradiated at 573K, a high density of dislocation lines developed during the growth of interstitial loops. In Ni-Si alloys, the number density and size of the interstitial loops changed as a function of the amount of solute. Voids were formed in the Ni-Cu alloys, but scarcely formed in Ni-Si alloys. The number density of voids was 1% of that of the stacking-fault tetrahedra which were observed in 473K-irradiated Ni-Cu alloys.

Damage Structures in Fission-Neutron Irradiated Ni-Based Alloys at High Temperatures. K.Yamakawa, Y.Shimomura: Journal of Nuclear Materials, 1999, 264[3], 319-26