Point Defect Clusters in Neutron-Irradiated Molybdenum I. Dose Dependence of the Number Density and the Mean Diameter of Radiation-Induced Dislocation Loops

Molybdenum foils with a nominal purity of 99.95% were recrystallized and degassed at 2300°C and subsequently neutron-irradiated at 80°C with six different doses between 0.5 × 1018 and 24 × 1018 fast neutrons/cm2. The radiation damage was studied by transmission electron microscopy. The number density, n1, and the mean diameter, d, of the small dislocation loops (mainly of interstitial type) were carefully investigated. It is found that n1 and d increase with irradiation time t proportional to tx and ty, respectively, with x ≈︁ 0.27 and y ≈︁ 0.185. A modification of the time exponents due to the finite resolution of the electron microscope is discussed.