Neutron damage in molybdenum irradiated at high temperatures

Transmission electron microscopy has been used to characterize the microstructure of polycrystalline molybdenum irradiated at elevated temperatures (> 0·3T m). Irradiation at 700°c produces dislocation loops within the grains and denuded zones along grain boundaries, while irradiation at 1000°c results in generally loop-free grains which occasionally contain bands of loops and dislocation debris parallel to grain boundaries. Diffraction contrast analyses show that most of the loops are interstitial edge type, having a/2〈111〉 Burgers vectors, but that a few a〈100〉 loops are also present. Irradiation at these temperatures also produces small voids which are interpreted as representing aggregates of radiation-induced vacancies.