An investigation of structural changes caused by neutron irradiation of a uranium molybdenum alloy

Abstract

Specimens of an alloy containing 9 wt per cent of molybdenum were irradiated. The electrical resistance was measured and the structure examined by X-ray diffraction and metallographic techniques. The specimens were prepared by suitable heat treatment to have eutectoid α + γ′ structures with various degrees of dispersion. It was established that the rate of homogenization of these two-phase structures during irradiation was inversely proportional to the square of the thickness of the laminae in the eutectoid. In the homogeneous γ-phase changes in structure and properties under irradiation are essentially complete in 2–4 hr. The ordered γ′-phase was found to be disordered after a few hours of exposure to neutrons.

All these phenomena can be adequately explained on the basis of the theory already published.⁽²⁾ However the size of the thermal spike and the energy dissipated were found to be smaller than determined previously and were 2·5 × 10⁻¹⁷ cm³ and 2 MeV respectively.