Determination of elastic-plastic properties of hydride precipitate in uranium matrix by nanoindentation and finite element analysis

Abstract

The susceptibility of uranium to hydrogen corrosion results in a decrease in its mechanical and fracture properties which are significant for engineering design and evaluation. In addition to the incorporation of hydrogen in solid solution, hydrogen also leads to uranium hydride precipitation. In this work, uranium hydride is prepared by the reaction of pure hydrogen and uranium at high temperatures, and its morphology and phase structure are characterized. The elastic-plastic properties of hydride precipitate in uranium matrix are studied by nanoindentation and finite element analysis. The stress-strain curve of uranium hydride was obtained for first time by combining depth-sensing indentation with finite element simulations. The accuracy of inversion of stress-strain curves from nanoindentation curves is discussed and compared with the results of similar methods for similar substances (zirconium hydride), showing that the results are reasonable. The anisotropy of Young's modulus of uranium hydride is found to be quite small. The elastic properties of Uranium hydride are discussed and compared with those calculated from density functional theory. The mechanical properties of uranium hydride obtained in this work could provide some critical insights into understanding the growth behavior of hydride and hydrogen embrittlement of uranium.