Evaluating zirconium–zirconium hydride interfacial strains by nano-beam electron diffraction

Nano-beam electron diffraction has been used to quantify the elastic strain field associated with δ-hydride needles embedded in an α-Zr matrix. It has been found that the volume misfit associated with precipitation results in elastic strains that are ∼4× greater in the matrix than the hydride. Electron energy loss spectroscopy was used to detect hydrogen enrichment at the matrix–hydride interface by a shift in the zirconium plasmon peak. This work highlights that γ-hydride is metastable and acts as a precursor to equilibrium δ-hydride and that compositional variations within the hydride can be detected using electron energy loss spectroscopy.