Strain evolution of zirconium hydride embedded in a Zircaloy-2 matrix

In situ synchrotron X-ray diffraction has been used to determine strain evolution in a minority phase, zirconium hydride, embedded in Zircaloy-2 (<100 wt ppm average hydrogen content). The elastic modulus of the hydride is similar to that of Zircaloy-2. Three regimes are observed: I - elastic, II - post-yield load transfer from Zircaloy-2 to hydride, and III - strain saturation, possibly due to hydride fracture. The interpretation is supported by finite element calculations and scanning electron microscopy of the fracture surface.