Observation of growth of a precipitate at a stress concentration by synchrotron X-ray diffraction

This paper reports X-ray diffraction results obtained during in situ precipitate growth studies. A Zr–2.5Nb specimen containing 60 wt. ppm hydrogen was subject to a thermomechanical cycle in order to precipitate hydrides preferentially at a 15 μm root radius notch. Diffraction patterns were collected as a function of time, during growth of a large (∼100 μm long) notch-tip hydride. The results indicate that hydride precipitation relaxes the crack tip strain field and confirm differences in overload behavior observed at room temperature and 250 °C.