Effect of irradiation on the anisotropic mechanical properties of zirconium through in-situ micropillar compression testing

In-situ ion irradiation and micropillar compression tests were performed on single crystal zirconium to examine orientation dependency for mechanical properties. Specimens were obtained from commercially pure Zr single crystals grown in the [0001] directions. Transmission electron microscopy (TEM) lift-outs were taken from two different orientations of the single crystal with a focused ion beam and shaped into rows of pillars. The pillars were removed to have compression directions of [0001] and within the basal plane [1¯32¯0] and tested using the Argonne National Laboratory Intermediate Voltage Electron Microscope (IVEM) beamline. A lift-out from each orientation was irradiated using 1 MeV Kr²⁺ ions in situ at 30°C to 5 dpa. Microcompression tests showed anisotropic compressive strengths and hardening in both irradiated pillars and non-irradiated pillars as well as a decrease in strength at 300°C. In addition, irradiated pillars in the [1¯32¯0] showed prismatic slip when under compression, which was not observed in the other pillar sets.