Understanding plasticity in zirconium using in-situ measurement of lattice rotations

Abstract: Understanding deformation in polycrystalline metals is critical to use them in high-value high-risk applications. We present in-situ characterisation of plastic deformation of zirconium, a hexagonal closed packed (HCP), metal. Analysis of plastic deformation is performed using electron backscatter diffraction (EBSD) to reveal changes in lattice orientation. Through implementation of TrueEBSD, we can relate the lattice rotations back to the undeformed reference frame. This enables us to explore which slip systems are active and the degree of homogeneous (i.e. deformation with respect to the external load) and heterogeneous (i.e. deformation with respect to the local grain neighbourhood). Additionally, from our analysis, we notice that lattice rotations consistent with a significant fraction <a> pyramidal slip are found. These results are placed in the context of deformation and performance of HCP alloys and zirconium alloys used as nuclear fuel cladding.