Extreme dislocation-mediated plasticity of yttria-stabilized zirconia

Ceramics constitute a major class of engineering materials, but their applications are severely undercut by the propensity to catastrophic brittle fracture. Due to the brittleness and sensitivity to flaws, dislocation-mediated plasticity is rarely achieved in ceramics at room temperature. Here, we report insitu mechanical testing on oriented submicron single-crystal pillars of cubic Atria-stabilized zirconia (YSZ) in the transmission electron microscope, to show that ultra-large plastic deformation mediated by dislocations can be achieved at room temperature. By employing three-dimensional tomography and atomic imaging, unprecedented details of spatial features of the generated dislocations are demonstrated. While deformation in pillars compressed along < 111 > directions is achieved by dislocation slip on the non-close-packed {001} planes, strains in those compressed along < 001 > are by slip on the closepacked [111] planes. Different dislocation slips cause obvious anisotropy in mechanical properties of YSZ crystal. The < 111 > pillars exhibit much greater plastic deformability than the < 001 > pillars, with observed strains as high as 61.6%. These results may lead to potentially new applications of YSZ at submicron scales and provide important insights into deformation mechanisms of ionic ceramics in general. (c) 2021 Elsevier Ltd. All rights reserved.