Local fracture toughness measurements in polycrystalline cubic zirconia using micro-cantilever bending tests

Abstract Local fracture toughness of a polycristalline ceramic was characterized with the micro-cantilever bending method. Beams were milled in single grains of cubic zirconia using a Focused Ion Beam (FIB) microscope. Grains with specific crystallographic orientations were chosen using Electron Backscatter Diffraction (EBSD) measurements to test specific plane families. Notched micro-cantilever beams were loaded up to fracture using a nano-indenter. For fracture toughness evaluation, three different methods were considered: an analytical solution, an isotropic Finite Element Method (FEM) calculation, and an anisotropic FEM model. These three methods gave similar toughness values. A good agreement was found with literature data measured on cubic zirconia single crystals at a macroscopic scale. In this work, no significant difference was noticed for fracture toughness between {100}, {110} and {111} crystallographic plane families. Such method could be used to characterize the local fracture properties of a sample showing extensive cracking such as irradiated nuclear fuel.