The influence of dopants and complexion transitions on grain boundary fracture in alumina

The fracture of micro-cantilever Al₂O₃ specimens containing single grain boundaries is quantified via in situ bending experiments performed in the transmission electron microscope. The type of grain boundary complexion plays a dominant role in determining the fracture response, while the dopant chemistry has a secondary effect for the same complexion type. More ‘ordered’ complexions, those containing sub-monolayer adsorbates, are tougher than the undoped material. The behaviors of SiO₂ and Y₂O₃ doped Al₂O₃ with different complexions are compared and contrasted. In general, grain boundaries exhibiting more ‘disordered’ complexions types, those with multilayer adsorbates, are embrittled relative to undoped Al₂O₃.