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.

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