Nanoscale flaw tolerance behaviour of polycrystalline tetragonal zirconia nanopillars

N Zhang and MA Zaeem, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 173, 105405 (2020).

DOI: 10.1016/j.ijmecsci.2019.105405

Flaw tolerance behaviour of polycrystalline tetragonal zirconia nanopillars under compression is investigated by completing a series of large-scale atomistic simulations. Our simulation results show that the observed tetragonal to monoclinic phase transformation in zirconia does not necessarily nucleate around a pre-existing defect. A competing mechanism between grain boundary (GB)-induced and void-induced phase transformation is revealed. This work is the first direct atomistic simulation of flaw tolerance behavior in shape memory ceramics that offers a pseudo Griffith relationship between the strength, void size, and average grain size. The key finding is that the mechanical properties, particularly the strength, can become insensitive to a pre- existing defect in certain conditions depending on the average grain size and defect size. The obtained results provide new insight into the deformation mechanisms of defective polycrystalline tetragonal zirconia nanopillars.

Return to Publications page