Nanoscale ductility in c-plane Al2O3: Dislocation and twinning mechanisms via nanoindentation and molecular dynamics

QQ Xu and I Goda and A Zaborowska and K Mulewska and W Chrominski and D Kalita and L Kurpaska and C Fusco and F Rovaris and WY Huo, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 109, e70420 (2025).

DOI: 10.1111/jace.70420

Brittle oxides, such as alpha-Al2O3, i.e., sapphire, are traditionally unsuitable for ductile applications, yet exhibit enhanced plasticity at nanoscale. This study explores the mechanical behavior of c-plane- oriented, dislocation-free monocrystalline alpha-Al2O3 via molecular dynamics (MD) simulations and experiments, including nanoindentation and post-indentation TEM analysis. The results demonstrate high strength with homogeneous, extensive deformation without failure. Plasticity is dominated by basal (0001) dislocations and rhombohedral 102 twins, which nucleate at deformation onset, as confirmed by MD and TEM. Generalized stacking fault energy (GSFE) and twinning fault energy (TFE) calculations elucidate mechanisms that mitigate crack initiation and propagation on the c-plane, aligning simulations with observations. These insights advance the understanding of nanoscale ductility in oxides, broadening the utility of sapphire in load-bearing micro/nano devices.

Return to Publications page