The Tensile Deformation of Multiphase Al2O3: Insights from Molecular Dynamics Simulations

Abstract

Multiphase Al2O3 samples are simulated using molecular dynamics method. These samples consist of γ-Al2O3 and α-Al2O3 crystals embedded in a disordered phase matrix. The stress–strain curves of these samples show elastic and plastic deformation. Structural analysis indicates that the AlO bond lengths are stretched and the geometries of the AlOx (x = 4, 5, and 6) units are distorted during tensile deformation. AlO bond breakage causes the transformation of AlOx units; AlO4 increases while AlO6 decreases with increasing strain. The γ-Al2O3 and α-Al2O3 crystals transfer into the disordered phase, while a small number of atoms recrystallize under tensile loads. In plastic deformation, large simplexes with radii above 1.958 Å increase rapidly with increasing strains above 0.116, with the large simplexes coalescing to form the clusters in the disordered phase. The number of large simplexes in the largest cluster increases with increasing strain values above 0.127. The growth and coalescence of large simplexes in the disordered phase cause microscopic crack formation at high strains.