The interpenetrated composites are of high practical importance. A search for their property improvement is still ongoing. Usually, alumina-interpenetrated composites are filled with an aluminium alloy, AlSi12, which provides the composite with some ductility. However, the skeleton is brittle. In this case, the brittleness resistance of the skeleton is investigated. The interface properties Al2O3/AlSi12 were investigated in [1]. The present study investigates corundum crystals and amorphous alumina with graphene layers. The graphene layers are stacked, displaced, and rotated. The representative volume element (RVE) for corundum consists of a few crystals with graphene layers of different orientations. The equivalent material properties of the RVE are evaluated by focusing on the properties of the phase interfaces within the RVE. In particular, imperfections due to vacancies and impurities are investigated. The analyses are carried out using the LAMMPS environment[2]. Tersoff and Airebo potentials are used to model graphene layers. The COMB3 (Charge-Optimized Many Body) potential is used for alumina and corundum. The results show an increase in the fracture toughness of the Al2O3 material used as the skeleton in the interpenetrated composites, providing hints for the fabrication technology. REFERENCES [1] M. Tahani, E. Postek, T. Sadowski, Diffusion and interdiffusion study at Al- and O-terminated Al2O3/AlSi12 interface using molecular dynamics simulations, Materials, Vol. 16, pp. 4324-1-11, 2023. [2] A.P Thompson, H.M. Aktulga, R. Berger, D.S. Bolintineanu, et. al.. LAMMPS - a flexible simulation tool for particle-based materials modeling at the atomic, meso, and continuum scales. Computer Physics Communications, Vol. 271, pp. 108171-1-33, 2022