A molecular dynamics study of bond strength and interface conditions in the Al/Al2O3 metal-ceramic composites

High ductility of metals as well as high strength of ceramics has made the metal/ceramic composites an attractive material for many applications requiring high strength to weight ratios. An important issue in using this material is the behavior of the material and its ceramic-metal interface under various loading, especially at high strain rate. To provide a better understanding of the interface conditions, in this work, a molecular dynamics study of the interface behavior in Al/alpha_Al2O3 composite as the result of tensile and shear loadings is presented. For this purpose, the reactive force field (ReaxFF) potential function is utilized. The effects of crystallographic orientations and atomic layers in the interface region on the deformation and fracture strength of the interface are examined. The radial distribution function, atomic planar density and mean bond length parameters as well as stress-strain curves are employed to identify the strength of the interface structures. The results show the highest tensile and shear strengths in the interface with O-termination of alumina, which can be explained by the formation of strong ionic bonds in the Al/Al2O3 interface. Moreover, the higher atomic planar density in (111) planes of aluminum and its similarity with that of alumina leads to a higher tensile and shear strength in the interface. Furthermore, the deformation mechanism in shear mode is shown to be controlled by planner sliding and local amorphization at the interface zone. (C) 2015 Elsevier B.V. All rights reserved.