Strengthening Behavior and Tension–Compression Strength–Asymmetry in Nanocrystalline Metal–Ceramic Composites

Abstract

Metal–ceramic composites are an emerging class of materials for use in the next-generation high technology applications due to their ability to sustain plastic deformation and resist failure in extreme mechanical environments. Large scale molecular dynamics simulations are used to investigate the performance of nanocrystalline metal–matrix composites (MMCs) formed by the reinforcement of the nanocrystalline Al matrix with a random distribution of nanoscale ceramic particles. The interatomic interactions are defined by the newly developed angular-dependent embedded atom method (A-EAM) by combining the embedded atom method (EAM) potential for Al with the Stillinger–Weber (SW) potential for Si in one functional form. The molecular dynamics (MD) simulations are aimed to investigate the strengthening behavior and the tension–compression strength asymmetry of these composites as a function of volume fraction of the reinforcing Si phase. MD simulations suggest that the strength of the nanocomposite increases linearly with an increase in the volume fraction of Si in the Al-rich region, whereas the increase is very sharp in the Si-rich region. The higher strength of the nanocomposite is attributed to the reduced sliding/rotation between the Al/Si and the Si/Si grains as compared to the pure nanocrystalline metal.