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Large-scale Classical Molecular Dynamics Simulations of Novel Nano-ceramic Matrix Composites |
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One of the key focus areas in the nanomaterials technology is the development of nanocrystalline materials with desired improvements in the mechanical, thermal, and electrical properties. Examples of such nanomaterials are nanocrystalline Al, Cu, and Al-Cu alloys produced using nanoparticle consolidation procedures; nanocrystalline Ni, Al, Cu, Ti, and Fe-Cu alloys produced using severe plastic deformation procedures; and nanocrystalline Ni produced using electrodeposition procedures. Presence of more than a component in some nanocrystalline materials further adds to improvements in the desired properties. It has been shown recently that addition of a random dispersion of single walled carbon nanotubes (SWCNTs) to nanocrystalline Al2O3 results in significant improvement in the fracture toughness and strength. Further addition of a ductile Fe or Nb nanocrystalline phase results in toughening of the ceramics by almost 300%, see reference [2]. The average grain size in these composites varies from 20 nm for metallic Nb or Fe phases to 100 nm for the ceramic Al2O3 phase. Recently, it has also been observed that these nanoceramic matrix composites have excellent thermal barrier coating properties. These and other experimental developments have motivated the proposition of new computational nanomechanical frameworks that are able to predict the effect of nanocomposite materials phase morphology on the desired set of properties. Using this framework we have analyzed dynamic strength as well as defect nucleation and propagation in nanocrystalline Al+Fe2O3 composites as a function of the loading directionality (tension/compression), volume fraction of the individual phases, and phase morphology of the composites. In this proposal, a modification to this framework is proposed to be used for analyzing dynamic fracture resistance of Al2O3 based nanoceramic matrix composites (Al2O3+Fe+SWCNT and Al2O3+Nb+SWCNT).
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