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Mechanical properties of tough nanocomposites: a computational study by molecular dynamics

Wednesday (26.09.2018)
15:15 - 15:30 S1/03 - 23
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Nanocomposites formed by hard nanocrystallites embedded in a self-lubricant matrix show a unique combination of properties (low friction, high hardness, high toughness, low wear) which make them an excellent choice for protective applications. In this work, the system TiC/a-C is studied as a characteristic combination among these nanocomposites. This study aims at contributing to the understanding of the mechanical properties, in particular the high resistance to fracture propagation. A computational approach has been preferred to avoid the issues observed in the experimental approach, which is limited by the lack of standard measurements of that property, and the indetermination and/or interdependence of several characteristics of the material (for instance, chemical composition and grain size).


Thus, molecular dynamics simulations were carried out using LAMMPS package, using periodic boundary conditions. A 2NN-MEAM (second nearest-neighbor modified embedded atom) potential was selected, since it reproduces reasonably most of the properties of the phases that can be formed with Ti and C (TiC, a-C, graphite, diamond). The model shows semi-quantitative results in the elastic part of the deformation (through stress-strain curves). In the plastic part, although the results are mostly qualitative, it is possible to obtain a mechanism that explains the toughness of these nanocomposites, both in 2D and in 3D, which can be used to improve its design and optimize its applicability.

 

Speaker:
Dr. Diego Martinez-Martinez
University of Minho
Additional Authors:
  • Prof. Dr. Olalla Faza
    University of Vigo