Molecular dynamics-based cohesive zone representation of Ti6Al4V/TiC composite interface

Abstract

In this paper, Molecular Dynamics (MD) simulation is used to simulate the crack propagation along the interface of Ti6Al4V/TiC in Titanium metal matrix composites under Mode-I and II loadings and at different temperatures. MD simulation can then determine the interfacial traction-separation relationship between Ti6Al4V and TiC. The interatomic potential between the atoms in Ti6Al4V/TiC composite is defined by the second-nearest neighborhood modified embedded atom method (2NN MEAM) and the Morse potential. For Vanadium-Carbon (V-C) interatomic potential, the 2NN MEAM parameters are developed and validated based on previous first principle calculations conducted on VC structure. MD simulation results show asymmetrical crack propagation along the interface between Ti6Al4V/TiC and the crack propagates in Ti6Al4V than along the interface. The obtained traction-separation relationship is used to parametrize the cohesive zone model (CZM) for modeling the interface in finite element analysis. Validation of the parameterized relationship is done by finite element simulation of the compression test of Ti6Al4V/TiC at different volume fractions of TiC. A good agreement is shown between the stress-strain results obtained from simulation and the experimental data under the same conditions. Keywords: Ti6Al4V/TiC, Traction-separation, Cohesive zone model, Molecular dynamics simulation