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Scientific Achievement A reactive, dynamic charge interatomic potential for TiC and Ti has been developed within the framework of the third generation charge optimized many-body (COMB3) potential.Significance and ImpactThese findings provide new insights into the generation of misfit dislocations at semi-coherent interfaces and carbide-derived carbons with residual Ti.
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
Liang, T.; Ashton, M.; Choudhary, K.; Zhang, D.; Fonseca, A. F.; Revard, B. C.; Hennig, R. G.; Phillpot, S. R.; Sinnott, S. B., “Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations”. J. Phys. Chem. C (2016), 120, 12530-12538.
Research Details– Structure of coherent and semi-coherent interfaces formed
between close-packed TiC (111) and Ti (0001) is investigated using geometry optimization and classical MD simulations.
– Work of adhesion energies for coherent interfaces is calculated and compared with the DFT predictions.
– For relaxed semicoherent interfaces, a 2D misfit dislocation network is predicted that divides the interface into hexagonal hcp-like regions, fcc-like triangles, and smaller triangular node regions after annealing at 500 K.
– The semi-coherent interface is predicted to be the most stable interface with a larger work of adhesion than the “ideal” Ti-HCP coherent interface.
X
Y
b) Top view
C-FCC C-HCP C-OT
Ti-HCP Ti-FCC Ti-OT
Ti
TiCX
Z
a) Side view
Tiint
Cint
TiTiC
TiTi
Ti2nd
ab
c
a
ba
c
b
b
a
TiC/Ti coherent interfacesTiC : dTi-Ti = 3.05 ÅTi (hcp): dTi-Ti = 2.93 Å
Lattice mismatch:4%
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
Interface dint (Å) Wad (J/m2)DFT COMB DFT COMB
C-FCC 1.1 0.9 12.4 11.58C-HCP 1.3 1.1 10.5 5.70C-OT 1.8 2.0 6.9 1.36
Ti-HCP 2.5 2.5 4.0 1.86Ti-FCC 2.5 2.5 4.0 1.83Ti-OT 2.8 2.8 3.1 1.20
Ti
TiC
Tiint
Cint
TiTiC
TiTi
Ti2nd
Coherent interfaces
Semi-coherent TiC // Ti interfaces
Strain is released by introducing misfit dislocations
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
Ti
Ti-term
TiC
Tiint
TiTi
Ti2nd
Cint
Ti-termination TiC//Ti interface
Semi-coherent TiC // Ti interfaces
Extra Ti atoms relative to TiC, misfit dislocations on
each of the directions within the plane of the
interface
25x25 TiC // 26X26 Ti 0% Lattice mismatch
Tiint, TiTi, Ti2nd
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
Semi-coherent Ti-terminated Interfaces – As-built132.11 Å
76.2
7 Å
hcp-like fcc-likenode
TiC
Ti
TiintTiTiTi2nd
X
Y
25x25 TiC // 26X26 Ti
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
Disregistry at semi-coherent interface
TiintTiTiTi2n
d
44.04 Å
Reference: real-time coherent interface
As-built: infinitesimal misfit dislocations
X
L=66.05 ÅAs-built: infinitesmal disregistry
Y
Relaxed interface Burger’s vector
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
66.05 Å
X
Y]0211[
31
]0011[31
]0101[31
]1102[31
]0101[31 ]1021[
31
fcc-likehcp-likenode
TiintTiTiTi2nd
Misfit dislocation accommodation at relaxed interfaceWork of separation2D misfit dislocation network
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
8
Work of separation2D misfit dislocation network
Charge distribution at interfaces Work of adhesion
Accommodations by misfit dislocations lead the semicoherent interface to be the most stable with
a work of adhesion that is 0.09 J/m2 larger than the “ideal” Ti-HCP
coherent interface
Properties of Ti/TiC Interfaces from Molecular Dynamics Simulations
Misfit dislocation accommodation after annealing at 500 K
