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Molecular Dynamics Study of Crack Propagation at the Interface between Al and α-Al2O3

Author: LaiXin
Tutor: LiuLiSheng
School: Wuhan University of Technology
Course: Solid Mechanics
Keywords: Molecular Dynamics Crack Al/α-Al2O3 interface Dislocation Interface interaction potential
CLC: O346.1
Type: Master's thesis
Year: 2010
Downloads: 235
Quote: 0
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Abstract


Ceramic / metal interface exists in the ceramic / metal composite materials, as well as a variety of insulation coating, military armor, catalytic converter, field effect transistors, anti-corrosion coatings and other chemical and electronics industries, it's physics, chemistry and materials science performance has been a structural composites, porcelain fixtures and eco paints hot area of ??research problems, research ceramic / metal interface structure and strength, as well as in micro-defects and micro-cracks under the conditions of the mechanical behavior and failure process, not only for the ceramic / metal composite material damage in the form of applications and control is extremely important, and other composite materials research has far-reaching significance. In this paper, using the method of molecular dynamics study 300K temperature Al/α-Al2O3 interface crack in the thickness direction under the action of tensile strain on the expansion process, observed the formation of dislocations and development of crack growth and proliferation for the study Al/α--Al2O3 Composites mechanical properties and service behavior to provide a reference. In this paper, a parallel molecular dynamics method and the use of open source LAMMPS research Al/α-Al2O3 interface crack propagation law. Specific studies are as follows: 1, through literature, from the experimental observations and the results of first-principles calculations to get Al/α-Al2O3 main interface atomic arrangement of the crystal orientation and the law, constructed Al/α-Al2O3 interface atomic model. 2, the elastic constants, surface energy and interfacial energy is the characterization of materials and material properties of a few basic physical interface. In order to simulate the molecular dynamics method can interface the physical and mechanical behavior of the potential function should be able to correctly reflect the material on which the several physical quantities. According to this principle, this paper used the current analog Al and Al2O3 atomic interaction potential was evaluated, selected to accurately reflect the role of the physical potential; Then, in considering the way of bonding between atoms on the basis of interfacial atoms combined with the current Experimental and theoretical research to determine the interfacial interaction potential in the form, and then to the experimental values ??of the interfacial energy and first-principles calculation of value as a reference value, the potential effect on the interfacial atomic potential function parameters were fitted to determine the interface atomic interaction potential. Finally, respectively, from the structural stability and interfacial atomic configuration of the relevant potential function has been verified. 3, the use of molecular dynamics simulations of 300K temperature Al/α-Al2O3 interface crack under axial tensile strain crack growth process. Observed that, when the strain loading to 5.52%, the dislocation emitted started by the interface crack and strain of 6.36% in the form dislocation loops, its three principal surface and interfacial dislocations flat angle of about 71 °. With increasing strain, dislocation along the Al-oriented slip dislocation and accumulate in α-Al2O3/Al interface, Al in a continuous increase in the dislocation density, Al continue to be strengthened. When the resistance is greater than the dislocation crack resistance, the material can not be absorbed by generating dislocation strain energy, then the cracks began to expand. As the strain continues to increase, Al ductile failure will ultimately cause the entire material system failures.

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CLC: > Mathematical sciences and chemical > Mechanics > Solid Mechanics > Strength theory > Fracture theory
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