2005 Fiscal Year Final Research Report Summary
Resistance to the motion of singular points in a crystal due to emission of lattice waves
| Project/Area Number |
16560582
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical properties of metals
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| Research Institution | Meiji University |
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Principal Investigator |
KOIZUMI Hirokazu Meiji University, School of Science and Technology, Professor, 理工学部, 教授 (60126050)
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| Project Period (FY) |
2004 – 2005
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| Keywords | dislocation / kink / crack / phonon / radiation loss / velocity / simulation / elastic body |
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| Research Abstract |
In the frame of the elasticity theory dislocations, kinks on a dislocation line and cracks are treated as singular lines or points in a continuous body. One of the most serious problems in this treatment is that discreteness of the lattice cannot be taken into account. When these singular points move, they accelerate and decelerate according to periodicity of the lattice, which leads to dissipation of kinetic energy of the singular points. Studies on radiation loss have been made.
1.Motion of kinks on a screw dislocation was simulated in a diamond lattice. Atoms interact with Stillinger-Weber potential. Although the velocity of the kink is an increasing function of the applied stress, a jump is observed in the velocity-applied force relation when the spectrum of the emitted phonon changes abruptly. For a large applied stress, multi-kink formation occurs as has been predicted by the line tension model of a dislocation.
2.Motion of a crack of mode III is simulated in a simple cubic lattice. Lattice waves are emitted when a bond is broken. Magnitude of the surface energy affects the fastest velocity of the crack. Supersonic motion is observed only for the system with a small surface energy.
3.If a dislocation is placed on the top of the Peierls potential, it moves down to the bottom of the Peierls valley under no applied stress emitting lattice waves and oscillates at the bottom of the Peierls valley. The oscillation of the dislocation can be approximated by a damping oscillator.
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