DEFECTS IN METALS AND SIMULATION OF MECHANICAL ...

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The simulation box has a rectangular shape with dimension of [96.6 96.6 161] Angstroms. Periodic boundary conditions at constant volume were applied along all three principal axes. The simulations were carried at two different temperatures, 300K and 400K, and the number of atoms in the simulation box was selected in accordance with the primary knock-on atom energy, temperatures during the hit were almost stable with no major fluctuations. Our systems are set to satisfy the statistics of the microcanonical ensemble NVE, in the NVE ensemble the system is isolated from changes in moles (N), volume (V) and energy (E), the NVE ensemble was recommended for Cascade Modeling by J. P. Crocombette [ 33 ]. The Primary Knocked on atom energy was varied between 1 Kev to 3 Kev for both temperatures, other investigators used a range of PKA energies that varied from 0.5 Kev to 100 Kev and sometimes more, for instance G. R. Odette et al.[ 36 ] showed the average number surviving defects as a function of PKA energy, their numbers make a correlation with the numbers found for cascade modeling found for Zirconium. Fig.3-1: Simulation Box for Zirconium HCP 22
Figure 3-1 shows the simulation box created using the HCP structure for Zirconium, potentials for Zirconium [ 37 ] from the LAMMPS library of potentials were used. Lattice parameter (A) Simulation box dimensions (A) Timestep (picoseconds) 3.22 [x=96.6 y=96.6 z=161] 0.001 Table.3-2: Simulation of radiation damage in Zirconium constants. Results and Discussion At the start of the simulation a file is set to assemble the output of the simulation. This allows the number of vacancies to be measured as a function of time, and have snapshots of the simulation box. This means the formation and annealing of defects can be measured. Fig. 3-2: Defects formation at the beginning of the simulation. Atoms with a non-perfect co-ordination number are shown as colored atoms, all other atoms removed. 23
Page 1 and 2: DEFECTS IN METALS AND SIMULATION OF
Page 3 and 4: ACKNOWLEDGMENTS The time and commit
Page 5 and 6: dislocations on yield load were als
Page 7 and 8: LIST OF TABLES Page Table.2-1: Forc
Page 9 and 10: Fig. 3-2: Defects formation at the
Page 11 and 12: Chapter 1 Motivation The motivation
Page 13 and 14: experiments, the advantage is that
Page 15 and 16: Chapter 2 Vacancies effect on metal
Page 17 and 18: showing no dislocation nucleation b
Page 19 and 20: Fig. 2-3: Force displacement curves
Page 21 and 22: Fig.2-5: Indentation with 0% Vacanc
Page 23 and 24: In Fig. 2-6 a) and b) we can see th
Page 25 and 26: Vacancy concentrations were varied
Page 27 and 28: The load at yielding is also sensit
Page 29 and 30: Fig. 2-9 shows that with a higher s
Page 31: Atomistic computer simulation techn
Page 35 and 36: Fig. 3-4a: Defects after the initia
Page 37 and 38: In Fig. 3-5 we can see the evolutio
Page 39 and 40: Fig. 3-6: Fraction Nv/n of survivin
Page 41 and 42: Chapter 4 Dislocations effect on Me
Page 43 and 44: The dislocation was created by remo
Page 45 and 46: Fig. 4-3: Edge dislocation in the (
Page 47 and 48: For iron the shear modulus, µ, is
Page 49 and 50: Fig.4-6: Simulatin showing dislocat
Page 51 and 52: Chapter 5 Conclusion Defects in met
Page 53 and 54: [ 14 ] D.F. Bahr, D.E. Kramer, and
Page 55: [ 47 ] H. G. M. Kreuzer and R. Pipp

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