DEFECTS IN METALS AND SIMULATION OF MECHANICAL ...

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dislocations at a penetration depth of 9 Ǻ, while Fig. 2-5 (b) shows the atomic arrangement at a depth just after 13 Ǻ, where dislocations have clearly formed. Snapshots at two different depths of the indenter for 0.05% vacancy concentration are shown in Fig. 2-6 Fig.2-6: Indentation into solid with 0.05% Vacancies a) View at a depth of 9Ǻ showing atoms with decreased number of nearest neighbors b) View at the yield load with depth13 Ǻ. 12
In Fig. 2-6 a) and b) we can see that the vacancies are moving toward the indentation surface and at the yield load vacancies combine with nucleating dislocations which explains the decrease in the yield load when having dislocations inside the simulation cell. 800 700 y = 497.11 * x^(-0.082726) Load, nN 600 500 400 300 200 100 m/s 20 m/s 0.01 0.1 1 Vacancy concentration, % Fig.2-7: Yield loads for different vacancies concentrations and for two different indentation velocities 100m/s and 20m/s The results of MD simulations run at various vacancy concentrations and penetration rates, and tracking the load at which the first evidence of plastic deformation occurs are shown in Fig. 2-7. In general, the load at yielding decreases with increasing vacancy concentration at concentrations above 0.01%. The relation between the yield load versus the vacancy 13
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: Fig.2-5: Indentation with 0% Vacanc
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 and 32: Atomistic computer simulation techn
Page 33 and 34: Figure 3-1 shows the simulation box
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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