Chapter 4 Imperfections Point and Line Defects Dimensional
- Slides: 62
Chapter 4 Imperfections: Point and Line Defects
Dimensional Range for Different Classes of Defects
Stress Required to Shear a Crystal
Theoretical Shear Strength of Some Materials
Point Defects Atomic point defects. Two most common point defects in compounds: Schottky and Frenkel defects.
Point Defects Interstices in FCC structure. (a) Octahedral void. (b) Tetrahedral void. Interstices in the BCC structure. (a) Octahedral void. (b) Tetrahedral void. Interstices in the HCP structure. (a) Octahedral void. (b) Tetrahedral void.
Formation of Point Defects Formation of point defects by the annihilation of dislocations. (a) Row of vacancies. (b) Row of interstitials.
Shear stress-Shear Strain Curves for Aluminum Single Crystal Shear stress-versus-strain curves for aluminum single crystals. The crystallographic orientation is shown in the stereographic triangle. (Adapted with permission from A. H. Cottrell, Phil. Mag. , 46 (1955) p. 737. )
Radiation Damage Seeger model of damage produced by irradiation. P indicates the position where the first “knock-on” terminates. (Reprinted with permission from A. Seeger, in Proc. Symp. Radiat. Damage Solids React. , Vol. 1, (Vienna, IAEA, 1962) pp. 101, 105. ) Voids formed in nickel irradiated using 400 ke. V 14 N 2+ ions to a dose of 40 dpa at 500 ◦C; notice the voids with polyhedral shape; dpa = displacements per atom. (Courtesy of L. J. Chen and A. J. Ardell. )
Radiation Damage Stress–strain curves for irradiated and unirradiated Zircaloy. (Adapted with permission from J. T. A. Roberts, IEEE Trans. Nucl. Sci. , NS -22, (1975) 2219. )
Radiation Damage Stress-free dilation in AISI 316 steel (20% cold worked). (Adapted with permission from J. T. A. Roberts, IEEE Trans. Nucl. Sci. , NS-22, (1975) 2219. ) Dependence of fast neutron-induced dilation in stainless steel (Fe–Cr–Ni) as a function of Ni and Cr amounts. (Adapted with permission from W. B. Hillig, Science, 191 (1976) 733. )
Line Defects (a) Rug with a fold. Caterpillar with a hump.
Edge and Screw Dislocations Arrangement of atoms in an edge dislocation and the Burgers vector b that produces closure of circuit ABCDE. Arrangement of atoms in a screw dislocation with “parking garage” setup. Notice car entering garage.
Edge and Screw Dislocations . (a) Perfect crystal. (b) Edge dislocation. (c) Screw dislocation.
Plastic Deformation Plastic deformation of a crystal by the movement of a dislocation along a slip plane.
Shear Produced by Dislocation Movement
Mixed Dislocation Mixed dislocation obtained from cutand-shear operation; notice the angle between b and dislocation line.
Dislocations in Metals (a) Titanium. (Courtesy of B. K. Kad. ) (b) Silicon.
Dislocations in Al 2 O 3 and Ti. C Dislocations in (a) Al 2 O 3 and (b) Ti. C. (Courtesy of J. C. La. Salvia. )
Dislocation in Molybdenum Atomic resolution transmission electron micrograph of dislocation in molybdenum with a Burgers circuit around it. (Courtesy of R. Gronsky. )
Square Dislocation Loop
Elliptic Dislocation Loop Elliptic dislocation loop. (a) Intermediate position. (b) Final (sheared) position. (c) TEM of shear loop in copper. (Courtesy of F. Gregori and M. S. Schneider. )
Prismatic Loop Prismatic loop produced by the introduction of a disk into metal. (a) Perspective view. (b) Section AAAA. (c) Section BBBB.
Movement of Dislocation Slip produced by the movement of dislocation. (a) Positive and negative edge dislocations. (b) Positive and negative screw dislocations.
Expansion of a Dislocation Loop
Stresses due to Dislocations Screw Dislocation Edge Dislocation
Stress Fields Around a Edge Dislocation Stress fields around an edge dislocation. (The dislocation line is Ox 3), (a) σ11; (b) σ22; (c) σ33; (d) σ12. (Adapted with permission from J. C. M. Li, in Electron Microscopy and Strength of Crystals, eds. G. Thomas and J. Washburn (New York: Interscience Publishers, 1963). )
Dislocation Array Schematic representation of an idealized dislocation array (a) in two dimensions (b) in three dimensions; note that dislocations on three perpendicular atomic planes define a volume V.
Bending of a Dislocation
Dislocations in an FCC Crystal
Peach-Koehler Equation
Decomposition of Dislocation Decomposition of a dislocation b 1 into two partial dislocations b 2 and b 3, separated by a distance d 0.
Stacking Fault Energies of Some Metals
Stacking Fault and Partial Dislocations Short segment of stacking fault in AISI 304 stainless steel overlapping with coherent twin boundary. Differences in the nature of these defects are illustrated by fringe contrast differences. Dislocations in AISI 304 stainless steel splitting into partials bounded by short stacking-fault region. Partials spacing marked as d. (Courtesy of L. E. Murr. )
Effects of Stacking-Fault Energy on Dislocation Substructure Effect of stacking-fault energy on dislocation substructure. (a) High-stacking-fault-energy material (pure copper); (b) Low-stacking-fault-energy material (copper– 2 wt% aluminum). Both materials were laser-shock compressed with an initial pressure of 40 GPa and pulse duration of 3 ns. (Courtesy of M. S. Schneider. )
Frank or Sessile Dislocations Frank or Sessile dislocations. (a) Intrinsic. (b) Extrinsic.
Cottrell –Lomer and Stairway Dislocations Cottrell–Lomer lock. Stairway dislocation.
Important Planes in HCP Structure Basal, pyramidal, and prism plane in HCP structure.
Temperature for Macroscopic Plasticity in Some Ceramics
Slip Systems and Burgers Vectors in Some Ceramics
Expressions for Energy of Dislocation Screw Dislocation Edge Dislocation General Form
Basal Plane in Al 2 O 3
Elastic Energy for Dislocations in Ceramics
Dislocations in Sapphire (a) Dislocations, dipoles, and loops in sapphire. (b) Interaction between dislocations in sapphire. (From K. P. D. Lagerdorf, B. J. Pletka, T. E. Mitchell, and A. H. Heuer, Radiation Effects, 74 (1983)(. 87
Dislocations in Titanium Diboride Hexagonal array of dislocations in titanium diboride. (Courtesy of D. A. Hoke and G. T. Gray. ) Stacking faults in Ga. P. (Courtesy of P. Pirouz. )
Homogeneous Nucleation of Dislocations
Grain Boundary as a Source of Dislocations Emission of dislocations from ledges in grain boundary, as observed in transmission electron microscopy during heating by electron beam. (Courtesy of L. E. Murr. )
Effect of Oxide Layer on the Tensile Properties of Niobium Effect of oxide layer on the tensile properties of niobium. (Reprinted with permission from V. K. Sethi and R. Gibala, Scripta Met. 9 (1975) 527. )
Frank-Read Mechanism Formation of dislocation loop by the Frank–Read mechanism.
Dislocation Source: Cross Slip Frank–Read source formed by crossslip.
Epitaxial Growth Epitaxial growth of thin film. (a) Substrate. (b) Start of epitaxial growth. (c) Formation of dislocations.
Dislocation Pileups Pileup of dislocations against a barrier. Pileup of dislocations against grain boundaries (or dislocations being emitted from grain boundary sources? ) in copper observed by etch pitting.
Dislocation Interactions (a) Edge dislocation traversing “forest” dislocation. (b) Screw dislocation traversing “forest” dislocations.
Kinks and Jogs in Dislocations (a) Kink and jog in edge dislocation. (b) Kink and jog in screw dislocation. Loop being pinched out when jog is left behind by dislocation motion.
Orowan’s Equation
Peierls-Nabarro Stress (a) Movement of dislocation away from its equilibrium position. (b) Variation of Peierls–Nabarro stress with distance. (Reprinted with permission from H. Conrad, J. Metals, 16 (1964), 583. )
Overcoming of Peierls Barrier Overcoming of Peierls barrier by Seeger kink pair mechanism. (a) Original straight dislocation. (b) Dislocation with two kinks. (c) Kinks moving apart.
Temperature Effect on Young’s Modulus Effect of temperature on Young’s modulus. (Adapted from J. B. Wachtman Jr. , W. E. Tefft, D. G. Lam, Jr. , and C. S. Apstein, J. Res. Natl. Bur. Stand. , 64 A (1960)213; and J. Lemartre and J. L. Chaboche, Mechanics of Solid Materials, Cambridge: Cambridge University Press, 1990, p. 143. )
Flow Stress as a Function of Temperature Flow stress as a function of temperature for (a) an idealized material, (b) BCC metals, and (c) FCC metals. Notice the greater temperature dependence for Ta and Fe (BCC).
Dislocations on Film-Substrate Interface Stresses and dislocations generated at film-substrate interface; (a) Film and substrate with different lattice parameters; (b) elastic (coherent) accommodation of strains by film; (c) elastic + dislocation (semi-coherent) accommodation of strains at a film thickness greater than hc. (Adapted from W. D. Nix, Met. Trans. , 20 A (1989) 2217. )
Critical Film Thickness vs. Atomic Fraction of Ge Critical film thickness as a function of misfit strain; the greater fraction Ge, the greater the misfit stain and the smaller hc. Predictions from van der Merwe Matthews theory; measurements from J. C. Bean, L. C. Feldman, A. T. Fiory, S. Nakahara, and I. K. Robinson, J. Vac. Sci. Technol. A, 2 (1984) 436. (Adapted from W. D. Nix. , Met. Trans. , 20 A (1989) 2216. )
Misfit Dislocation Generation Mechanisms of misfit dislocation generation; (a) Freund mechanism in which a “threading” dislocation preexisting in substrate lays over interface creating misfit dislocation; (b) Nix mechanism, in which a surface source creates half-loops that move toward interface.
- Types of line defects
- Circular motion is one dimensional or two dimensional
- Types of imperfection
- Volume imperfections
- Delayed differentiation and modular design
- Lattice imperfections
- Secondary commission
- Point defects in crystals
- Hassan fareed physics
- Classification of surveying
- Hub and spoke system advantages and disadvantages
- Frankel defect
- Distortion control in welding
- Scar defect in casting
- Distinguish between schottky and frenkel defect
- Shell cleanliness shell soundness shell texture shell shape
- Block essay
- Bubble point test formula
- Points of parity and points of difference
- Vertical pictures
- Congruent vs incongruent melting
- End point and equivalence point
- Formal similarity aba examples
- Far point near point
- Far point and near point
- Astm d6045
- Boiling and melting points
- Classwork 1-1 point line plane answers
- 5 examples of intersecting lines in real life
- Dc load line circuit
- Undefined terms point and line
- Lesson 1 point line and plane
- Gv blacks classification
- Execution defects
- Twinning tablet defects
- Drop core
- Chain sling defects
- Brown classification of maxillary defects
- Ctc en ctq
- Dpmo
- Planer defects
- Physical defects in personality development
- Hemiseptal defects
- Spina bifida
- Artificial defects of timber
- Flow mark defect
- Concrete defects honeycomb
- Butter defects
- Incomplete casting defect
- Birth defects causes
- Endocardial cushion defect
- Timber seasoning
- Waney edge defect in timber
- Enteric film formers
- Defect amplification and removal in software engineering
- Fault is manifestation of
- Learning from defects
- Surface defects examples
- Gravure cylinder defects
- Birth defects
- The extrusion process
- Core defects of diabetes
- Wire drawing defects