🗊Презентация Imperfections in Solids

Категория: Химия
Нажмите для полного просмотра!
Imperfections in Solids, слайд №1Imperfections in Solids, слайд №2Imperfections in Solids, слайд №3Imperfections in Solids, слайд №4Imperfections in Solids, слайд №5Imperfections in Solids, слайд №6Imperfections in Solids, слайд №7Imperfections in Solids, слайд №8Imperfections in Solids, слайд №9Imperfections in Solids, слайд №10Imperfections in Solids, слайд №11Imperfections in Solids, слайд №12Imperfections in Solids, слайд №13Imperfections in Solids, слайд №14Imperfections in Solids, слайд №15Imperfections in Solids, слайд №16Imperfections in Solids, слайд №17Imperfections in Solids, слайд №18Imperfections in Solids, слайд №19Imperfections in Solids, слайд №20Imperfections in Solids, слайд №21Imperfections in Solids, слайд №22Imperfections in Solids, слайд №23Imperfections in Solids, слайд №24Imperfections in Solids, слайд №25Imperfections in Solids, слайд №26Imperfections in Solids, слайд №27Imperfections in Solids, слайд №28Imperfections in Solids, слайд №29Imperfections in Solids, слайд №30Imperfections in Solids, слайд №31Imperfections in Solids, слайд №32Imperfections in Solids, слайд №33Imperfections in Solids, слайд №34
Скачать
Вы можете ознакомиться и скачать презентацию на тему Imperfections in Solids. Доклад-сообщение содержит 34 слайдов. Презентации для любого класса можно скачать бесплатно. Если материал и наш сайт презентаций Mypresentation Вам понравились – поделитесь им с друзьями с помощью социальных кнопок и добавьте в закладки в своем браузере.

Слайды и текст этой презентации

Слайд 1


Chapter 4: Imperfections in Solids
Описание слайда:
Chapter 4: Imperfections in Solids

Слайд 2


Imperfections in Solids Solidification- result of casting of molten material 2 steps Nuclei form Nuclei grow to form crystals – grain structure Start with a molten material – all liquid
Описание слайда:
Imperfections in Solids Solidification- result of casting of molten material 2 steps Nuclei form Nuclei grow to form crystals – grain structure Start with a molten material – all liquid

Слайд 3


Polycrystalline Materials Grain Boundaries regions between crystals transition from lattice of one region to that of the other slightly disordered low density in grain boundaries high mobility high diffusivity high chemical reactivity
Описание слайда:
Polycrystalline Materials Grain Boundaries regions between crystals transition from lattice of one region to that of the other slightly disordered low density in grain boundaries high mobility high diffusivity high chemical reactivity

Слайд 4


Solidification Grains can be - equiaxed (roughly same size in all directions) - columnar (elongated grains)
Описание слайда:
Solidification Grains can be - equiaxed (roughly same size in all directions) - columnar (elongated grains)

Слайд 5


Imperfections in Solids There is no such thing as a perfect crystal. What are these imperfections? Why are they important? Many of the important properties of materials are due to the presence of imperfections.
Описание слайда:
Imperfections in Solids There is no such thing as a perfect crystal. What are these imperfections? Why are they important? Many of the important properties of materials are due to the presence of imperfections.

Слайд 6


Types of Imperfections
Описание слайда:
Types of Imperfections

Слайд 7


Point Defects in Metals
Описание слайда:
Point Defects in Metals

Слайд 8


Equilibrium Concentration: Point Defects
Описание слайда:
Equilibrium Concentration: Point Defects

Слайд 9


Measuring Activation Energy
Описание слайда:
Measuring Activation Energy

Слайд 10


Estimating Vacancy Concentration
Описание слайда:
Estimating Vacancy Concentration

Слайд 11


Observing Equilibrium Vacancy Conc.
Описание слайда:
Observing Equilibrium Vacancy Conc.

Слайд 12


Imperfections in Metals (i)
Описание слайда:
Imperfections in Metals (i)

Слайд 13


Imperfections in Metals (ii) Conditions for substitutional solid solution (S.S.) W. Hume – Rothery rule 1. r (atomic radius) < 15% 2. Proximity in periodic table i.e., similar electronegativities 3. Same crystal structure for pure metals 4. Valency All else being equal, a metal will have a greater tendency to dissolve a metal of higher valency than one of lower valency
Описание слайда:
Imperfections in Metals (ii) Conditions for substitutional solid solution (S.S.) W. Hume – Rothery rule 1. r (atomic radius) < 15% 2. Proximity in periodic table i.e., similar electronegativities 3. Same crystal structure for pure metals 4. Valency All else being equal, a metal will have a greater tendency to dissolve a metal of higher valency than one of lower valency

Слайд 14


Imperfections in Metals (iii) Application of Hume–Rothery rules – Solid Solutions 1. Would you predict more Al or Ag to dissolve in Zn? 2. More Zn or Al in Cu?
Описание слайда:
Imperfections in Metals (iii) Application of Hume–Rothery rules – Solid Solutions 1. Would you predict more Al or Ag to dissolve in Zn? 2. More Zn or Al in Cu?

Слайд 15


Impurities in Solids Specification of composition weight percent
Описание слайда:
Impurities in Solids Specification of composition weight percent

Слайд 16


Line Defects
Описание слайда:
Line Defects

Слайд 17


Imperfections in Solids Linear Defects (Dislocations) Are one-dimensional defects around which atoms are misaligned Edge dislocation: extra half-plane of atoms inserted in a crystal structure b perpendicular () to dislocation line Screw dislocation: spiral planar ramp resulting from shear deformation b parallel () to dislocation line
Описание слайда:
Imperfections in Solids Linear Defects (Dislocations) Are one-dimensional defects around which atoms are misaligned Edge dislocation: extra half-plane of atoms inserted in a crystal structure b perpendicular () to dislocation line Screw dislocation: spiral planar ramp resulting from shear deformation b parallel () to dislocation line

Слайд 18


Imperfections in Solids Edge Dislocation
Описание слайда:
Imperfections in Solids Edge Dislocation

Слайд 19


Motion of Edge Dislocation
Описание слайда:
Motion of Edge Dislocation

Слайд 20


Imperfections in Solids Screw Dislocation
Описание слайда:
Imperfections in Solids Screw Dislocation

Слайд 21


VMSE: Screw Dislocation In VMSE: a region of crystal containing a dislocation can be rotated in 3D dislocation motion may be animated
Описание слайда:
VMSE: Screw Dislocation In VMSE: a region of crystal containing a dislocation can be rotated in 3D dislocation motion may be animated

Слайд 22


Edge, Screw, and Mixed Dislocations
Описание слайда:
Edge, Screw, and Mixed Dislocations

Слайд 23


Imperfections in Solids Dislocations are visible in electron micrographs
Описание слайда:
Imperfections in Solids Dislocations are visible in electron micrographs

Слайд 24


Dislocations & Crystal Structures
Описание слайда:
Dislocations & Crystal Structures

Слайд 25


Planar Defects in Solids One case is a twin boundary (plane) Essentially a reflection of atom positions across the twin plane. Stacking faults For FCC metals an error in ABCABC packing sequence Ex: ABCABABC
Описание слайда:
Planar Defects in Solids One case is a twin boundary (plane) Essentially a reflection of atom positions across the twin plane. Stacking faults For FCC metals an error in ABCABC packing sequence Ex: ABCABABC

Слайд 26


Catalysts and Surface Defects A catalyst increases the rate of a chemical reaction without being consumed Active sites on catalysts are normally surface defects
Описание слайда:
Catalysts and Surface Defects A catalyst increases the rate of a chemical reaction without being consumed Active sites on catalysts are normally surface defects

Слайд 27


Microscopic Examination Crystallites (grains) and grain boundaries. Vary considerably in size. Can be quite large. ex: Large single crystal of quartz or diamond or Si ex: Aluminum light post or garbage can - see the individual grains Crystallites (grains) can be quite small (mm or less) – necessary to observe with a microscope.
Описание слайда:
Microscopic Examination Crystallites (grains) and grain boundaries. Vary considerably in size. Can be quite large. ex: Large single crystal of quartz or diamond or Si ex: Aluminum light post or garbage can - see the individual grains Crystallites (grains) can be quite small (mm or less) – necessary to observe with a microscope.

Слайд 28


Optical Microscopy
Описание слайда:
Optical Microscopy

Слайд 29


Optical Microscopy
Описание слайда:
Optical Microscopy

Слайд 30


Optical Microscopy Polarized light metallographic scopes often use polarized light to increase contrast Also used for transparent samples such as polymers
Описание слайда:
Optical Microscopy Polarized light metallographic scopes often use polarized light to increase contrast Also used for transparent samples such as polymers

Слайд 31


Microscopy Optical resolution ca. 10-7 m = 0.1 m = 100 nm For higher resolution need higher frequency X-Rays? Difficult to focus. Electrons wavelengths ca. 3 pm (0.003 nm) (Magnification - 1,000,000X) Atomic resolution possible Electron beam focused by magnetic lenses.
Описание слайда:
Microscopy Optical resolution ca. 10-7 m = 0.1 m = 100 nm For higher resolution need higher frequency X-Rays? Difficult to focus. Electrons wavelengths ca. 3 pm (0.003 nm) (Magnification - 1,000,000X) Atomic resolution possible Electron beam focused by magnetic lenses.

Слайд 32


Scanning Tunneling Microscopy (STM)
Описание слайда:
Scanning Tunneling Microscopy (STM)

Слайд 33


Summary
Описание слайда:
Summary

Слайд 34


ANNOUNCEMENTS
Описание слайда:
ANNOUNCEMENTS

Скачать

Похожие презентации
Mypresentation.ru
Загрузить презентацию