1. DLD - DECODER 1 NAMEENROLLMENT NO. PARMAR STANY140070119051 PATEL ARJUN140070119052 PATEL KAMAL140070119053 PATEL KRUNAL140070119054 GUIDED BY: PROF. R.R.PATEL & PROF. S.P.JOSHI

2. LEVEL OF STRUCTURE AND STRUCTURE PROPERTY RELATIONSHIPS

3. LEVEL OF STRUCTURE Macrostructure Microstructure Substructure Crystal structure Electronic structure Nuclear structure

4. Macrostructure -Examined with naked eye or low magnification physical aid. -Length of scale is ( ~>10 -4 ). -Porosity, surface coatings, internal or external cracks, fracture surfaces, slag inclusions, materials flow lines, segregation, heat affected zone can be observed.

5. Microstructure -Observed under optical microscope. -Microscope can magnify structure about 1500 times, without loss of resolution. -Microscope resolve upto 10 -7 m. -Length of scale is (10nm to 1000nm). -Grain (size,shape,orientation), grain boundaries, inclusions, relative amount of phases, mechanical or thermal history of material can be observed.

6. OPTICAL MICROSCOPE VIEW OF MICROSTRUCTURE AND GRAIN BOUNDARIES

7. Substructure -Observed by using higher magnification microscope like electron microscope. -Magnification is 10 6 times the linear. -Much finer details is shown up due to very small wavelength of electrons. -Length of scale is upto (10 -10 m). -Very fine particles or crystal imperfections like dislocations can be observed. -Field ion microscope also can be used for observation of individual atoms or arrangements.

8. ELECTRON MICROSCOPE OUTPUT VIEW OF ELECTRON MIROSCOPE (IMPERFACTIONS)

9. Crystal structure -Provides detail of the atomic arrangements within a crystal. -Arrangement of few atoms which is repeatedly in whole crystal called unit cell. -Few atomic arrangements are…. Bcc, fcc, hcp

11. Elecronic structure -Refers to the electrones in outer most orbital of individual atoms making solid. -Spectroscopic techniques are used -Provide information about as electrical properties, magnetic properties, optical properties, chemical properties. Nuclear structure -Studied by spectroscopic techniques like nuclear magnetic resonance, Mossbauer studies.

12. STRUCTURE PROPERTY RELATIONSHIPS All solid atoms are held together by bonds, it provide strength, electrical and thermal properties. Example: strong bond lead to high melting temperature, high mduli of elasticity, shorter interatomic distance and lower thermal expansion coefficients. Atomic structure is described by electronic configuration or energy levels. Valance electron correlated to electrical and thermal conductivity.

13. While bonding there are attractive and repulsive forces are between two atoms. At some point forces are equal and opposite. Net force = 0 Energy is lowest at that point Bonding occurs It’s a most stable condition

14. As shown in figure… Net force = 0 at point (m). Hence, energy is lowest (point ‘c’) Bonding occurs with ‘om’ atomic radius Bonding occurs only at most stable position.

15. Melting point and boiling point can be correlated with depth of energy trough. (‘Mc’ in figure-1) Hence, high depth of energy trough…. -High melting point and -high boiling point And small depth of energy trough it will become low

16. Strength is influenced by height of total force. Cross sectional area under total force curve gives…. Stress required to separate atoms. (means strength of material) However, strength is still governed by interatomic forces Larger interatomic forces of attraction imply deeper energy troughs. (High melting point)

17. Materials with high melting points are often harder materials. Examples: diamond, alumina In contrast…. -Materials with weaker bonds there is a correlation between softness and low melting point. -Examples: lead, plastics, ice, grease

18. Modulus of elasticity is correlated with slope of sum curve At equilibrium distance (net force=0) slope of curve relates stress to strain. Thermal expansion depends upon… The depth and symmetry of energy trough.

19. Graph shows energy vs. distance graph while bonding occurs in ‘nacl’. Net force=0 at r 0 HENCE LOWEST ENERGY AT INTER ATOMIC DISTANCE 236pm. High energy trough hence high strength of bonding.

20. Thank you