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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
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  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






2. (sigma)=K(sigma)^n . K = strength coefficient - n = work hardening rate or strain hardening exponent. Large n value increases strength and hardness.






3. A measure of the ease with which a B field can be induced inside a material.






4. Dimples on fracture surface correspond to microcavities that initiate crack formation.






5. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






6. These materials are relatively unaffected by magnetic fields.






7. 1. Fluorescent Lamp - tungstate or silicate coating on inside of tube emits white light due to UV light generated inside the tube. 2. TV screen - emits light as electron beam is scanned back and forth.






8. The size of the material changes with a change in temperature - polymers have the largest values






9. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






10. -> fluorescent light - electron transitions occur randomly - light waves are out of phase with each other.






11. Measures impact energy 1. Strike a notched sample with an anvil 2. Measure how far the anvil travels following impact 3. Distance traveled is related to energy required to break the sample 4. Very high rate of loading. Makes materials more "brittle."






12. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






13. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values






14. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)






15. Heat capacity.....- increases with temperature -for solids it reaches a limiting value of 3R






16. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






17. 1. Metals: Thermal energy puts many electrons into a higher energy state. 2. Energy States: Nearby energy states are accessible by thermal fluctuations.






18. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






19. To build a device - various thin metal or insulating films are grown on top of each other - Evaporation - MBE - Sputtering - CVD (ALD)






20. Increase temperature - no increase in interatomic separation - no thermal expansion






21. 1. Tc= critical temperature- if T>Tc not superconducting 2. Jc= critical current density - if J>Jc not superconducting 3. Hc= critical magnetic field - if H > Hc not superconducting






22. A parallel-plate capacitor involves an insulator - or dielectric - between two metal electrodes. The charge density buildup at the capacitor surface is related to the dielectric constant of the material.






23. Sigma=ln(li/lo)






24. Light Amplification by Stimulated Emission of Radiation






25. These materials are "attracted" to magnetic fields.






26. Stress concentration at a crack tips






27. Width of smallest feature obtainable on Si surface






28. 1. Ability of the material to absorb energy prior to fracture 2. Short term dynamic stressing - Car collisions - Bullets - Athletic equipment 3. This is different than toughness; energy necessary to push a crack (flaw) through a material 4. Useful in






29. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






30. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by






31. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






32. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






33. Specific heat = energy input/(mass*temperature change)






34. 1. Hard disk drives (granular/perpendicular media) 2. Recording tape (particulate media)






35. Because of ionic & covalent-type bonding.






36. Loss of image transmission - You get no image - There is no light transmission - and therefore reflects - scatters - or absorbs ALL of it. Both mirrors and carbon black are opaque.






37. Materials change size when temperature is changed






38. ...occurs in bcc metals but not in fcc metals.






39. Cracks pass through grains - often along specific crystal planes.






40. The Magnetization of the material - and is essentially the dipole moment per unit volume. It is proportional to the applied field. Xm is the magnetic susceptibility.






41. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






42. Different orientation of cleavage planes in grains.






43. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






44. Ability to transmit a clear image - The image is clear.






45. Second phase particles with n > glass.






46. Another optical property - Depends on the wavelength of the visible spectrum.






47. Increase temperature - increase in interatomic separation - thermal expansion






48. Impurities added to the semiconductor that contribute to excess electrons or holes. Doping = intentional impurities.






49. Reflectiviy is between 0.90 and 0.95 - Metal surfaces appear shiny - Most of absorbed light is reflected at the same wavelength (NO REFRACTION) - Small fraction of light may be absorbed - Color of reflected light depends on wavelength distribution of






50. As the applied field (H) increases the magnetic domains change shape and size by movement of domain boundaries.