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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • 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. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






2. Cracks propagate along grain boundaries.






3. The ability of a material to be rapidly cooled and not fracture






4. # of thermally generated electrons = # of holes (broken bonds)






5. Is analogous to toughness.






6. Occur due to: restrained thermal expansion/contraction -temperature gradients that lead to differential dimensional changes sigma = Thermal Stress






7. Found in 26 metals and hundreds of alloys & compounds - Tc= critical temperature = termperature below which material is superconductive.






8. For a metal - there is no ______ - only reflection






9. Typical loading conditions are _____ enough to break all inter-atomic bonds






10. These materials are relatively unaffected by magnetic fields.






11. 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






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






13. 1. Electron motions 2. The spins on electrons - Net atomic magnetic moment: sum of moments from all electrons.






14. Occur when lots of dislocations move.






15. 1. Impose a compressive surface stress (to suppress surface cracks from growing) - Method 1: shot peening - Method 2: carburizing 2.Remove stress concentrators.






16. Elastic means reversible! This is not a permanent deformation.






17. Materials change size when temperature is changed






18. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






19. 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)






20. Small Coercivities - Used for electric motors - Example: commercial iron 99.95 Fe






21. Resistance to plastic deformation of cracking in compression - and better wear properties.






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






23. Liquid polymer at room T - sandwiched between two sheets of glass - coated with transparent - electrically conductive film. - Character forming letters/ numbers etched on the face - Voltage applied disrupts the orientation of the rod- shaped molecule






24. 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.






25. Metals are good conductors since their _______is only partially filled.






26. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






27. Different orientation of cleavage planes in grains.






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






29. 1. Stress-strain behavior is not usually determined via tensile tests 2. Material fails before it yields 3. Bend/flexure tests are often used instead.






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






31. 1. Tensile (opening) 2. Sliding 3. Tearing






32. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






33. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






34. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






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






36. Emitted light is in phase






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






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






39. The magnetic hysteresis phenomenon: Stage 1: Initial (unmagnetized state) Stage 2: Apply H - align domains Stage 3: Remove H - alignment remains => Permanent magnet Stage 4: Coercivity - Hc negative H needed to demagnitize Stage 5: Apply -H - align d






40. If a material has ________ - then the field generated by those moments must be added to the induced field.






41. Because of ionic & covalent-type bonding.






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






43. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)






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






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






46. Undergo little or no plastic deformation.






47. Second phase particles with n > glass.






48. Diffuse image






49. Process by which metal atoms diffuse because of a potential.






50. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.

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