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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.
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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. Not ALL the light is refracted - SOME is reflected. Materials with a high index of refraction also have high reflectance - High R is bad for lens applications - since this leads to undesirable light losses or interference.






2. Is analogous to toughness.






3. - A magnetic field is induced in the material B= Magnetic Induction (tesla) inside the material mu= permeability of a solid






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






5. 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






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






7. Becomes harder (more strain) to stretch (elongate)






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






9. Ohms Law: voltage drop = current * resistance






10. Wet: isotropic - under cut Dry: ansiotropic - directional






11. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






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






13. 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."






14. Diffuse image






15. 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






16. They are used to assess properties of ceramics & glasses.






17. Energy is stored as atomic vibrations - As temperature increases - the average energy of atomic vibrations increases.






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






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






20. 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)






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






22. Second phase particles with n > glass.






23. 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.






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






25. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






26. 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






27. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






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






29. Rho=F/A - tau=G/A . Depending on what angle the force is applied - and what angle the crystal is at - it takes different amounts of force to induce plastic deformation.






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






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






32. These materials are relatively unaffected by magnetic fields.






33. The ability of a material to absorb heat - Quantitatively: The energy required to produce a unit rise in temperature for one mole of a material.






34. 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.






35. 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






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






37. Light Amplification by Stimulated Emission of Radiation






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

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






40. 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






41. There is always some statistical distribution of flaws or defects.






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






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






44. Width of smallest feature obtainable on Si surface






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






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






47. 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






48. 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






49. A high index of refraction (n value) allows for multiple internal reactions.






50. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB