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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. - 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






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






3. High toughness; material resists crack propagation.






4. 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






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






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






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






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






9. Process by which geometric patterns are transferred from a mask (reticle) to a surface of a chip to form the device.






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






11. Allows flow of electrons in one direction only (useful to convert alternating current to direct current) - Result: no net current flow






12. 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)






13. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION

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






15. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






16. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is






17. Allows you to calculate what happened G=F' x cos(lambda) - F=F' x cos(phi)






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






19. 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






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






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






22. 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






23. These materials are relatively unaffected by magnetic fields.






24. 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.






25. Materials change size when temperature is changed






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






27. 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






28. 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)






29. Because of ionic & covalent-type bonding.






30. Is analogous to toughness.






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






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






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






34. 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.






35. 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.






36. Specular: light reflecting off a mirror (average) - Diffuse: light reflecting off a white wall (local)






37. 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






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






39. Different orientation of cleavage planes in grains.






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






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






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






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






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






45. This strength parameter is similar in magnitude to a tensile strength. Fracture occurs along the outermost sample edge - which is under a tensile load.






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






47. Failure under cyclic stress 1. It can cause part failure - even though (sigma)max < (sigma)c 2. Causes ~90% of mechanical engineering failures.






48. Without passing a current a continually varying magnetic field will cause a current to flow






49. 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






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