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






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






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






4. 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.






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






6. 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.






7. Undergo extensive plastic deformation prior to failure.






8. Second phase particles with n > glass.






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






10. - Metals that exhibit high ductility - exhibit high toughness. Ceramics are very strong - but have low ductility and low toughness - Polymers are very ductile but are not generally very strong in shear (compared to metals and ceramics). They have low






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. Undergo little or no plastic deformation.






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






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






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






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






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






18. Emitted light is in phase






19. 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)






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






21. 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






22. Sigma=ln(li/lo)






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. 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






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






26. 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






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






28. Width of smallest feature obtainable on Si surface






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






30. Light Amplification by Stimulated Emission of Radiation






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






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






33. Materials change size when temperature is changed






34. 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






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






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






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






38. 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.






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






40. - 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






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






42. 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






43. Different orientation of cleavage planes in grains.






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

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






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






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






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






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






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