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






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






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






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. 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






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






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






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






9. 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)






10. Cracks propagate along grain boundaries.






11. Is analogous to toughness.






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






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






14. 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)






15. 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






16. Undergo extensive plastic deformation prior to failure.






17. 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






18. 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






19. Undergo little or no plastic deformation.






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






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






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






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






24. 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.






25. Plastic means permanent! When a small load is applied - bonds stretch & planes shear. Then when the load is no longer applied - the planes are still sheared.






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






27. 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.






28. 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."






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






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






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






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






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






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






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






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






38. 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.






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






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






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






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






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






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






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






46. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio






47. Ohms Law: voltage drop = current * resistance






48. Width of smallest feature obtainable on Si surface






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






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