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






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






3. Sigma=ln(li/lo)






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






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






6. Undergo little or no plastic deformation.






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






8. 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






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






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






11. 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.






12. 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






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






14. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by






15. 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.






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






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






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






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






21. 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






22. These materials are relatively unaffected by magnetic fields.






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






24. Cracks propagate along grain boundaries.






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






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

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27. High toughness; material resists crack propagation.






28. - 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






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






30. Because of ionic & covalent-type bonding.






31. Is analogous to toughness.






32. 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






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






34. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW






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






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






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






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






39. Light Amplification by Stimulated Emission of Radiation






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






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






42. 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."






43. 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.






44. 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






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






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






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






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






49. Diffuse image






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