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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. Undergo little or no plastic deformation.






2. 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






3. 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






4. 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






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






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


7. 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






8. 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






9. Sigma=ln(li/lo)






10. 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.






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






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






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






14. 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






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






16. Hardness is the resistance of a material to deformation by indentation - Useful in quality control - Hardness can provide a qualitative assessment of strength - Hardness cannot be used to quantitatively infer strength or ductility.






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






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






19. Materials change size when temperature is changed






20. Because of ionic & covalent-type bonding.






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






22. Emitted light is in phase






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






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






25. 1. Tc= critical temperature- if T>Tc not superconducting 2. Jc= critical current density - if J>Jc not superconducting 3. Hc= critical magnetic field - if H > Hc not superconducting






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






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






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






29. - 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






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






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


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






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






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






35. 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.






36. 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






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






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






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






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






41. Ohms Law: voltage drop = current * resistance






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






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






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






45. 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.






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






47. Stress concentration at a crack tips






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






49. Undergo extensive plastic deformation prior to failure.






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