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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 extensive plastic deformation prior to failure.






2. Stress concentration at a crack tips






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






4. 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.






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






6. Ohms Law: voltage drop = current * resistance






7. Diffuse image






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






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






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






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






12. Occur when lots of dislocations move.






13. 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.






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






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






16. Light Amplification by Stimulated Emission of Radiation






17. 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






18. 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.






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






20. - 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






21. Cracks propagate along grain boundaries.






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






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






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






25. Different orientation of cleavage planes in grains.






26. High toughness; material resists crack propagation.






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






28. 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






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






30. Materials change size when temperature is changed






31. 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.






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






33. Occurs at a single pore or other solid by refraction n = 1 for pore (air) n > 1 for the solid - n ~ 1.5 for glass - Scattering effect is maximized by pore/particle size within 400-700 nm range - Reason for Opacity in ceramics - glasses and polymers.






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






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






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






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






38. 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






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






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






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

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42. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






43. A high index of refraction (n value) allows for multiple internal reactions.






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






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






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






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






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






49. 1. Ductility- % elongation - % reduction in area - may be of use in metal forming operations (e.g. - stretch forming). This is convenient for mechanical testing - but not very meaningful for most deformation processing. 2. Toughness- Area beneath str






50. 1. General yielding occurs if flaw size a < a(critical) 2. Catastrophic fast fracture occurs if flaw size a > a(critical)