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






2. High toughness; material resists crack propagation.






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






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






5. 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."






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






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






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

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9. 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






10. 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






11. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






12. 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)






13. Second phase particles with n > glass.






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






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






16. Stress concentration at a crack tips






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






18. Emitted light is in phase






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






20. These materials are relatively unaffected by magnetic fields.






21. The ability of a material to be rapidly cooled and not fracture






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






23. 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






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






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






26. 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






27. Different orientation of cleavage planes in grains.






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






29. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






30. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






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






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






33. 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.






34. Cracks propagate along grain boundaries.






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






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






37. 1. Fluorescent Lamp - tungstate or silicate coating on inside of tube emits white light due to UV light generated inside the tube. 2. TV screen - emits light as electron beam is scanned back and forth.






38. Sigma=ln(li/lo)






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






40. Diffuse image






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






42. 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






43. 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.






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






45. 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






46. 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






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






48. Undergo extensive plastic deformation prior to failure.






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






50. Is analogous to toughness.