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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. Occur when lots of dislocations move.






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






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






4. 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."






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






6. 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.






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






8. These materials are relatively unaffected by magnetic fields.






9. 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.






10. Cracks propagate along grain boundaries.






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






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






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






14. Emitted light is in phase






15. Sigma=ln(li/lo)






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






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






18. 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.






19. 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






20. Heat capacity.....- increases with temperature -for solids it reaches a limiting value of 3R






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






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






24. 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






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






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






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






28. 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






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






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






31. Is analogous to toughness.






32. - 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






33. Different orientation of cleavage planes in grains.






34. 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






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






36. Light Amplification by Stimulated Emission of Radiation






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






38. 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.






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






40. 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






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






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






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






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






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






46. - 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






47. Ohms Law: voltage drop = current * resistance






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






49. 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)






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