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

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






3. 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.






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






5. Dimples on fracture surface correspond to microcavities that initiate crack formation.






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






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






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






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






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






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






12. Is analogous to toughness.






13. Light Amplification by Stimulated Emission of Radiation






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






15. 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






16. Cracks propagate along grain boundaries.






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

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






19. 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






20. - 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






21. 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)






22. 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."






23. 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






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






25. Diffuse image






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






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






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






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






30. Emitted light is in phase






31. Ohms Law: voltage drop = current * resistance






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






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






34. 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






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






36. 1. Necking 2. Cavity formation 3. Cavity coalescence to form cracks 4. Crack propagation (growth) 5. Fracture






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






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






39. 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.






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






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






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






43. 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)






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






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






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






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






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






49. 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.






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