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






2. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






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






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






5. 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






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






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






8. Occur when lots of dislocations move.






9. Sigma=ln(li/lo)






10. 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.






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






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






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






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






15. 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."






16. Second phase particles with n > glass.






17. 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






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. Width of smallest feature obtainable on Si surface






20. Materials change size when temperature is changed






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






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






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






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






25. 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.






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






27. 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






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






29. 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






30. These materials are relatively unaffected by magnetic fields.






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






32. Cracks propagate along grain boundaries.






33. 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






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






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






36. 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.






37. 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.






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






39. 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






40. - 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






41. High toughness; material resists crack propagation.






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






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. 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






45. Ohms Law: voltage drop = current * resistance






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






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






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






49. Undergo little or no plastic deformation.






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