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






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






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






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






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






8. Second phase particles with n > glass.






9. 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.






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






11. 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.






12. Width of smallest feature obtainable on Si surface






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






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






15. Is analogous to toughness.






16. 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.






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






18. 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






19. 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






20. 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






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






22. 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






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






24. - 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






25. 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.






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






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






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






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






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






31. 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)






32. 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.






33. 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."






34. Different orientation of cleavage planes in grains.






35. Emitted light is in phase






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






37. Undergo extensive plastic deformation prior to failure.






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






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






40. 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.






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






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






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






44. 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






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






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






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






48. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio






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






50. 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