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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. Different orientation of cleavage planes in grains.






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






3. Is analogous to toughness.






4. 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)






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






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






7. 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






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






9. A parallel-plate capacitor involves an insulator - or dielectric - between two metal electrodes. The charge density buildup at the capacitor surface is related to the dielectric constant of the material.






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






11. Another optical property - Depends on the wavelength of the visible spectrum.






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






13. Large coercivities - Used for permanent magnets - Add particles/voids to inhibit domain wall motion - Example: tungsten steel






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






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






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






17. 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






18. 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






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






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






21. 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






22. Because of ionic & covalent-type bonding.






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






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






25. Width of smallest feature obtainable on Si surface






26. 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






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






28. 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






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






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






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






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






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






34. 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.






35. Undergo extensive plastic deformation prior to failure.






36. Cracks pass through grains - often along specific crystal planes.






37. Materials change size when temperature is changed






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






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






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






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






42. High toughness; material resists crack propagation.






43. If a material has ________ - then the field generated by those moments must be added to the induced field.






44. Sigma=ln(li/lo)






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






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






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






48. 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






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






50. 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.







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