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






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






3. - 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






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






5. 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






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






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






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






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






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






13. Undergo extensive plastic deformation prior to failure.






14. - 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






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






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






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






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






19. 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






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






21. High toughness; material resists crack propagation.






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






23. Ohms Law: voltage drop = current * resistance






24. Stress concentration at a crack tips






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


26. 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






27. 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.






28. 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






29. 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.






30. 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






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






32. Width of smallest feature obtainable on Si surface






33. Different orientation of cleavage planes in grains.






34. Sigma=ln(li/lo)






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






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






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






38. Is analogous to toughness.






39. Cracks propagate along grain boundaries.






40. Diffuse image






41. 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.






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






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


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






45. Light Amplification by Stimulated Emission of Radiation






46. Emitted light is in phase






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






48. 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






49. 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.






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