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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. Stress-strain behavior is not usually determined via tensile tests 2. Material fails before it yields 3. Bend/flexure tests are often used instead.






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






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






4. 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.






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






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






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






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






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






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






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






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






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






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






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






17. 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."






18. Materials change size when temperature is changed






19. 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






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






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






22. 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






23. 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






24. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






25. Different orientation of cleavage planes in grains.






26. Width of smallest feature obtainable on Si surface






27. 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.






28. 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






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






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






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






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






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






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






35. 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)






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






37. - 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






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






39. 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.






40. Light Amplification by Stimulated Emission of Radiation






41. Occur when lots of dislocations move.






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






43. 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.






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






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






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






47. 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






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






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






50. 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.