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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 when lots of dislocations move.






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






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






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






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






6. Different orientation of cleavage planes in grains.






7. Diffuse image






8. 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






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






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. 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






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






13. 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.






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






15. 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






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






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






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






19. 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






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

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






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






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






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






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






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






27. Ohms Law: voltage drop = current * resistance






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






29. 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






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






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






32. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






33. 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






34. 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






35. 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.






36. High toughness; material resists crack propagation.






37. 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






38. 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."






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






40. Is reflected - absorbed - scattered - and/or transmitted: Io=It+Ia+Ir+Is






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






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






43. 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.






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






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






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

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47. 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)






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






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






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