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mse
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2013-04-29 08:23:20
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  1. To further increase the elastic modulus of the steel sword blade, the Japanese masters would
    fold the steel 15 times to obtain 30,000 layers in the blade
  2. The samurai sword is made by folding the steel blade during fabrication resulting in approximately how many internal layers:
    30,000
  3. If you would pick an elastic modulus for the Samurai Sword, it would be nearest which of the following:
    piano wire (because the samurai sword is mild steel)
  4. The Roman Empire and later the Venetians were masters of, and greatly advanced, which of the following materials listed on the plot?
    Glass
  5. Which of the following materials has the lowest Young's modulus?
    Glass (because its slope is the lowest)
  6. Examine the elastic behavior for glass. The yield point (fracture point in this case) for glass is very low considering it is dominated by covalent bonds. Why is this so?
    because the surfaces are full of small cracks (scratches)
  7. Which of the following has a body centered cubic atomic structure: bronze, ferrite, austenite, cementite?
    ferrite
  8. Ferrite is
    alpha-iron, or pure iron, with a body-centered cubic crystal structure. It is this crystalline structure which gives steel and cast iron their magnetic properties
  9. The development of glass technology had to wait for
    the development of iron to make a blowpipe that could withstand the high temperatures
  10. All the glass surfaces contain small cracks, which can lead to easy fracture. This is despite the intrinsic strength of glass due to __ bonds.
    Covalent
  11. The windscreen in your automobile overcomes this problem of small surface cracks by placing the windscreen surfaces in a state of ___
    compression
  12. Most silica glasses that you come in contact with have this atomic structure: __ with __ range order
    Amorphous with short range order
  13. The glass transition, T sub g, is:
    the temperature below which a glass is considered to be a solid
  14. The reason to anneal the glass is __
    to remove stresses within the object caused by uneven cooling from the working range.
  15. A perpetual motion machine that produces more energy than it takes to run its is a violation of primarily which law of thermodynamics? Conservation of energy--can't produce more energy than it goes into the machine.
    First law
  16. Energy dissipation is described by which law of Thermodynamics
    Second law
  17. The direction a process will go when it occurs with no human intervention is an example of which law of thermodynamics?
    Second law
  18. The composition of the Japanese sword is near 99% iron -- 1% carbon (written: Fe-1.0%C). When heated to 1400 degrees Celsius the phase present are:
    austenite + liquid
  19. At 600 degree Celsius the alloy Fe-1.0%C contains what amount of cementite?
    15%
  20. The ideal Samurai sword contains only which two final microstructures?
    bainite + martensite
  21. "Scythes are quenched cherry red" This color ensures the tool is cooled from what phase(s)?
    austenite
  22. Which phases in piano wire allow dislocations to move?
    Austenite, ferrite, bainite, pearlite
  23. Why would material scientists want to manipulate the microstructure of a material?
    By manipulating the micro structural features, one can make materials with new, more wanted properties, or combinations of desired properties.
  24. What are 'crystal gains'?
    Volume elements of uniform lattice orientation that are joined to similar volume elements but with different lattice orientations
  25. Why are x-rays, rather than visible light, used in determining the structure of crystals such as iron or copper?
    To investigate the atomic structure, the wavelength of the radiation must be about the same or less than what you're examining
  26. Materials are frequently classified as either as crystalline or non-crystalline. The characteristic which determines whether a material is crystalline or not is the presence or absence of
    • 1. Electrons that are not bound to atoms
    • 2. Long-range periodicty
  27. What is the Rayleigh's Law for resolution?
    The minimum spacing that we can see (resolve) d is given by: d = 0.61 lambda, where lambda is the wavelength of the radiation used during observation.
  28. Hardness
    resistance to plastic deformation (e.g., a local dent or scratch). Thus, it is a measure of plastic deformation, as is the tensile strength, so they are well correlated. Historically, it was measured on an empirically scale, determined by the ability of a material to scratch another, diamond being the hardest and talc the softer.
  29. Yield point
    If the stress is too large, the strain deviates from being proportional to the stress. The point at which this happens is the yield point because there the material yields, deforming permanently (plastically).
  30. Yield stress
    Hooke's law is not valid beyond the yield point. The stress at the yield point is called yield stress, and is an important measure of the mechanical properties of materials. In practice, the yield stress is chosen as that causing a permanent strain of 0.002

    The yield stress measures the resistance to plastic deformation
  31. Tensile strength
    When stress continues in the plastic regime, the stress-strain passes through a maximum, called the tensile strength (sTS) , and then falls as the material starts to develop a neck and it finally breaks at the fracture point.

    Note that it is called strength, not stress, but the units are the same, MPa
  32. Toughness
    Ability to absorb energy up to fracture. The energy per unit volume is the total area under the strain-stress curve. It is measured by an impact test
  33. Crystalline alloys
    Atoms arranged in a periodic pattern which repeats over millions or trillions of atoms
  34. How do materials deform?
    Rows of atoms slide over another just liek the cards in a deck when you push them from aside
  35. What prevents atoms in an alloy from sliding?
    Grain boundaries in discontinuities that prevent the planes of atoms from sliding, which strengthen the alloy
  36. Diffraction only occurs when
    condition for constructive interference is satisfied
  37. Braggs Law
    nλ = 2dsinθ

    d is the distance between atomic layers in a crystal

    λ is the wavelength of the incident X-ray beam

    n is an integer
  38. Piano (Music) Wire
    Piano wire has rightly been called the "specialty of specialties". It represents the highest attainment in the art of wire manufacture. In addition to the mechanical properties required, piano wire must possess acoustic properties. It is the strongest engineering material available in commercialquantities. Drawn pearlite steel wire is made to a carbon content between 0.80 and 1.00 w/o.
  39. Steelmaking
    Pig iron consists of the element iron combined with numerous other chemical elements, the most common of which are carbon, manganese, phosphorus, sulphur, and silicon. In refining pig iron to convert it into steel, all five of these elements must be either removed almost entirely or at least reduced drastically in amount.Pneumatic Steelmaking (developed by Kelly & Bessemer)The fundamental principle is that the oxidation of the major impurities in liquid blast-furnace iron (Si, Mn, C) would be preferentially oxidized before the major oxidation or iron (Fig. 7).The Basic Oxygen Steelmaking Process (or BOP), (the furnace in which the process is carried out is referred to as the BOF) uses oxygen of high purity which is blown at high velocity onto the surface of the bath.
  40. Blast Furnace and Pig Iron
    Pig iron is the term applied generally to the metallic product of the blast furnace when it contains over 90 percent iron. Most pig iron is transferred to the steel-making shops and used in the liquid state; in this form it is referred to as hot metal. The term "pig iron" arose from the old-fashioned method of casting iron into beds of molds form in sand, so arranged that they could be fed from a common runner. Since the group of molds resembled a litter of suckling pigs, the individual pieces of iron were referred to as "pigs" and the runner as a "sow".In the blast-furnace process, iron-bearing materials, such as iron ore, sinter, pellets, along with fuel (coke), and flux (limestone) are charged into the top of the furnace (Fig. 6). Heated air (blast) and, in some instances, fuel (gas, oil or powdered coal) are blown in at the bottom. The blast air burns part of the fuel to produce heat for the chemical reactions involved and for melting the iron, while the balance of the fuel and part of the gas from the combustion remove the oxygen combined with the metal.
  41. Fluxes in Iron and Steelmaking
    Any metallurgical operation in which metal is separated by fusion from the impurities with which it may be chemically combined or physically mixed (as in ores) is called smelting. Since in iron smelting both these conditions with respect to impurities are always present, the production of crude iron involves two processes: (1) the reduction of the metal from its compounds and(2) its separation from the mechanical mixture.Many of the impurities associated with iron ores are of a highly refractory nature; that is, they are difficult to melt. The purpose of the flux then is to (1) render such substances more easily fusible and (2) to furnish a substance with which these impurities may combine in preference to the metal. The chief natural flux is limestone (CaCO3).
  42. the sluggishness of the atoms and molecules in rearranging to the state with the greatest long range order is related to the macroscopic property known as
    viscosity. honey is more viscous than oil and then in turn more viscous than water
  43. complex molecules or impurities are included and either a high viscosity or a rapid cooling rate are conditions for __ instead of crystal formation
    glass
  44. a ceramic is a partially __, partially ___ combination of metallic and non-metallic elements. The covalent forces tend to establish chains and networks in space, and the ionic forces provide structural alternatives, which make it easy to incorporate other ions and to decrease the long range-order, thus making the formation of a glass more probable.
    ionic, covalent
  45. Glass usually fails in tension rather than ___ for the reason that a little accidental crack locally magnifies the tensile stress and since glass does not work harden, tension causes brittle fracture
    compression

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