MSE

T/F Metallic materials have directional primary atomic bonding between atoms
F
T/F In ceramics, the degree of ionic bonding is inversly related to the electronegativity difference between the elements
F
T/F Covalent bonds are directional in nature
T
T/F Weak atomic bonds are characterized by low thermal expansion coefficients
F
T/F The atomic packing factor for BCC structures is higher than for FCC structures
F
T/F The stacking sequence of close packed planes of atoms determines whether a structure is FCC or HCP
T
T/F Elastomers stretch when a stress is applied and recover their original shape when stress is removed
T
T/F Thermosetting polymers can reversibly soften and flow when heated or treated with appropriate solvents
F
T/F Grain boundaries are a type of point defect in crystalline materials
F
T/F Intrinsic semiconductors depend on small amounts of dopants for their semiconducting properties
F
Name the two factors that control how ions are packed in ceramic structures
1-ratio of ion radii
2-charge neutrality
Name the two types of solid solutions
1-interstitial replacement
2-substitutional
with the exception of helium, how manuy electrons are in the outer-most shell of the Noble Gases from column VII of the periodic table
8
what is the name of the outer most shell electrons
valence
The element calcium (Ca) is located in row (period) 4 and column II of the periodic table. Write the electron for the outermost shell of calcium using spdf notation
4s^2
the element oxygen is located in row 2 and column V! of the periodic table. Write the electron for the outermost shell of calcium using spdf notation
2s^2 2p^4
in ionic compounds, does the coordination number increase or decrease as the cation to anion radius ratio increase
increase
Metal or nonmetal? 4 or more valence electrons
nonmetal
Metal or nonmetal? low electronegativity
metal
Metal or nonmetal? forms cations
metal
list four considerations required for extensive substitutional solid solution solubility in metal alloys (Hume Rothery Rules)
1-difference in atomic radii<15%
2-same crystal structure
3-same valence electrons
4-low difference in electronegativity
T/F the electrical conductivity of an intrinsic semiconductor decreases with an increasing temperature
False
T/F adding Boron atoms from column II in the periodic table to Silicon from Column IV produces a p-type extrinsic semiconductor
False
T/F electrical resistance is a materials property
True
T/F increasing the yield strength of a metal by cold working will increase the ductility of the material
False
T/F the ultimate strength of ceramics is the same in compression and as in tension
False: compression>tension
T/F Polymeric materials are brittle at temperatures below the glass transition temperature
True
T/F As the degree of polymerization is increased, the strength of the polymer decreases
False
T/F when a cold worked metal is annealed, new, strain-free grains are nucleated during the grain growth phase of annealing
False
T/F The mechanical properties of a uniaxial fiber reinforced composite are anisotropic
True
if the volume fractions of fiber and matrix are equal, which of these conditions will produce a stronger composite, isostrain or isostress?
isostrain
T/F Austenite is a FCC solid solution of carbon in iron
True
T/F The hardness of martensite is a function of ots carbon content
True
T/F Ferrite (alpha) is a FCC solid solution of carbon in Iron
False
T/F An eutectic reaction is an example of an invariant reaction
True
T/F An eutectoid reaction is an example of a solid-state invariant reaction
True
T/F Interstitial diffusion is slower than vacancy diffusion
False
T/F Fick’s first law of diffusion applies only to steady-state diffusion
True
T/F Diffusivity of one element in another is a function of temperature
True
T/F Solidification of cast iron in a sand mold is initiated by homogeneous nucleation
False
T/F An isomorphous phase diagram results when two elements are completely miscible in each other
True
Three steps during the precipitation hardening of alloys in sequence.
1-Soluutionize
2-Quench
3-Aging
T/F The toughness of BCC metals increases as the temperature decreases
False
An interstitial solid solution of carbon in BCC iron.
austenite b) ferrite c) pearlite d) cementite e) martensite
B
A two phase microstructure which is the result of the eutectoid decomposition of the ?-phase.
austenite b) ferrite c) pearlite d) cementite e) martensite
C
An interstitial solid solution of carbon in FCC iron.
austenite b) ferrite c) pearlite d) cementite e) martensite
A
A metastable phase produced by fast cooling from the ?-phase.
austenite b) ferrite c) pearlite d) cementite e) martensite
E
A stoichiometric compound Fe3C; a hard and brittle phase.
austenite b) ferrite c) pearlite d) cementite e) martensite
D
x

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