MEEN 350: Final

T/F ___Ceramics may be crystalline, partially crystalline, or amorphous ___Ceramics have large tensile strengths but low compressive strengths. ___A glass experiences a sudden change in density when cooling from the melt ___In ceramics, a large porosity results in large strength.

T F F F

T/F Related to hot working and cold working in metals ___Surface finishes tend to be poorer after hot working than cold working ___Both cold working and hot working generally strengthen metals ___Hot working only occurs at temperatures above room temperature ___Mechanical properties tend to be anisotropic after both cold and hot working

T F F T

T/F ___Ti alloys are highly resistant to fatigue damage ___Mg alloys are highly ductile ___Precious metals typically have poor corrosion resistance ___Nb and W have high melting points (>1925°C), and are thus refractory metals. ___Al alloys usually suffer from a ductile to brittle transition at low temperatues ___Cu alloys usually exhibit both high electrical and thermal conductivity

T F F T F T

T/F related to homogeneous and heterogeneous nucleation ___Homogeneous nucleation requires more undercooling than heterogeneous nucleation ___Homogeneous nucleation usually occurs in a well-inoculated liquid ___Heterogeneous nucleation requires less free energy for nucleation than homogeneous nucleation ___Homogeneous nucleation commonly occurs on the surfaces of casts

T F T F

T/F ___At the eutectic composition, an alloy can solidify at a constant temperature ___For effective dispersion strengthening, the dispersed phase should be needle-like as opposed to round ___Intermetallic compounds are usually hard and brittle ___For effective dispersion strengthening the dispersed phase should be continuous ___Stoichiometric intermetallic compounds exist over a range of compositions ___Faster solidifications results in smaller interlamellar spacing

T F T F F T

T/F The fracture toughness (Kc) of a steel sample could be increased by ___Heating the sample ___Increasing the sample thickness ___Decreasing the rate of loading

T F (decrease the thickness) T

T/F The following materials typically exhibit strength described by a weibull distribution: ___Ceramics ___Glasses ___Metals ___Thermoplastic polymers above Tg

T T F F

MC Which of the following is NOT a main reason for adding alloying elements to the steels? a) Improved thermal conductivity b) Solid solution strengthening c) Precipitation strengthening d) Improved corrosion resistance e) improved hardenability

a

MC If you wish to buy a plain low carbon steel, which of the following AISI steels should you pick? a) 4340 b) 1010 c) 1080 d) 52100

b

304 stainless steel is often used in medical applications due to its high ductility and non-magnetic nature. Based on these characteristics, what category of stainless steel (SS) does it belong to? a) Ferritic SS b) Martensitic SS c) Austenitic SS d) Precipitation Hardened SS

c

MC Crystalline ceramics are typically brittle and hard because a) they typically have small dislocation densities b) they typically have large dislocation densities c) their atomic structures result in a large resistance to dislocation motion d) their bonds are typically weak e) their free electrons are mobile

c

MC Engine blocks made of cast iron need to provide large thermal conductivity, high damping capabilities, and large wear resistance. Which of the following cast irons best provides these characteristics? a) White iron b) Malleable iron c) Gray iron d) Pure Iron e) Nodular Iron

c

MC A hypereutectoid steel often contains hard and brittle cementite along the grain boundaries of pearlite. Which of the following heat treatments will be mitigate this issue by changing the microstructure? a) Annealing b) Nomalizing c) Austenitzing d) Spheroidizing e) Process-annealing

d

MC A refractory material is one that a) readily forms a glass b) is readily cast c) has excellent toughness at high temperature d) maintains its strength at high temperature e) All of the above

d

T/F ___Thermoset plastics are generally more ductile than thermoplastics ___A larger degree of polymerization generally results in polymers with larger strengths and toughness ___The glass transition temperature refers to when a polymer melts ___Crystallization of a polymer results in an increase in its density ___Thermoset plastics are easily recycled

F T F T F

T/F ___Martensitic transformations only occur in the Fe-C system ___Certain materials can age harden at room temperature. ___Pure metals can be age hardened ___Tempering of martensitic steel increases its ductility ___Over-aging can occur when the aging temperature is large enough such that incoherent precipitates form.

F T F T T

T/F Higher temperatures (but below the melting point) tend to make steels more ductile and less strong, likely due to ___Increased Dislocation Density ___Increased Mobility of Dislocations ___Exceeding the ductile-brittle transition temp (DBTT) ___Exceeding the glass transition temperature (Tg)

F T T F

T/F ___Hardenability refers to the ease with which a steel can be quenched to form pearlite. ___The dividing point between steels and cast irons is 1%C ___In the AISI system for designating steels, the first two numbers refer to the major alloying elements of steel. ___Quenching hardens most steels while tempering increases the toughness. ___Spheroidizing improves the machinability of hypereutectoid steels.

F (ability to form martensite) F (2.11%C) T T T

MC Which of the following are considered ceramics? a) Diamond b) Silica c) Alumina d) Ice e) All of the above

e