Quiz
MECH2300
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Questions in this quiz (70)
1The rate at which diffusion occurs is governed by
- AThe host material
- BThe temperature
- CThe diffusing species
- DAll of the above correct
2Which of the following would be the slowest pathway for diffusion?
- ASubstitutional diffusion correct
- BInterstitial diffusion
- CGrain boundary diffusion
- DDislocation diffusion
3If two different materials are close-coupled together at a raised temperature, diffusion will occur to form a central section which will have a constant composition that is a mixture of the two materials.
- ATrue
- BFalse
4 The possible structures that we can obtain by mixing two metals together in a melt and cooling are
- ATwo separated and pure components
- BSolid solutions
- CA chemical compound
- DA mixture of solid solutions and chemical compounds
- EAll of the above correct
5 Cu has an atomic radius of 128 pm and forms a FCC structure. Fe has an atomic radius of 124 pm and forms a BCC structure (at room temperature). If we mix these two elements, what do we expect to find?
- AA solid solution of Cu and Fe with a BCC structure
- BA solid solution of Cu and Fe with a FCC structure
- CLimited solubility of Cu in Fe and Fe in Cu correct
- DCannot tell from this information
6Interstitials sit between the spaces in a crystal structure and therefore there is no limit to how many can be dissolved into a metal.
- ATrue
- BFalse
7 Creep occurs in all materials under load, assuming that a minimum temperature is reached.
- ATrue
- BFalse
8What is the effect of increasing the temperature on the creep strain?
- AThe instaneous strain increases
- BThe steady-state creep rate increases
- CThe rupture lifetime decreases
- DAll of the above correct
9Creep is dependent on
- ATime
- BTemp
- CStress
- DMaterial
- EAll of the above
10 Which of these processes occur at high temperatures and high stresses?
- ADiffusion Creep
- BDislocation Creep
- CElastic Deformation Only
- DConventional Plastic flow
11To avoid dislocation creep, it is important to
- AChoose a low melting point material.
- BChoose a material with a low yield strength.
- CMake dislocation motion hard in the material by precipitation hardening. correct
- DEnsure that the material is a single solid solution, with no secondary phases.
12To avoid diffusion creep, it is important to
- AEnsuring that the material is a single solid solution, with no secondary phases.
- BChoose a low melting point material.
- CUse a material with a large grain size. correct
- DNone of the above.
13A phase diagram is a thermodynamic map to the equilibrium phases present in an alloy.
- ATrue
- BFalse
14Which of the following, by convention, would not be a solid phase?
- Aalpha
- Bgamma
- CL
- Dbeta
15The solidus line on a phase diagram describes
- AWhere solidification completely occurs.
- BWhere solidification begins.
- CWhere solidification ends.
- DIt depends on the material.
16The eutectic temperature of an alloy is typically
- AHigher than the melting point of the individual metals.
- BLower than the melting point of the individual metals.
- CThe same as the highest melting point.
17. An alloy has a composition that is less than the eutectic composition. This is known as a
- AHypo-eutectic
- BHyper-eutectic
- CIt is still a eutectic
18Consider a Pb-Sn alloy with a composition of 70% Sn, 30% Pb. How much eutectic (weight percent) is formed?
- A23%
- B30.6%
- C61.9%
- D77%
19The primary phase formed from a liquid in a hypo-euctectic alloy often forms as dendrites which are
- ASpherical
- BCubic
- CTree-Like
- DHexagonal
20The choice of a hypo-eutectic alloys allows for higher fluidity in casting, while resulting in a material that combines the ductility of the alpha phase with the hardness of Si.
- ATrue
- BFalse
21Which of these phases is not important in considering steel microstructures?
- AGraphite
- BFerrite
- CCementite
- DAustenite
22Which phase in a steel microstructure can contain the most carbon?
- AFerrite
- BAustenite
- Ciron
23What does a eutectic mean?
- AA solid forming to two solids
- BA liquid forming into 1 solid and 1 liquid phase
- CA liquid forming into two solids
- DNone of the above
24.How does increasing the cooling rate change the pearlite structure?
- APearlite remains the same – it does not change size at all.
- BPearlite is coarser.
- CPearlite is finer
25Quenching means not time for diffusion
- ATrue
- BFalse
26Which is not true about pearlite?
- APearlite forms at the eutectoid temperature.
- BPearlite can be fine or coarse depending on the cooling rate.
- CPearlite has a fixed composition.
- DPearlite is a phase.
27Upon cooling from austenite, a 1% carbon steel first forms
- APearlite at the grain boundaries
- BFerrite at the grain boundaries
- CCementite at the grain boundaries
- DFerrite within the grains
- ECementite within the grains.
28Does tempering martensite strengthen the material?
- ATrue
- BFalse
29he harder you drive a transformation the finer the structure you will get.
- ATrue
- BFalse
30As the carbon content increases the yield and tensile strength will decrease
- ATrue
- BFalse
31Copper is often added to silver for [blank_start]jewelry[blank_end] as it adds extra harness.
- Ajewelry
32 The only phases that can form in an alloy are those that are shown on a phase diagram.
- ATrue
- BFalse
33Which of the following is NOT true of martensite?
- AMartensite is formed by a displacive transformation
- BIt forms when an austenitized steel is rapidly cooled (quenched)
- CIt requires carbon diffusion
- DIt is very hard and brittle
- EIts hardness depends on the carbon content of the steel
34The bainite transformation
- AIs both displacive and diffusional
- BIs temperature and time dependent
- CResults in a structure that has a hardness between pearlite and martensite
- DBoth a and b
- EAll of the above
35A TTT curve allows you to determine which metastable phases form during a particular heat treatment.
- ATrue
- BFalse
36The heat treatment of a steel can significantly change the strength and ductility of the material.
- ATrue
- BFalse
37What is the difference between normalizing and full-annealing?
- ANormalizing is typically done at lower temperatures
- BNormalizing is cooled slower
- CNormalizing is cooled faster
- DNormalizing results in a coarser pearlite structure
- EThey are two names for the same process
38 Tempering of martensite
- AReduces the strain in the material
- BRequires diffusion to occur
- CReduces the brittleness of the material
- DIncreases the ductility of the material
- EAll of the above
39For solid solution strengthening to occur in Aluminium
- ASolute atoms must be smaller than Al atoms
- BSolute atoms must be larger than Al atoms
- CSolute atoms must be the same size as Al atoms
- DSolute atoms must be different in size (either smaller or larger) to Al atoms.
40Which of the following would improve the yield strength of Al alloys?
- AWork hardening
- BSolid solution strengthening
- CPrecipitation hardening
- DAll of the above, in any Al alloy
- EAll of the above, in some Al alloys
41The precipitation hardening process does NOT include:
- AAnnealing
- BSolid solution treatment
- CQuenching
- DAging
42To precipitation harden you need a lot of one phase
- ATrue
- BFalse
43Precipitation hardening increases the yield strength by
- AAllowing dislocations to move more freely
- BObstructing dislocation movement
44Which particles provide the greatest amount of precipitation hardening?
- ALow density small coherent particles
- BHigh density small coherent particles
- CLow density small incoherent particles
- DHigh density small incoherent particles
45Overageing occurs because
- ASpacing of particles allows dislocations to bow around them, rather than cut through them.
- BSpacing of particles allows dislocations to cut through them, rather than bow around them.
- COver time, particles become larger and incoherent
- DBoth a and c
- EBoth b and c
46 The strength in a precipitation hardened structure depends on
- AThe temperature at which ageing took place
- BThe duration of the ageing cycle
- CBoth the temperature and the duration of the ageing cycle
47What effect does the ageing temperature have on the ageing process?
- AIncreased temperature increases the amount of time to peak strength
- BIncreased temperature decreases the amount of time to peak strength
- CPeak strength increases with increasing temperature
- DPeak strength decreases with increasing temperature.
48The use of a precipitation hardened alloy requires consideration of
- AThe service use, as overageing may occur
- BThe construction method, as riveting may induce overageing
- CThe construction method, as welding may induce overageing
- DBoth a and c
- EAll of the above
49Which of the following elements are required for corrosion to occur?
- AA material that can corrode
- BAn environment doing the corrosion
- CAn interface between the material and environment
- DOnly a and b are required
- EAll of a, b and c are required for corrosion to occur
50Corrosion can occur in an environment that doesn’t contain water.
- ATrue
- BFalse
51Oxidation is
- AThe loss of electron(s)
- BThe gain of electron(s)
- CThe loss of solid metal to ions
- DBoth a. and c
- EBoth b. an c.
52The P-B ratio completely governs whether the oxide layer formed on the surface of a metal is protective.
- ATrue
- BFalse
53How can we improve dry corrosion resistance for a metal?
- A) Remove water from the environment
- BApply a protective coating such as paint
- CAdd alloying elements to form a more protective oxide scale
- DBoth a and b
- EBoth b and c
54Electrochemical corrosion requires
- AAn anode
- BA cathode
- CAn electrical connection between anode and cathode
- DAn electrolyte
- EAll of the above
55It is not possible to get electrochemical corrosion if the part is not immersed in a fluid such as water.
- ATrue
- BFalse
56Materials with a higher standard electrode potential in the EMF series tend to
- AAct as the anode
- BAct as the cathode
- CCorrode easily
- DBoth a and c
- EBoth b and c
57 Galvanic corrosion occurs when two dissimilar metals are connected electrically in an electrolyte.
- ATrue
- BFalse
58Aluminium is passive in all environments due to its highly dense oxide film.
- ATrue
- BFalse
59 Pitting corrosion occurs
- AAnytime an oxide or other protective layer breaks down
- BWhen any breakdown in the protective layer is not rapidly repaired
- CRapidly in a localized area
- DBoth a and c
- EBoth b and c
60Ceramics can be
- AIonic
- BCovalent
- CAmorphous
- DCrystalline
- EAll of the above
61The crystal structures for ceramics depends on
- AThe valency of each ion
- BThe number of different ions
- CThe size of each ion
- DAll of the above
62 Which of the following defects is NOT likely to occur in a ceramic?
- ACation interstitial
- BAnion interstitials
- CAnion vacancy
- DCation vacancy
- ESubstitutional impurities
63 Most ceramics are brittle because of the difficulty for slip to occur.
- ATrue
- BFalse
64 What is the effect of porosity on the strength of ceramics?
- AIncreasing amounts of porosity increases the strength
- BDecreasing amounts of porosity increases the strength
- CPorosity has no effect on strength.
65The glass transition temperature is the temperature below which polymer chains cannot flow past each other, and therefore the polymer becomes brittle.
- ATrue
- BFalse
66Polymers can be viscoelastic
- ATrue
- BFalse
67 Introducing cross-links results in a polymer that undergoes little or no viscous behaviour.
- ATrue
- BFalse
68Composites are multiphase materials which have all properties superior to their individual components.
- ATrue
- BFalse
69There is a critical fibre length, above which the applied stress can be mostly transferred to the fibres.
- ATrue
- BFalse
70 Increasing the volume fracture of fibres (past a critical value) leads to dramatic increases in the strength of a composite.
- ATrue
- BFalse
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- Quiz on MECH2300, created by Sophia Ahern on 04/06/2019.
- Author
- Sophia Ahern
- Language
- English
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