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Unformatted text preview: .... . m...” “mum, .HN m... '0 Selected Answer: x S. States that ifthe diameters ofthe solute and solvent atoms differ by more than 15%, the solid solubilitywill be limited. Question 5 10 out of 10|)oints ’ The more stable an intermediate phase in an AS alloy system is, the more limited the solid solubilitywill be. 0 Selected Answer: MTrue Question 6 10 out of 10|)oints For an alloywith an intermediate beta solid solution, the solubility in the terminal alpha phase decreases with increasing temperature because the effect ofentropy »- increases with temperature and the composition is higher in beta so the entropy ofmixing is higher in beta. :0 Selected Answer: MTrue Question T 5 out of 20 points The Cu-Zn phase diagram is ofgreat historical and technological importance. Which ofthe following statements are true aboutthe Cu-Zn system? Selected Answers: XA. The large difference in melting points between Cu and Zn results in various eutectic points in the phase diagram. -.® a D. The gamma and delta phase ofbrass are complex cubic phases with large unit cells. a F. The alpha, beta and gamma phases ofbrass are cubic phases. Question 3 0 out of 30 points Undoubtedly, the Fe-C phase diagram is one ofthe most important binary phase diagrams. Please read Chapter 5.1 .2 in Haasen's Physical Metallurgy. Which ofthe following statements are true? Selected x C. Upon annealing the sequence ofphases in pure Fe as a function oftemperature is fcc to bcc to fcc. ,. Answers: a E. At high pressure, the ground state phase ofFe is nonmagnetic hcp. m (3. Carbon occupies octahedral interstitial sites in gamma-Fe (fcc). Md. Ternary additions which expand the gamma field such as Ni, Co and Mn produce austenitic steels, which are non-ferromgnetic, otten easily workable and stainless steels. Question 1 0 out of 10 points Which ofthe followmg statements are true? 0 Selected Answer: x S. The primary enthalpic contribution to the Gibbs free energy in alloys is typically the enthalpy ofmixing (bond formation). Question 2 0 out of 10 points Which ofthe followmg statements about grain boundaries are true? 0 Selected Answer: xD. All ofthe above. Question 3 10 out of 10 points In an electron compounds, phase changes occur 0 Selected Answer' 5A To lowerthe average energy ofelectrons by changing the shape ofthe density ofstates curve Question 4 10 out of 10 points The HumerRotheryml 5% rule" 0 Selected Answer' 5D All ofthe above Question 5 10 out of 10 points ' The more stable an intermediate phase in an AS alloy system is, the more limited the solid solubilityle be. 0 Selected Answer: mTrue Question 6 10 out of 10 points For an alloyWith an intermediate beta solid solution, the solubility in the terminal alpha phase decreases With increasing temperature because the effect ofentropy increases with temperature and the composmon is higher in beta so the entropy ofmixing is higher in beta. Selected Answer. ETrue ‘0 Question 7 5 out of 20 points The Cu-Zn phase diagram is ofgreat historical and technological importance Which ofthe following statements are true aboutthe Cu-Zn system? Selected Answers. x C. The large difference in melting points between Cu and Zn results in various eutectic points in the phase diagram. -® a D The alpha, beta and gamma phases ofbrass are cubic phases. a F. The gamma and delta phase ofbrass are complex cubic phases with large unit cells Question 8 0 out of 30 points Undoubtedly, the Fe-C phase diagram is one ofthe most important binary phase diagrams. Please read Chapter 5.1.2 in Haasen‘s Physical Metallurgy. Which ofthe following statements are true? Selected a E. At high pressure, the ground state phase ofFe is nonmagnetic hcp Answers: a (3 Carbon occupies octahedral interstitial sites in gamma-Fe (fcc). -'0 a H In alpha-Fe (bcc), the strain anisotropy around the C interstitials leads to the Snoek effect of an elastic strain. x l. The addition ofcarbon reduces the stability range ofthe gamma phase in Fe and increases the range of stability ofalpha on the temperature axis. ad Ternary additions which expand the gamma field such as Ni, Co and Mn produce austenitic steels, which are non-ferromgnetic, oflen easily workable and stainless steels Question 7 15 out of 2|] point The Cu-Zn phase diagram is ofgreat historical and technological importance Which ofthe followmg statements are true aboutthe Cu-Zn system? Selected a S Upon cooling. the bcc beta brass phase undergoes an ordering transformation into a S2 phase g Answers: a D. The sequence ofphases in the Cu-Zn system can be understood by the Fermi surface touching the Srilloum zone ofthe various phases at “ ® characteristic electroniatom ratios. a F. The alpha, beta and gamma phases ofbrass are cubic phases. Question 3 I] out of 30 point Undoubtedly, the Fe-C phase diagram is one ofthe most important binary phase diagrams. Please read Chapter fit 2 in Haasen‘s Physical Metallurgy. Which ofthe following statements are true? Selected a E At high pressure, the ground state phase of Fe is nonmagnetic hcp g Answers: a (3 Carbon occupies octahedral interstitial sites in gamma-Fe (fcc). “ a a H In alpha-Fe (bcc), the strain anisotropy around the C interstitials leads to the Snoek effect ofan elastic strain. ad. Ternary additions which expand the gamma field such as NI. Co and Mn produce austenitic steels, which are noneferromgnetic, otten easily workable and stainless steels. Question 6 1|] out of 1|] point For an alloy with an intermediate beta solid solution, the solubility in the terminal alpha phase decreases with increasing temperature because the efi'ect ofentropy {b Increases With temperature and the compoSItion Is higher In beta so the entropy ofmixing IS higher In beta Selected Answer. aTrue =in Question 7 15 out of 20 point The Cu—Zn phase diagram Is ofgreat historical and technological Importance Which ofthe followmg statements are true aboutthe Cu-Zn system? Selected EA The gamma and delta phase ofbrass are complex cubic phases With large unit cells. Answers' a S The sequence ofphases in the Cu—Zn system can be understood bythe Fermi surface touching the Srillouin zone ofthe various phases at 5 characteristic electroniatom ratios. “ ® a C. Upon cooling, the bcc beta brass phase undergoes an ordering transformation Into a S2 phase. x E The ci’a ratio is largerthan the ideal value forthe hcp epsilon phase and smallerthan the ideal yalue forthe hcp eta phase a F The alpha, beta and gamma phases ofbrass are cubic phases. Question 3 I] out of 3|] point Undoubtedly‘ the Fe-C phase diagram is one ofthe most important binary phase diagrams. Please read Chapter 6 1.2 in Haasen's Physical Metallurgy. Which ofthe following statements are true? Selected 5A. Cementite is a metastable phase with an orthorhombic structure. However‘ it requires a very long time during annealing attemperatures between Answers: 550 and no 0 to transform into alpharFe and graphite a S The eutectoid reaction at about U 7 wt 9E. C leads to the formation of pearlite microstructure x D. The equilibrium phase ofiron is antiferromagnetic below 768 C. 5° 5 E. At high pressure. the ground state phase ofFe is nonmagnetic hcp. x F Carbon occupies tetrahedral interstitial sites In alpha-Fe (bcc) a G Carbon occupies octahedral interstitial sites in gamma-Fe (fcc) a H in alpha-Fe (bcc), the strain anisotropy around the C interstitials leads to the Snoek efiect ofan elastic strain flJ. Ternary additions which expand the gamma field such as Ni, Co and Mn produce austenitic steels, which are non-ferromgnetic, oflen easily workable and stainless steels. =I= Cornell Universtt)" Submitted 10127/lllSBAM : Status Completed Score 55 outof‘llEI points Time Elapsed 3 minutes out of5 seconds out on hours < instructions This ooie l5 open book and open notes so please read the lecture notes and corresponding chapters in Ine text book iiyoo do noI knowlhe answerlo a Cluestion Question 1 u out or 1o points Which ofthe following statements are true? 6 Selectedanswer xE AandC Question 2 u out or 1o points Which ofthe following statements about orain boundaries are true? 6 SelectedAnswer XA A grain boundaryhas 3 degrees oftreedom two grain rotation axes and one grain boundary rotation axis Question 3 1o out or 1o points i In an electron compounds, phase changes occur é SelectedAnswer EA To lowerthe average energy ofelectrons bychahgihg the shape ofthe density ofstates curve Question 4 10 out of 10 points The HumeRothery'nEesrule“ d SelectedAnswer ED Allofthe above Question 5 10 out of 10 points The more stable an intermediate phase In ahArEI alloy system Is. the more limited the solid solubility-Will be '6 SelectedAnswer.mTrue ...
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