a)Using the Gibbs- Helmoltz relations, calculate the values of a h and AS for the reaction b) Calculate the equilibrium Ps2 at 800K over a phase in which the sulfur activity(relative to pure liquid sulfur standard state)equals 10 Question No 28 a) Draw isothermal sections at temperatures above, at and below a ternary eutectic isotherm b)What is the fundamental reason for the phase diagram "rule" that in a binary, isobaric, two-component diagram, the metastable extensions of the line separating one and two phase regions must extend into a one phase field? Question No. 29 a) Using the methods of quantitative metallography how would you determine the solubility of Cu in Ag(simple eutectic)at several temperatures below the eutectic? Describe two methods one using alloys well into the two phase field and one with alloys near the phase boundary b) Determine the grain size of the alloy? give two method Question No 30 Sketch an Ellingham diagram on which you show lines for the formation of the following oxides SiO? AlO3 (from C) ( from CO) H,o (from H, a) Indicate on the graph the location of the oxides that might be reduced with CO/H2 mixtures b) Indicate how you would decide whether or not an oxide might be reduced carbothermicall How do you estimate the critical temperature? c) How can you use electrochemical principles to assist carbothermic reduction( Hall cells)? d) How can you take advantage of the stability of volatile halides to promote carbothermic reduction? Kroll process) Question No 31 How may the yield strength of a pure metal be increased without the addition of alloying elements? Using simple arguments, discuss the mechanism(s) responsible for the increase in strength Question No 32 Sketch a schematic Charpy curve typical of low alloy ferritic steels Show both energy absorbtion and fracture appearance versus test temperature. Sketch the same curves for a precipitation hardened aluminum alloy. How and why do the curves differ?a) Using the Gibbs-Helmoltz relations, calculate the values of Δ H and Δ S for the reaction. 2S(l) = S2(g) b) Calculate the equilibrium PS2 at 800K over a phase in which the sulfur activity (relative to pure liquid sulfur standard state) equals 10-3. Question No. 28 a) Draw isothermal sections at temperatures above, at and below a ternary eutectic isotherm (isobaric system). b) What is the fundamental reason for the phase diagram “rule” that in a binary, isobaric, two-component diagram, the metastable extensions of the line separating one and two phase regions must extend into a one phase field? Question No. 29 a) Using the methods of quantitative metallography how would you determine the solubility of Cu in Ag (simple eutectic) at several temperatures below the eutectic? Describe two methods, one using alloys well into the two phase field, and one with alloys near the phase boundary. b) Determine the grain size of the alloy? Give two methods. Question No. 30 Sketch an Ellingham diagram on which you show lines for the formation of the following oxides. Cu2O FeO SiO2 Cr2O3 Al2O3 CO (from C) CO2 (from CO) H2O (from H2) a) Indicate on the graph the location of the oxides that might be reduced with CO/H2 mixtures. b) Indicate how you would decide whether or not an oxide might be reduced carbothermically. How do you estimate the critical temperature? c) How can you use electrochemical principles to assist carbothermic reduction (Hall cells)? d) How can you take advantage of the stability of volatile halides to promote carbothermic reduction?(Kroll process). Question No. 31 How may the yield strength of a pure metal be increased without the addition of alloying elements? Using simple arguments, discuss the mechanism(s) responsible for the increase in strength. Question No. 32 Sketch a schematic Charpy curve typical of low alloy ferritic steels. Show both energy absorbtion and fracture appearance versus test temperature. Sketch the same curves for a precipitation hardened aluminum alloy. How and why do the curves differ?