Question

1 picture- problem
2 other pictures- phase diagrams for problem

1. Draw a phase diagram for a binary eutectic alloy with solid solubility, naming and describing the significance of the main features. The binary alloy system of metals A and B contains two intermediate (intermetallic) phases A B and AB2 of narrow composition range, each of which forms by a peritectic reaction A cutectic point also exists, at 85at% B. The melting point of A is higher than that of B. and each metal can take a few per cent of the other into solid solution. (i) Sketch the phase diagram, and label the different phase fields. (ii) Describe the microstructures that you would expect to observe in solid alloys containing . 15at%B 40at% B 60ar%B in each case cooled slowly from the liquid state. 3. Describe the microstructural changes that occur when (i) Ag-10mol% Cu is cooled slowly from 750°C to 500°C, and (ii) Ag-20mol%Cu is cooled slowly from 1000°C to 500°C. In each case, calculate the final equilibrium amounts of the two solid phases. A liquid slag consists of 55mol% MnO and 45mol% Feo. Using the phase diagram provided, describe the solidification process that takes place when the slag is cooled to 1000'C. Calculate the equilibrium compositions, and the relative amounts of the phases present in the slag at 1000°C. 5. Describe suitable compositions and heat treatments to manufacture the following microstructures: (i) 20wt% pearlite dispersed in a matrix of ferrite Gil) Swt% graphite dispersed in a matrix of pearlite.

Answer 1

Solution 3 - Ag-Cu phase diagram Liquid (L) 1000+ ---- - F Temperative °C 8807 750+ - 7007 BAL K780 I G + ß - 50dA/B Cor mol % Cu - (1) Giren composition - Ca = Ag-lomol % Cu - Micgost puctural changes from 750°c to 500°c (a) at temperature range of 750°c to 700°c Co is having = x phase only as seen in the phase diagram between EGG Miro structure will looles like this a phase A grain boundary

(6) to 500°c At temperature range of forc co is having a phere co is having + ß phase as seen in the phace diagnaron treen G and B Migastructure will looles like this a & phone xx- DA L applied grain boundary _c) Final eanlitrium amounts of phases are - For a phase Seansidered x = ABD as DB x 100 % Z tie line and l levey role is - Xa= Co-CB 41007 - coola whore Co=98 mall.ca CB = Cor = 10 mol l.lu CA = 3 mol % Cu Xo = 98 – 10x100 % . 88 -3 = a = 22,63 7 for ß phase Xp = (100-Xd )% = (900 -92.63)). – / XB = 7.37 %)

(1) Gren composition Coz = Ag - 20 mal toca Migostinctional changes from 100% to 5000 At temperature range of 1000°c to 880°c {F to H} Coq is undey Liquid phase only Migostructure will looks like (a) t ( 14 T only liquid phase - without grains (6) At temperature range of 8900 to 78°c {* to I} 1. Coz is having a phase Lignid (2) phase Migostructure will looks like Tot Liquid present ot a phase _C) A+ temperature range of 80°C to 500°c {I to c} Cog is having = x phase 0 + ß phase Migostructure will shift to following A pap phase A d phase grain boundary

(d) Final acvuilibrium amount S of phases are ACO tie line is considered 1. Xa = DC x 100 % ? and lerary rule is applied EX100%. & xx = Co-Cer C Co-GA where Co=Co2=20molto cu :. Xa = 98 - 20 X100% go-3 | 9 x = 82lo •/. | c =(loo-x 27 = x = (100-82.10)%. 5 x's = 17.9 %