ss_9 - F—"_———“——'——i 16 Using the...

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Unformatted text preview: F—"_———“——'——i 16. Using the Ag-Cu phase diagram, determine: a) the melting temperature of pure silver 1)) the melting temperature of pure copper c) the eutectic temperature and eutectic composition d) the maximum solid solubility of Cu in (Ag) e) the maximum solid solubility of Ag in (Cu) ® CiboSOC @ \O%ADC (9 "TR: "Wm ca: Ema Jig) of; Z%-\ USED/a Cu 5 $0kul‘aiLfi‘l 03- (U no Jig Cu talk-K sank ‘aULUQ—"ALLTV 5. god “Q. ch- t~\,”\4{I""/('_, by? Ail-Elam h-PER ctNT 'coEEE'F ' "fie 5 10 15 20 25 30 35 40 45 50 60 70 30 90 200 so 90 100 30 40 50 60 7’0 Sq m 20 ATOMIC PER CENT COPPER Cu Fig. 11. Ag—Cu F— _..___l 17. For a composition of Ag~30 at% Cu, for T1 = 900 °C, T2 = 800 °C, T3 = 779 0C, T4 ‘—“ 778 0C, and T5 = 200 °C: a) identify the phase or phases present 13) detemme the composition of each phase c) determine the fraction of each phase (1) sketch a possible microstructure Ctooz - <6z>o°c 69 L L» 0L (9 C : 30417va C“: \1‘ 0195C“ L (1": gwma (U - . 75°43 z 0.‘6\ C9 Q'QA {if '94-?» 0.\"\ \.DO/ _% _' wax—30 , oL eta—m fi_ 18. For a composition of Cu-IO at%Ag, repeat 17a-17d for T1=1050 “C, T2=800 °C, and T32778 0C. \o 50°C 4300 °C 1367 Z: L. O( ‘ "CR: \0 We in CK: \0 (to [1—fi______ I 23. Suppose you are flying to dissolve difi‘erent elements into solid copper. Develop an argument based on the Hume«Rothery rules to estimate whether you would expect Low, Moderate, or High solid solubility of each of the following three elements in Copper (Cu): silver (Ag); silicon (Si); carbon ( C). Co K95 3“ C’ (KNEW k emu: FCC Tr CC ‘3‘“ bgtb Z 03% oft flaws/fit _ fi—__‘____————l 24. Use the Hume-Rother rules to assess the solid solubility of copper in silver. Compare your prediction with the Ag-Cu phase diagram. Co W M Fit, WW. Ram-m vam m gnaw \. ‘1‘ NM WV ‘50“ “NT: \IMWS; as: «M. m Wm. meos \s \2’,<;% \mwa. W WT as: (U. M». %\\.\\\922..\Txt$ sum? 'W L) N35 $mud: \NNVgL \\ WM $°\UE>\UT<‘I Wu DM. \b—kw‘ “1wa W "M- tw, bmm> cm kxssuxkfi \UU am, to, M mm “mm. & MST thKXEF‘L “Daub fioLoFDmm xeaav 3&— n NWQBCCQJBNW W fi__________‘ 26. (a) Derive an expression describing the critical nucleus size, (1*, for a cubed-shaped nucleus, forming by a homogeneous process, with edge length d in an undercooled liquid metal. (b) Would you expect (1* to increase or decrease as the undercooling is increased? Briefly justify your answer. (9) Would you expect that the undercooling required for nucleation would increase or decrease if some nucleation catalysts were added to the liquid as it cools below its melting temperature? l—i_—____—_ I 30. Refer to the C-rich portion of the Fe-C phase diagram (a) Briefly explain why the maximum solid solubility of C is higher in FCC Fe than in BCC Fe. (b) What is the maximum solubity of C in austenite at T=1000°C? Suppose several samples of an Fe—0.8wt%C alloy are annealed until equilibrath at T=1000°C. - One sample is quenched rapidly from 1000°C to room temperature. - A second sample is cooled slowly to 800°C, held for a short time, then quenched to room temp. — A third sample is cooled to 700°C, held for 5 minutes, then quenched to room temperature. - A fourth sample is cooled to 700°C, held for 8 hours, then cooled slowly to room temperature. (c) for each of these four samples: (i) sketch the microstructure you would expect each to have at room temperature (be careful to label the various features in the sketches); (ii) Make three different rankings(highest to lowest) for the four samples after they cool to room temperature. First rank them in terms of their yield strengths. Then rank them in terms of their hardness. Finally rank them in terms of their ductility. Briefly justify your answers. (9 escalates. W \Qwevms swabs in w; m. LAQZJTK W WS'L “.3 Volt . fir—ifi_ — ——_l 31. Consider a 1.1 WI% C Fe-C alloy annealed at 1000°C. (a) Suppose this alloy is cooled slowly to 724°C and held there. What phases are present? What are their compositions? How much of each phase is present? (b) Suppose the alloy is cooled quickly from 10000C to 724°C and held there. Would you expect there to be any significant difference in the resulting microstructure compared to that produced by the cooling treatment in part (a)? (c) Suppose the alloy is cooled quickly by quenching in oil fiom 1000°C to room temperature. What phases are present? What are their compositions? How much of each phase is present? (d) Suppose the alloy is cooled slowly from 100000 to 724°C, held at 724°C for 1 hour, and then quenched in oil to room temperature. What phases are present? What are their compositions? How much of each phase is present? 961- \.\ g (9.93% ® K-t‘flaC boot:- 6‘6.}_Dmaz Cd; 0.02J'4C k _..._ ,7 A #W “M..———.._..._.__m_.~___ !k r r : v x 1 n .w L“ —| _ _ m ....H l A I — - ‘ ‘ af‘icm i 5 ‘ l f i ‘ 1 1 E j, : :600 — w - — A I»— ——;~ ~ ; - -~ ---i— 7 «£7 ~ 771;- ——‘ Aw — 29:0 1533 C mags-C i J i r . J i ; = ‘ _ Smut)in 01 i _, 1500 H .. J ...‘ E Liqmo .. graphne in . w, 2,30 “VFW I | ‘ i A Eiqwo‘ Iran 140:, 1394 C . . _ '____ L...“ .1 .._L E m... .. 7‘“ if” fi_. i .. 2550 I v ‘ : I‘ ‘ .1 i 1. A, .m___ ._.._._..._ ,:_. . w—-nl_ —.._— mm“ 1—— ‘Luw r 7 W, V. mu... 7. m .. —.. 300 I | ' ; 5 5' i g g 1227 c ; ' i 1 g 42.6% I: 1 _i,.——«~w-[ 1200 _ V . i , (yfiFe) ;,___._._ ._.Jk._mfi°J_.___f‘...L“54 ac WM. mm}. ‘ “ 2190 b] Austenite : 2‘9“! - "-‘H—F' 5“‘ ““'—" — ‘- uoo I . : 11481”C “ . = ' ' . 20m ‘ V , I ’ . I l i J - 1 I . U ' Cementite '- fo. 1000 ._ Austenite 1830 .5. 912 ° g 909 A V 1650 ' C E. /n '9 ' 3D 7.0 Carbon, w1% Fig. 1 indicate iron-graphite diagram. Source: Ref 1 Temperature. °F Iron-carbon equilibrium diagram up to 6.67 w:% C. Solid lines indicate Fe-FeJC diagram: dashed lines ...
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This note was uploaded on 10/03/2009 for the course E E344 taught by Professor Libera during the Spring '09 term at Stevens.

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ss_9 - F—"_———“——'——i 16 Using the...

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