quiz6spr2000 - We can write E (69- 52) = L (79- 69) E 10 L...

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¥' , , ,); I Quiz 6 ENGSC 3313, Spring 2000 Answer any 4 Questions only. 1 point each In the Cb- V system, state the compositions of a) the first solid fonned and b) the last remaining liquid when a 20 w/o V alloy is cooled slowly from the melt. Cb-V Columbium-Vanadium ,'.n~." Oo."0"."~. ,,"""""- Drawing temperature horizontals at the liquidus and solidus and noting the points of interception, we get a) -8 w/o V b) -35 w/o V 2 In the Cu-Pr system, assign simple chemical formulae to the y, b, e and ~ phases. Cu-Pr Copper-Praseodymium "C 1100 '100' 900 ~, --i I "r-. Extrapolating to the top a/o side, we get y- 14 a/o Pr = CU6 Pr 8 -20 a/o Pr = CU4 Pr e- 33 a/o Pr = CU2 Pr t:; -50 a/o Pr = Cu Pr L , I i.=, y 800 '400' 700 'zoo 60 500 900' ~ 472. ~ 4ool Cu -.79 uu 10 20 30 40 5~a. 60 ,~ Weight Percentage Praseodymi"!m 3. In the Cu-Pr system (question 2), state what phases, in what proportions, the ~ phase decomposes into on heating. At 563°C, l; (69% Pr) ~ E (52% Pr) + L (79% Pr)
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Unformatted text preview: We can write E (69- 52) = L (79- 69) E 10 L 17 We have 100% B at- 71 w/o Sn. To the left, we have 0% B at -2 To the right, we have 0% B at -96 We need to move 1/5 of the way from B in each direction. To the left, the length is -71- 2 = 69 1/5 is- 14, so 71 -14 = .,?1 w/o Sn To the right, the length is -96- 71 = 25 1/5 of25 = 5, hence 71 + 5 = 1.2 w/o Sn 5. To what Mg-Sn alloy composition does this microstructure correspond? An intimate 2 phase mixture, hence a eutectic, hence at the V, hence ill w/o Sn. Glycol etchant (ASTM E407, No. 118) 250 X 3109 "Chinese script'. modificatlon of lamellar eutect~ in a casting. The eutectic consIsts of sharply angular Mg:Sn phase (dark) in Mg maQ1x (light) . You should have heard the name pearlite! What is pearlite? 6. The eutectoid microstructure of a. and Fe3C in steel, into which y iron (austenite) decomposes on cooling. ~...
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quiz6spr2000 - We can write E (69- 52) = L (79- 69) E 10 L...

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