Practice Exam II

Practice Exam II - Exam II MSEZOOID - _ ' - Fall 2006 a...

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Unformatted text preview: Exam II MSEZOOID - _ ' - Fall 2006 a Name 550 L U TU) 1L1 '5 Student Number- (3 0 pts) ' 1. Using the attached Cu-Zn phase diagram(there are two versions), please answer ‘ the following questions: a What are the - onents in this hase dia am? List their meltin ( ) points “‘ p . can: e I g I . I Q}, 9.: 4'00 C. (b) HOW many soiid solutions appear in this phase diagram? 7 Name them ‘ . _ (0) Are there any line compounds? Nit? If so, name them ((1) Are there any peritectics in this phase diagram? 5‘ How many? 5 If yes, indicate the melting point 3 and phase name ad: 0" 7067C, Write the equation for one of t em 5 «—"- l 7 1E . (e) 137 there a'eutectic or eutectoid in this phase diagram? M If yes, identify-the ' eutectic (or eutectoid ) temperature (5) and composition(s) _ I n, ' "(11,1 ‘_ a '.gn"._'_liut J " Hg: (R. ' (t) Are ere any other invariant reactions not yet mentioned? [‘96) If yes, what temperature and composition do they occur at? ' (g) Using the Gibbs phase rule, calculate the number of degrees of freedom for points marked A, B and C on the Cu—Zn phase diagram on the next page. Show all your, ' work. ‘ Efi Weigfitfiréfin . 4 w . .., ..fi%%% $3.," . u++ + km NW _ a» $41.1 E E... Ewflgk 4’? i? $35 % £5. "’5 °‘a+L cut‘ 4,993 "XX _9 (54¢ «1,3341% 5 =49 BAH, 42% 7002:, (20 pts) 2. Fer an alloy containing 40 wt% Zn, please answer the following questions; (a) Indicate the phases present, their composition and microstructure at the following temperatures - TEMPERATURE PHASES PRESENT COMPOSITIONS MICROSTRUCTURE I; I . 7<L : LIL O?ov%t/l in : 1000°C T2 = 850‘_’.C ‘ T3 =600°C Oi M (b) Given 200 gm of X0 = 40 wt% Zn, what are the relative amofints of the phases present at 850°C and 600°C??- Show all your work. iSOGC _a_A€, ona‘jm A4: 600% MMWWWWJ - m We! :3 «PK. 'ma 1: -X_L__TXO 0 mo .X-(X . x, W is Kra-Kx " n" “meg : 43-45 _—.. loo .' W m: ' 2’60 '> W a}? - . ~4L-_ ‘ - _- 43 4-5."? . .z \ __ - ' '3. l _ pr “0 W H)“ “‘9 0 (C) Draw the microstructure at 500°C for the following: I - (a) X, z 75% Zn - (b) X0 = 90% Zn (15 pts) 3. Given that D9 = 1.2 x 10—4 mZ/sec and the activation energy for diffusion of Mg in A1 is 131 kJ/mol, calculate the following: (a) What is the diffusion coefficient for Mg in A1 at 500°C? p :_ pg W “(Q/R73 * : D/ssoz):0.2xzat) up ., "—— -D§50 tSSa l/ i H (c) Given that Mg crystallizes in the hop structure and has an average atomic , radius of 0.160nm and A1 has an fee structure and its atomic radius is 0.143nm, - ‘ what kind of solid solution‘do you expect them to make? It) 1 r ' r‘ Salas ‘ n z.“ a. . ...- a. .a' L.‘ Why? 1/147, ‘11 ~57 .454 mimflMilszi - v ‘ r I J I J” m4“ (d oul the answ be same as in (c) if we were considering the addition A1 into a Mg crystal? Why or why not? gas-'1" flew €11. ‘ 11 n 131' an All ' J I ' . t -' I " '- ' 2' ’..‘_:: :- (e) If W add i (diamond cubic - - ith rsg=0.118 nm) into Al, what kind 01b of solid solution might you expect? 11f]: {qflmfi 1Q ‘ f4". 1;. *l’ 7 f .4 ‘1__ ' ' (10 pts) Poly(methyl methacrylate),also known as PMMA or Lucite® or Plexiglass®, is used in place of glass when transparent containers are needed. In fact, the Georgia Aquarium tanks are all made with this material because of its excellent optical . transparency and structural strength. A monomer'of PMMA has the following structure: a (a) Determine what the molecular weight of a monomer of PMMA is? (n10 =16.0, Inc = 12.01, am = 1.008) I (b) If we make a PMMA polymer with a degree of polymerization equal to 2000, I . what is the total polymer molecular weight? . ‘ (2519119) 5. Match the correct pairs. . Fick’s first law a ? used to determine crystal structures Fick’s second law SA temperature above which only liquid exists Substitutional impurity used to image surface of materials 'Frenkel defect - i elongated voids Sehottky defect 5 many mers Edge dislocation 3M liquid of same composition as solid Screw dislocation embedded particles Tilt boundaries integer ratio of components Twin Boundaries absence of an atom Twist Boundaries : 32 mirror image at boundary Inclusions Q used to image thin foils Cracks 6 time dependent diffusion Vacancy ‘ Q ‘ dependent on crystal structure SEM 3 determines type of dislocation TEM V temperature below which only solid exists X—ray diffraction 3T rotation at boundary Slip system _ a line perpendicular to burgers vector .‘Burger’s vector E vacancies in both sublattices Polymers ' Y3. melts into a liquid and different solid Glasses - ‘32 vacancy and interstitial in same sublattice Liquidus ‘ CI line parallel to burgers vector Solidus H can be small or high angle misorientation Congruent C replaces host atom - - Incongruent A steady state diffusion swascewapsngraseeeemeows Intermediate Compound ' E has short range order only .7 BONUS QUESTIONS: _ - a. Determine the expected diffraction angle for the'first-order reflection from the (310) set of planes for BCC chromium when monochromatic radiation of wavelength 0.0711 nm is used. The radius of Cr is 0.125 nm. (( 6 pts) - ' use, new; 2 1%:— 3: kg?) at: weasel-m 0.2386 C! _ 0'0qi26 nav . 0., . _ I __ A :4 kzkkz*avw_ 3‘0 :2 _5:o ‘ I . ' *- ,8 MR: 2.13 ‘SLA‘Q ' W15] .0) (9.07”); zfonaiae) SM» rWheni-s Homecoming? 118% (1 pt) ...
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Practice Exam II - Exam II MSEZOOID - _ ' - Fall 2006 a...

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