exam 1 fall2003 - MAT33 Engineering Materials and Processes...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: MAT33 Engineering Materials and Processes Fell 2003 First Exam September 29'“, 2003, 3.10 — 9.00am NAME Section ProfessorEades Th 12.10pm ...... .. ProfessorEades Th 1.10pm ProfessorRickman P Sloan ...... .. hofessorChan F 9.10m HofessorCaIgill F 10.10nn1 Total............% Please write your final answers in the blanks provided, where nppmpriahe. Closed book. Calculators that store nlphnmnnerios are not allowed. NB. Partial cmdit for questions _will only.r be consideredifymn workings are shown. Useful equations . Useful constants Avogndro‘s nLnnber, NA 5.023 x 10“3 atomshnol Boltzmann's constant, I: 8.62 X [0'5 eWanm-K 1.33 x 10'“ Jim-K Gas constant, R 8‘31 meol-K Metal Structures (25 marks) la.) Sketch the conventional unit cell for the body centered cubic (BCC) sh‘uchoe 13.) Write down the position of the body centering atom within the BCC unit cell in terms of its fractional coordinates. I. n I, I Atomco-ordinates c.) The number of atoms contained per unit cell in the BCC stntcture is (circle one) @4689 d.) The atomic use-ordination ntnnber for this More is (circle one) 4 6 10 32 e.) The close packed direction in this structure is along (tick one) ' the edge of the unit cell thcfacediagonalofthcunitcell .M. the body diagonal of the unit cell 1‘.) Iron has a BCC crystal structure, an atomic radius of0.124nm and an atomic weight of 55.85 gimol. ' Calulateth latti param f CF ‘0 arm as“. aw we... 0-1 : kind“ g . :5 -:n.- 2.2:: (ii) Calculate the volume of the unit cell. 3 V“ a} - (o-zssgtc") : a-acmo‘l'wvé (iii) Calculate the density of ECG Fe. P s "n Aft “"51 ohm! 17¢! “4“. aowl‘- p. less-BS u “256%er z gas/“3 2-3:..“04‘ .s t-on no“ ____ Crystallography (20 mark!) 25L) Determine the Miller indices for the planes shown in the following unit cell. (Circle the correct answer in each case} £131]; A TAFHMPH I 1 .- | Reufrumh I t -1 M (I I1) (111) (T11) (1T1) (TIT) PIE; B at I, laws "1- y: '0 Rec—foul“ a 3 a ham (2 '50) (320) (023) (030) {233) b.) (i) Sketch a simple cubic unit cell and indicate on it the [100] and [110] directions. 1‘ fl. 1 - tun] (ii) What is th‘eanglebetweenthe {100] and the [110] directions in a cubic unit cell? (circle one) 23.3“ 543:” 67.8“ Bonding and Crystalline Imperfections (30 moth 33.) d) b) What bonding type(s) would be expected for the following materials? a. an—s all oi moonlit W .92th c.) liquid chlorine .1. :1.) iron oxide e.) polystyrene M! In“ exalt Which of the above materials has the highest electrical conductivity? Via-5n atqu Which of the above materials has the highest melting temperature? Crystals having an FCC crystal structure ideally have an ABCABC stacking sequence of close packed atomic planes. Identifyr the planar defect type represented by the following stacking sequences: Write down the stacking sequence expected for a metal having the HOP crystal structure ABCABACBA ABCACABC Stackingsequenoe Calculate the fraction of atom sites that are vacant for lead at its melting temperature of 327°C. The energy of vacancy formation in lead is 0.55eVlntom _ a. s _ 0-55 with. a? ( FT 2:? ( . 6 on) 31.1.10 glided: C r 3"“ 1: IO“ ______._... N What is meant by the term amorphous? Can amorphous materials contain dislocations? Briefly explain your answer. . fin mugfkuut Ker m-u‘tl'alifil} “fun-A Aug. rut. hut .. “bum cwtd ohm - in. films M lab fan-3e n'der . Oahuth can mint exist: In a. utifl'nthhe said.TH “martin. mmmdrhm {or M.pxootd «hut-5’“!- Diffusion (25 MM) 4.) You are given the following infcmaiion about the diffusion of nitrogen in BCC iron. Activation energy Q; = 76.7 kamol; II)a = 0.004? x 10“ mzs‘l; atomic radius of N - ;atomic radius ofFe = (112411111: 0» Inn 3.} What is the liker diffusion mechanism for N in 500 Fe? Diffusion mechanism Inhehhé. “$99!!!! h} Calculate the diffusion coefficient, D, forN in BCC Fe at 500°C. D'V-efi-E‘: RT '0 -_e-oou1-~no"" cut?- ‘Ffl'ou ) 5-3! a 143 ‘D . 3-01.! nom'mt s-t c.) Nitrogen gas is to be held in a pressure chamber by a BCC Fe foil only 0.2mm thick. The concentration of nitrogen is 3 x 101‘ eteme on one side ofthe foil but 5 x 101‘ momsfms on the other side. Estimate the flux of nitrogen atoms through the foil at 750°C given that the difiilsicn coefficient at this temperature is 5.67 x 10"]mls". new shd‘ aye-he Mum“ oral use Fuh'l in“ inn). ‘3 1r -D 93$ d1 5 = - I'Gutomm‘f‘ (51!0“~3u|0“) o-oon 3' = 3-: “Dada-«u (“15“ =:==-"—'——""=r ...
View Full Document

This note was uploaded on 02/09/2008 for the course MAT 33 taught by Professor Keith during the Fall '07 term at Lehigh University .

Page1 / 5

exam 1 fall2003 - MAT33 Engineering Materials and Processes...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online