# t1f09 - Test 1 MSE 200 ID Number: This is a closed book...

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Test 1 MSE 200 ID Number: This is a closed book test. No notes, books, or information stored in calculator memories may be used. Formulae needed for the examination are provided on the first page. Cheating will be punished severely. All of your work must be written only on these pages and turned in. Your writing must be legible. Be sure that you read and answer all parts of each question. Using a pencil, fill your answers on the scan sheet after you complete the exam and return the scan sheet along with your answers to the examination questions. All questions carry equal points (2.5). Useful formulae X=(Dt) 0.5 , D=Do exp(-Q/kT), Cv= exp(-Gv/kT), k=8.617x10 -5 eV/K hu+kv+lw=0, No=6.03x10 23 , 1 nm = 10 -9 meter Q1. The thickness of tantalum oxide formed upon heating tantalum in oxygen for 1 hour at 850 o C is 200 nm. When tantalum was heated at 700 o C and for the same time, the resulting oxide thickness was 150 nm. 1. The thickness of the oxide formed depends on a. Diffusion coefficient b. time c. both (a) and (b) ( c ) 2. Diffusion coefficient is a. temperature dependent b. time dependent c. constant ( a ) 3. Activation energy Q for diffusion in oxidation of tantalum in terms of k is a. 4110 k b. 411k c. 41100k ( a ) 4. The value of Do in the expression for the diffusion coefficient in cm 2 /sec is a. 4.31x10 -13 b. 43.13x10 -13 c. 0.43x10 -13 ( b ) 5. The value of the diffusion coefficient D in cm 2 /sec at 850 o C is a. 1.11x10 -13 b. 11.11x10 -13 c. 0.11x10 -13 ( a ) Q2. The concentration of vacancies in aluminum at 660 o C is 10 -3 . Lattice parameter of aluminum is 0.406 nm. 1

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6. Concentration of vacancies is a. higher at Lower temperature b. higher at higher temperature c. independent of temperature ( b ) 7. The energy of formation of vacancy in eV is a. 0.0554
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## This note was uploaded on 10/11/2009 for the course MSE 200 taught by Professor Wholedepartment during the Fall '08 term at N.C. State.

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t1f09 - Test 1 MSE 200 ID Number: This is a closed book...

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