Chapter 6 - Diffusion

Chapter 6 - Diffusion - Chapter 6: Diffusion ISSUES TO...

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1 Chapter 6: Diffusion ISSUES TO ADDRESS. .. How does diffusion occur? Why is it an important part of processing? How can the rate of diffusion be predicted for some simple cases? How does diffusion depend on structure and temperature?
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Diffusion Diffusion - Mass transport by atomic motion Mechanisms Solids – vacancy diffusion or interstitial diffusion 2
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3 Diffusion Interdiffusion : In an alloy, atoms tend to migrate from regions of high conc. to regions of low conc. Initially Adapted from Figs. 6.1 and 6.2, Callister & Rethwisch 3e. After some time
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6 Diffusion Self-diffusion : In an elemental solid, atoms also migrate. Label some atoms A B C D After some time A B C D
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Diffusion Mechanisms 7 Vacancy Diffusion : atoms exchange with vacancies applies to substitutional impurities atoms rate depends on: -- number of vacancies -- activation energy to exchange. increasing elapsed time
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8 Diffusion Simulation • Simulation of interdiffusion across an interface: Rate of substitutional diffusion depends on: -- vacancy concentration -- frequency of jumping. (Courtesy P.M. Anderson) QuickTime™ and a Cinepak decompressor are needed to see this picture. This slide contains an animation that requires Quicktime and a Cinepak decompressor. Click on the message or image below to activate the animation.
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Diffusion Mechanisms Interstitial diffusion – smaller atoms can diffuse between atoms. 9 More rapid than vacancy diffusion Adapted from Fig. 6.3 (b), Callister & Rethwisch 3e.
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11 Processing Using Diffusion Adapted from chapter-opening photograph, Chapter 6, Callister & Rethwisch 3e. (Courtesy of
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This note was uploaded on 09/05/2011 for the course EMA 3010 taught by Professor Unknown during the Summer '08 term at University of Florida.

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Chapter 6 - Diffusion - Chapter 6: Diffusion ISSUES TO...

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