Section 1D Imperfections

Section 1D Imperfections - Section 1 Crystalline...

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MATE 210 Section 1 Crystalline Imperfections (Smith Chapter 4) Does nature strive for perfection? (i.e., thermodynamically favored) Are materials made of perfect crystals? Are imperfects or defects bad ???
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MATE 210 Crystalline Defects: - lattice disruption, deviation from perfection what are possible imperfections to crystalline structure? - sometimes great efforts needed to achieve pure materials pure, single crystal Si - sometimes desired and designed into a system C strengthens Fe in Steels Cu added to Ag for Sterling Silver - understand effects of defects in order to rid or use them: structure properties
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MATE 210 Point Defects Vacancy vacant lattice site missing atom for normally occupied site always present, equilibrium concentration, N v (depends on T) N = Total number of atomic sites Q v = Energy for vacancy formation k = Boltzman constant = 8.62x10 -5 eV/atom- o K T = Temperature ( o Kelvin) = kT Q N N v v exp How many vacancies / cm 3 at 20 & 1000 o C? Cu Q v = 0.9 eV/atom AW: 63.5 g/mole ρ : 8.4 g / cm 3 Atomic Density (N A ρ / AW)
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MATE 210 Point Defects substitutional
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This note was uploaded on 04/02/2008 for the course MATE 210 taught by Professor Niebuhr during the Spring '05 term at Cal Poly.

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Section 1D Imperfections - Section 1 Crystalline...

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