Materials Cribsheet - BEST ONE

Materials Cribsheet - BEST ONE - M a t e r ia ls Cr ib Sh e...

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M a t e r i a l s C r i b S h e e t Mike Bebjak Chapter 3 – Crystal Structures Constants & Conversions giga G 10 9 milli m -3 mega M 6 micro µ -6 kilo k 3 nano n -9 centi c -2 pico p -12 k = 1.38× 10 -23 J/ atom K = 8.62× 10 -5 eV/ atom K R = 8.314 J/ mol K N A = 6.023× 10 23 atoms/ mol e = 1.602× 10 -19 C m e = 9.11× 10 -31 kg h = 6.63× 10 -34 J s Atomic Structures Atomic packing factor (APF) = atoms in unit cell unit cell / VV CN = number of atoms that each given atom touches in a unit cell FCC – close packed ABCABC sequence 22 aR = APF = 0.74 CN = 12 4 atoms/ cell BCC – not close packed 4 3 = APF = 0.68 CN = 8 2 atoms/ cell HCP ABABAB sequence = Braggs’ Law: 2s i n nd λ θ = , Density: ii cA nA nA VN ρ == , Planar spacing: 222 2sin na d hkl + + . Miller Indices : Steps – lines: 1. Start at any cell corner; 2. Find coordinates of vectors, subtract; 3. Multiply by common factor, planes: 1. Find intercepts in a, b, c; 2. Find reciprocals 1/ a, 1/ b, 1/ c; 3. Multiply to make integer. Notations – lines: [ u v w] , planes: (h k l), families of planes: { 1 1 1} family includes (1 1 1), (1 1 1) , etc. uu =− Chapter 4 - I m perfections Point Defects - Vacancies: Q V RT V NN e = (N is the total # of atomic sites, Q the energy required to form a vacancy) Thermodynamics: perfect crystal S= 0, add n vacancies to N atoms n S G (G = H - T S). Will create vacancies until G is a minimum. Impurities – Substitutional: replace an atom; Interstitial: lie between atoms; Q sol kT sol Xe = . Linear Defects – Dislocations: edge (extra plane of atoms), screw (shear distortion of lattice) dislocations = S thermodynamically unstable. Planar Defects – Grain boundaries: 1 2 n N = (N – avg. # of grains/ sq. inch, n – grain size # ). Solidification Process : 1. Nucleation; 2. Growth; 3. Impingement grain boundaries form. Metals have more vacancies than self-interstitials. Conditions: 32 0 J/m 0 J/m VS GG ∆< G V RT r Pe = (probability of getting a critical radius r * ), 1/ tp 4 4 3 Ts o l s Gr π πγ ∆= + , * 2 V r G γ = ' 11 1 '' 1 12 2 2 mC A C mm CA CA + + ' 2 1 21 m n CA C nn C AC A ++ ' 1 1 C C CC = + 100 avg ρρ + + + 100 100 avg A AA + + (C-wt% , C’-at% , C’’-conc.) Chapter 5 - Diffusion Types Interdiffusion : atoms of one metal diffuse into another, Self-diffusion : atoms of metal exchange positions Mechanisms Vacancy Diffusion : substitutional atoms diffuse into vacancies (used by interdiffusion & self-diffusion). Interstitial Diffusion : atoms move into interstitials locations (gases, much faster than vacancy). Steady-state Diffusion – diffusion flux doesn’t change with time: 1 M dM J At A dt ⎛⎞ ==⎜ ⎝⎠ , Fick’s 1 st Law: dC JD dx (D – diffusion coefficient), (q – amount diffusing), qJ A = 0 Q RT D De = Chapter 6 – Mechanical Properties of Metals Types of stresses : Tensile, Compressive, Shear, Biaxial Tension Compression, Hydrostatic Stress: 0 F A σ = , Strain: 0 l l ε = , Shear stress: 0 F A τ = , Shear strain: 0 tan l l E = G = , Physics of elasticity: 2 2 FU E r r ∂∂ = ∼∼ , Energy stored: 2 0 0 1 V WV E σε , Poisson’s ratio: x z υ ( ) EG =+ . Work hardening : after they yield, metals get harder to deform Hardness tests : indent
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This note was uploaded on 10/14/2011 for the course ENGINEER CHEM ENG 3 taught by Professor Ghosh during the Spring '11 term at McMaster University.

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Materials Cribsheet - BEST ONE - M a t e r ia ls Cr ib Sh e...

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