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  • yield strength describes the transistion from elastic to plastic behaviour
  • unit cell unit of the crystal structure that represents its symmetry
  • yield strength the intersection of the deformation curve and a line parallel to the elastic portion and offset with 0, 2% on the strain axis
  • plastic deformation permanent deformation, plastic region in the non-linear portion of the stress-strain curve, which is when the strain exceeds the elastic limit
  • tensile strength maximum stress in the stress-strain curve
  • ductility measurement of how much plastic strain a material can take, measured by elongation
  • edge dislocation made by cutting, slipping and rejoining bonds across the slip plane
  • screw dislocation upper part of crystal is displaced parallel to the edge of the cut rather than normal to it
  • recrystallization occurs at elevated temp, stress-free grains nucleate at high-stress areas of the microstructure, grains grow together until they constitut the entire microstructure
  • diffusion atomic transformation by atomic motion, needs: an empty site, enough energy to break bonds of neighbour atoms and displace atoms while moving
  • self-diffusion host atoms migrate
  • vacancy-diffusion vacancy exchanges place with host atom or impurity
  • impurity diffusion impurity exchanges place with vacancy
  • interstitial diffusion movement of interstitial impurity atom
  • interdiffusion diffusion in opposite directions
  • steady-state diffusion rate is independent of time, flux proportional to concentration gradient
  • equilibrium phase diagram represents the equilibrium condition of a material as a function of temp and composition
  • solid solution a solid in which one or more elements are dissolved in another so that they are homogenously dispersed at an atomic scale
  • solubility limit composition at which an element no longer will dissolve in another element at given temp
  • solubility solute atoms replace host atoms in the lattice
  • solubility depends on atomic size factor, crystal structure, electronegativity, valences
  • eutec- a normal V meeting a horizontal line
  • peritec- an inverted V meeting a horizontal line
  • -tic a liquid phase is involved
  • -toid all phases are solid
  • delta-ferrite BCC, 1394-1534
  • austenite, gamma-Fe FCC, 910-1394
  • Ferrite, alpha-ferrite BCC, RT-910
  • cementite, Fe3C metastable, very hard and brittle
  • peritectic reaction 1493, delta+L<-->gamma
  • eutectic reaction 1147, L<-->gamma+Fe3C
  • Eutectoid reaction 723, gamma<-->alpha+Fe3C
  • nucleation local-scale diffusion process, rate decreases with decreasing temp
  • martensitic transformation diffusion-less transformation which occurs by a sudden re-orientation of C and Fe atoms from the FCC solid solution to a body-centered tetragonal structure, metastable phase and cannot be found in a phase diagram
  • TTT capture the extent of an isothermal transformation as a function of temp and time, depending on the time-temp history the microstructure will differ
  • pearlite 400-727
  • total energy use of a product the materials, embodied energy, energy of processing, use-energy, maintanance energy, disposal energy
  • flip chip bonding small beads of solder are formed on bonding pads on the die, which is then mounted face-fown on the base and heated up until the solder melts and forms a contact between metal tracks on tje base and the bonding pads
  • electromigration very high current densities, collisions between electrons and atoms in metallic film->drift of atoms in direction of electron flow
  • kirkendall effect 2 species, A and B, are diffusing, B dissolves in A and A dissolves in B, movement of interfaces due to unequal diffusion rates
  • electrical resistivity measure of a materials resistance to current passing through it
  • electrical conductivity is proportional to the number of free electrons, n, and the mobility of electrons which is proportional to the mean free path
  • electrical conductivity is the reverse of resistivity, 1/(resistivity)
  • conductors silver, copper, iron (metals)
  • semi-conductors silicon, germanium, gats
  • insulators glass, concrete, aluminum, polyethylene (ceramics and polymers)
  • electron energy band structure conduction band, valence band
  • conduction band empty, lowest unoccupied energy level
  • valence band filled, highest occupied energy level
  • electronic properties of a solid is a result of the band structure, arrangement of the outermost electron bands and if they are filled with electrons
  • electrical conductivity, high or low larger band gap, lower conductivity at given temp
  • resistivity of metal total resistivity of a metal is the sum of contributions from thermal vibrations, impurities and plastic deformation
  • matthiesen's rule Ptot=Pt+Pi+Pd, Pt=temp effect, Pi=impurity effect, Pd=effect due to deformation
  • superconductivity at critical temp the resistivity drops to zero, the material becomes a superconductor, once set in motion the electrical current will flow forever in a superconducting material
  • intrinsic semiconductor the electrical behaviour is based on the electronic structure inherent to the pure material
  • extrinsic semiconductor the electrical behaviour is due to impurity atoms
  • heat capacity energy needed to heat 1kg of a material by 1K, the ability of a material to absorb heat, energy required to increase the temp of the material
  • thermal expansion thermal strain per degree of temp change
  • thermal conductivity rate of which heat is conducted through a solid at steady-state
  • mean free path distance a phonon travels before scattering
  • thermal shock occurs due to constraint of thermal expansion, occurs due to uneven rapid heating/cooling
  • substitutional solid solution dissolved atoms replace those in host material
  • interstitial solid solution dissolved atoms squeezes into spaces between host atoms
  • carburization carbon atoms diffuse into a material, carbon is an interstitial atom and harden the surface (solution strengthening)
  • epitaxy in epitaxial growth, a layer is mimicking the crystal structure of the layers below
  • doping adding impurities to a semiconductor, makes material an extrinsic semiconductor
  • recovery No major microstructural changes, but dislocations move to lower-energy positions

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