Materialteknik

Övningen är skapad 2019-10-29 av fnissenisse. Antal frågor: 67.




Välj frågor (67)

Vanligtvis används alla ord som finns i en övning när du förhör dig eller spelar spel. Här kan du välja om du enbart vill öva på ett urval av orden. Denna inställning påverkar både förhöret, spelen, och utskrifterna.

Alla Inga

  • 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

Alla Inga

Utdelad övning

https://glosor.eu/ovning/materialteknik.7282668.html

Dela