Flashcards
Definitions
Cards in this deck (53)
- 1AlloyA metallic substance that is composed of two or more elements.
- 2AmorphousHaving a noncrystalline structure.
- 3AnnealingHeat treatment where a previously cold-worked metal is softened by allowing it to recrystallise.
- 4Annealing pointThe temperature at which residual stresses in a glass are eliminated within 15 mins.
- 5Atomic packing factorFraction of the volume of a unit cell occupied by hard sphere atoms or ions.
- 6AusteniteFCC iron, gamma-iron.
- 7BCCCommon crystal structure found in some metals. Atoms are located at corners and cell center positions.
- 8Brittle fractureFracture that occurs by rapid crack propagation and without much macroscopic deformation.
- 9Burgers vectorA vector denoting the magnitude and direction of lattice distortion associated with a dislocation.
- 10CalcinationA high temperature reaction whereby one solid material dissociates to form a gas and solid. A one step process in the production of cement.
- 11CementA substance by chemical reaction binds particulate aggregates into a cohesive structure.
- 12Cold workingThe plastic deformation of a metal at a temperature below at which it recrystallises.
- 13Coordination numberNumber of atomic or ionic nearest neighbours.
- 14ConcreteA composite material consisting of aggregate particles bound together in a solid body of cement.
- 15Covalent bondA primary intermolecular atomic bond that is formed by the sharing of electrons between neighbouring atoms.
- 16Crosslinked polymerA polymer in which adjacent linear molecular chains are joined at various positions by covalent bonds.
- 17CrystallineThe state of a solid material characterised by a periodic and repeating three-dimensional array of atoms, ions or molecules.
- 18Ductile fractureA mode of fracture that is attended by plastic deformation.
- 19DuctilityThe measure of a material's ability to undergo appreciable plastic deformation before fracture.
- 20Edge dislocationA linear crystalline defect associated with the lattice distortion at the end of an extra half plane of atoms within a crystal. Burgers vector is perpendicular to the dislocation line.
- 21Elastic deformationDeformation that is non-permanent and is recovered upon release of applied stress.
- 22ElastomerA polymeric material that may experience large and reversible elastic deformations.
- 23FCCA crystal structure found in some of the common elemental metals. Atoms are located at all corners and face-centered positions.
- 24FerriteBCC iron - alpha iron.
- 25ForgingMechanical forming of a metal by heating and hammering.
- 26HCPCrystal structure for some metals. HCP unit call is of hexagonal geometry and is generated by the stacking of close-packed planes of atoms.
- 27HardnessThe measure of a material's resistance to deformation by a surface indentation or abrasion.
- 28Interstitial solid solutionA solid solution wherein relatively small solute atoms occupy interstitial positions between host atoms.
- 29Ionic bondPrimary intermolecular atomic bond existing between two adjacent and oppositely charged ions.
- 30Lattice strainsSlight displacements of atoms relative to their normal lattice positions, imposed by crystalline defects such as dislocations and interstitial and impurity atoms.
- 31Metallic bondPrimary intermolecular atomic bond involving nondirectional sharing of delocalised valence eletrons (sea of electrons) that are mutually shared by all the atoms in the metallic solid.
- 32PearliteA two-phase microstructure resulted from the transformation of austenite of eutectoid compositions and consists of alternating layers of alpha-ferrite and cementite.
- 33Point defectA crystalline defect associated with atomic sites.
- 34Plastic deformationDeformation that is permanent and nonrecoverable after release of applied stress. It is accompanied by permanent atomic displacements.
- 35Precipitation hardeningHardening and strengthening of a metal alloy by extremely small and uniformly dispersed particles that precipitate from a solid solutions.
- 36Repeat unitThe fundamental structural unit for a polymer chain. A polymer molecular is composed of a large number of repeat units that are linked together and successively repeated.
- 37ResilienceThe capacity of a material to absorb energy when it is elastically deformed.
- 38Secondary bondsInteratomic and intermolecular bonds that are relatively weak and has small bonding energies. Dipole interactions are involved. EG; vdw or hydrogen bonding.
- 39Self-interstitialA host atom or ion that is positioned on an interstitial lattice site.
- 40Solid-solution strengtheningHardening and strengthening of metals that result from alloying resulting the formation of a solid solution. Presence of impurity atoms restrict dislocation mobility.
- 41SlipPlastic deformation as the result of dislocation motion. The shear displacement of two adjacent planes of atoms.
- 42Slip systemCombination of a crystallographic plane and the direction within that plane at which slip occurs.
- 43Strain hardeningThe increase in hardness and strength of a ductile metal as it is plastically deformed below its recrystallisation temperature.
- 44Tensile strengthThe maximum stress in tension that can be sustained without fracture.
- 45Thermoplastic elastomerA material that exhibits elastomeric behavior yet is thermoplastic in nature.
- 46ThermoplasticA semicrystalline polymeric material that softens when heated and hardens upon cooling. Whilst in the softened state, shapes may be formed by molding or extrusion.
- 47ThermosetA polymeric material that once having cured (hardened) will not soften again.
- 48Unit cellThe basic structural unit of a crystal structure.
- 49VacancyA site, which is normally occupied, has a missing atom or ion.
- 50Valence electronsElectrons in the outermost occupied electron shell which participates in interatomic bonding.
- 51Van der wall forcesA secondary interatomic bond between adjacent molecular dipoles that may be permanent or induced.
- 52YieldingThe beginning of plastic deformation.
- 53Yield strengthThe stress required to a produce plastic strain, measured using 0.002 offset.
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- Material science Flashcards on Definitions, created by Emily Lo on 19/05/2014.
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- Emily Lo
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