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Material Processing
To develop or synthesize the material with a certain structure and properties.
Electromagnetic Force
The attraction force between the nucleus (positive charge) and the electrons (negative charge) around it, keeping the electrons traveling in a continuous and definite orbit.
Strong Force
The force that opposes the electromagnetic force of repulsion between protons. Keeps protons together to form the nucleus.
Weak Force
Forces of interaction between atoms with unstable nuclei. To attain stability, an unstable atomic nucleus loses energy by emitting a radiation (process is known as radioactive decay of atom). In this process, a neutron in the nucleus changes into a proton and an electron. Responsible for the radioactive decay of atom.
Gravity Force
Weakest of the four forces within the atom. Holds the electrons around the nucleus, helping the electromagnetic forces in holding the atom as one part.
Crystal
Composition of atoms, ions, or molecules, which are arranged in a periodic three-dimensional pattern over large atomic distances.
Unit Cell
Basic structural unit or building block of the crystal structure, and it is chosen to represent the symmetry of the crystal structure such that, when it is repeated, the overall crystal structure is formed.
Coordination Number
Property of a crystal structure, which is the number of nearest-neighbor (or touching) atoms of an atom.
Atomic Packing Factor (APF)
Sum of the volumes of all atoms within a unit cell divided by the overall unit cell volume.
Solid Solution
New solid that is formed due to the insertion of impurities inside the structure of the hosting material. The crystal structure of the hosting material is maintained, and no new structures are formed.
Substitutional Solid Solution
In which the solute (impurities) atoms substitute the hosting atoms.
Interstitial Solid Solution
In which the solute (impurity) atoms are inserted between the atomic sites.
Dislocation
A linear or one-dimensional defect around which some of the atoms are misaligned.
Burgers Vector
Represents the magnitude and direction of the lattice distortion resulting from a dislocation in the crystal lattice.
Grain Boundary
Separates two grains or crystals having different crystallographic orientations in polycrystalline materials.
Phase Transformation
A change in the phase of the material upon altering (or changing) temperature or pressure.
Phase Diagram
Graphical representation of the relationships among temperature (and sometimes pressure), composition, and quantities of the phases of an alloy.
Liquidus Line
Line that separates the liquid phase from the solid-liquid mixture in a phase diagram.
Solidus Line
Line that separates the solid phase from the solid-liquid mixture in a phase diagram.
Solvus Line
Line of the solid solubility limit, separating one solid phase from the solid mixture with another solid phase in a phase diagram.
Equilibrium Cooling
Process in which the cooling of an alloy occurs very slowly, wherein phase equilibrium is continuously maintained.
Natural Polymers
Organic materials derived from plants and animals including wood, rubber, cotton, wool, leather, silk, proteins, enzymes, starches, and cellulose.
Synthetic Polymers
Materials that are synthesized from small organic molecules, which include plastics, rubbers, and fiber materials.
Polymer
Compound of high molecular weight (normally organic), the structure of which is composed of chains of small repeat units.
Repeat Unit
Most fundamental structural unit in a polymer chain. A polymer molecule is composed of a large number of repeat units linked together.
Twin Boundary
Special type of grain boundary across which there is a specific mirror lattice symmetry; that is, atoms on one side of the boundary are located in mirror-image positions of the atoms on the other side.
Diffusion
Process of the transfer (or transport) of mass (such as atoms) either within a specific material or from one to another material.
Interdiffusion (Impurity Diffusion)
Process where atoms of one metal diffuse into another.
Self-diffusion
Occurs for pure metals where all atoms of the same type migrate from a region of a high concentration to another region of low concentration of the metal.
Vacancy Diffusion
Atom leaves a normal lattice position to an adjacent vacant lattice site or vacancy.
Interstitial Diffusion
Atom migrates from an interstitial position to a neighboring one that is empty.
Slip
Process by which plastic deformation is produced by dislocation motion.
Slip Plane
Crystallographic plane along which the dislocation line moves.
Slip Direction
Direction of the dislocation line movement.
Hardness
Material ability to withstand the penetration of other materials to its surface. Can also be defined as the material resistance to being scratched.
Anelastic Deformation
Non-permanent, time-dependent deformation, in which the material takes some time to recover the developed strain.
Isotropic Material
Material whose properties are the same in all directions.
Anisotropic Material
Material whose properties along one direction are different from those along the transverse direction.
Solubility Limit
Maximum concentration of solute (impurity) atoms that may dissolve in the solvent (host substance) to form a solid solution at some specific temperature.
Phase
Homogenous portion of a system that has uniform physical and chemical characteristics.
Nonequilibrium Cooling
Process in which the cooling of an alloy occurs at rates higher than the diffusional rates required for the compositional readjustments of the alloy. Results in gradient compositions for one or more of the phases.
Isothermal transformation
Phase transformation process in which the temperature of the alloy is held constant throughout the duration of the transformation.
Coarse Pearlite
Pearlite with thick layers of both the a-ferrite and Fe3C phases. Obtained by isothermal transformation at temperatures just below the eutectoid temperature.
Fine Pearlite
Pearlite with thin layers of both the a-ferrite and Fe3C phases. Obtained by the isothermal transformation in the vicinity of 540 C.
Pearlite Structure
Obtained by cooling (at relatively slow) of y-austenite to a temperature below the eutectoid temperature.
Bainite Structure
Non-lamellar structure consisting of a-ferrite matrix and elongated particles (needles) of cementite (Fe3C).
Spheroidite Structure
Microstructure of steel consisting of a-ferrite matrix and spherical-like particles of cementite (Fe3C).
Fracture
Material failure mode in which the solid part is separated into two or more pieces due to an applied stress that is static (constant or slowly varying with time) and at low temperatures.
Saturated Hydrocarbons
Hydrocarbon molecules in which all bonds are single covalent bonds- that is, each carbon atom is bonded to four other atoms.
Unsaturated Hydrocarbons
Hydrocarbon molecules that have double and triple covalent bonds- that is, each carbon atom is not bonded to the maximum (four) other atoms.
Slip System
Combination of the slip plane and slip direction associated with a dislocation motion.
Elastic Deformation
Non-permanent deformation that is totally recovered upon removing the applied load (stress).
Elasticity
Material behavior, where the material recovers its original shape and dimensions upon removing the applied load (stress).
Plastic Deformation
Permanent deformation after the removal of the applied load (stress).
Plasticity
Material behavior, where the material does not recover its original shape or dimensions upon removing the applied load (stress), exhibiting a permanent deformation.
Engineering Stress
Force divided by the original area that is subjected to the force.
Engineering Strain
Material deformation in reference to its original shape or dimensions.
True Stress
Force divided by the instantaneous area that is subjected to the force.
True Strain
Material deformation in reference to its instantaneous shape or dimensions.
Young's Modulus
Measure of the material elasticity. The slope of the linear stress-strain function within the elastic region.
Proportional Limit
The stress at the end of the proportional (linear) stress-strain line.
Yield Strength
Stress value at the initiation of the plastic zone. At the yield point the material starts to experience plastic deformation.
Tensile Strength
Maximum value of stress that the material can withstand before fracture.
Resilience
Capacity of the material to absorb and store energy when it is deformed elastically.
Modulus of Resilience
Strain energy per unit volume required to stress the material from a zero-stress state up to yielding.
Ductility
Material ability to deform with no fracture.
Ductile Material
Material that experiences large plastic deformation before fracture.
Brittle Material
Material that experiences very little plastic deformation (or no plastic deformation) before fracture.
Fatigue
Form (mode) of material failure that occurs in materials subjected to dynamic and fluctuating stresses (cyclic stresses).
Fatigue/Endurance Limit
Stress below which fatigue failure will not occur.
Fatigue Strength
Stress level at which failure will occur at a specified number of cycles.
Fatigue Life
Number of cycles required to cause fatigue failure of the material when subjected to a specific stress level.
Red Hardness
Material ability to maintain its hardness at elevated temperatures.
Monomer
Stable molecule from which a polymer is synthesized.
Isomerism
Phenomenon by which two or more polymer molecules have the same composition but different structural arrangements and properties.