a metallic solid or liquid formed from an intimate combination of two or more elements.
a polymer, composed of two different repeating mers, in which the different mer units systematically alternate positions along the molecular chain.
the branch of science concerned with the determination of amorphous solid structures and their systemmatic classification (see also crystallography).
having no long-range order.
exhibiting different values of a property in different crystallographic directions.
a generic term used to denote a heat treatment wherein the microstructrure and, consequently, the properties of a material are altered. Frequently, refers to heat treatment whereby a cold-worked metal is softened by allowing it to recrystallize.
a phenomenon observed in some materials in which complete magnetic moment cancellation occurs as a result of antiparallel coupling of adjacent atoms or ions. The macroscopic solid possesses no net magnetic moment.
a type of polymer chain configuration wherein side groups are randomly poitioned on one side of the polymer backbone or the other.
face-centered cubic iron; also iron and steel alloys that have the FCC structure.
a Fe-C composition consisting of a fine dispersion of cementite in alpha-ferrite. It is an austenitic transformation product that forms at temperatures between those at which pearlite and martensite transformations occur.
Band Gap Energy
for semiconductors and insulators, the energies that lie between the valence and conduction bands.
a monomer unit that has two active bonding positions.
a linear copolymer in which identical mer units are clustered in blocks along the molecular chain.
a material brought about by combining materials differing in composition or form on a macroscale for the purpose of obtaining specific characteristics and properties. The constituents retain their identity such that they can be physically identified and they exhibit an interface between one another.
a composite material consisting of aggregate particles bound together in a solid body by a cement.
the formation of polymers by an intermolecular reaction involving at least two monomer species, usually with the production of a low molecular weight by-product such as water.
the lowest-lying electron energy band that is not completely filled with electrons.
a transformation of one phase to another that does not involve any change in composition.
the number of atomic or ionic nearest neighbors.
a polymer that consists of two or more dissimilar mer units in combination along its molecular chains.
Deteriorative loss of a metal as a result of dissolution environmental reactions.
a primary interatomic bond that is formed by the sharing electrons between neighboring atoms.
the time-dependent permanent deformation that occurs under stress; for most materials it is important only at elevated temperatures.
A polymer in which adjacent linear molecular chains are joined at various positions by covalent bonds.
the state of a solid material characterized by a periodic and repeating three-dimensional arrays of atoms, ions, or molecules.
for polymers, the state wherein a periodic and repeating atomic arrangement is achieved by molecular chain alignment.
a region within a crystalline polymer in which all the molecular chains are ordered and aligned.
a fine-grained crystalline material that was formed as a glass and subsequently devitrified (crystallized).
the phenomenon whereby a force is brought to bear on a moving electron or hole by a magnetic field that is applied perpendicular to the direction of motion. The force direction is perpendicular to both the magnetic field and the particle motion directions.
a measure of the depth to which a specific ferrous alloy may be hardened by the formation of martensite upon quenching from a temperature above the upper critical temperature.
the measure of some materials' resistance to deformation by surface indentation or by abrasion.
Hexagonal Close-Packed (HCP)
a crystal structure found for some metals. The HCP unit cell is of hexagonal geometry and is generated by the stacking of close-packed planes of atoms.
for semi-conductors and insulators, a vacant electron state in the valence band that behaves as a positive charge carrier in an electric field.
a polymer having a chain structure in which all mer units are of the same type.
any metal forming operation that is performed above a metal recrystallization temperature.
a strong secondary interatomic bond which exists between a bound hydrogen atom (its unscreened proton) and the electrons of adjacent atoms.
for an alloy system displaying a eutectoid, an alloy for which the concentration of solute is greater than the eutectoid composition.
for an alloy system displaying a eutectoid, an alloy for which the concentration of solute is less than the eutectoid composition
the irreversible magnetic flux density-versus-magnetic field strength (B-versus-H) behavior found for ferromagnetic and ferrimagnetic materials.
a measure of the energy absorbed during the fracture of a specimen of standard dimensions and geometry when subjected to very rapid (impact) loading. Charpy and Izod impact tests are used to measure this parameter, which is important in assessing the ductile-to-brittle transition behavior of a material.
the initial stage in a phase transformation. It is evidenced by the formation of small particles (nuclei) of the new phase, which are capable of growing.
the void space among closed-packed, hard sphere atoms or ions for which there are six nearest neighbors. An octahedron (double pyramid) is curcumscribed by lines constructed from centers of adjacent spheres.
a relatively weak form of magnetism that results from the independent alignment of atomic dipoles (magnetic) with an applied magnetic field.