annealing/anneal Heat treatment resulting in the occurrence of equilibrium phases see, e.g., graphitization anneal , solution annealing, in removing of deformation or amorphization ef
Trang 1tion, at various t, there may be different values of the elasticity modulus, its extremities being the Young’s modulus E corresponding to the Hooke’s law at t << τR and what is known as the relaxation modulus ER < E at t
>> τR See also internal friction
anisotropic Having different physical and mechanical properties in various
directions Anisotropy of single crystals is a result of crystalline aniso-tropy, whereas that of a polycrystal is dependent on crystallographic texture (and so on the crystalline anisotropy) as well as on the microstruc-tural anisotropy as, e.g., banded structure or carbide stringers in steels
or an elongated grain structure in heat-resistant alloys ( see Nabarro−
Herring or Coble creep) Anisotropy can be observed not only in
crystal-line solids but also in some liquids (see liquid crystals)
annealing/anneal Heat treatment resulting in the occurrence of equilibrium
phases ( see, e.g., graphitization anneal , solution annealing), in removing
of deformation or amorphization effects or in attaining a required grain size or texture ( see, e.g., recrystallization annealing), or in relieving
chem-ical inhomogeneity and macroscopic residual stresses ( see homogenizing,
stress-relief annealing) In metallic alloys, annealing is a preliminary treatment preparing the microstructure or phase composition to a final
treatment (see, e.g., austenitization and solution treatment) Annealing
after amorphization of single-crystalline semiconductors can restore
sin-gle-crystalline structure
annealing texture Preferred orientation evolved in the course of primary
recrys-tallization or grain growth Recrysrecrys-tallization texture occurs because recrystallization nuclei are of nonrandom orientations and grow into the deformed matrix at different rates It can be similar to deformation texture
or quite different from it Texture changes during grain growth are
con-nected with different driving forces for growth of variously oriented grains and different mobility of their boundaries ( see compromise texture) Grain growth commonly (but not always) results in weakening of the primary recrystallization texture Annealing texture is usually characterized by an
increased scatter and a decreased intensity in comparison to the initial deformation texture, except for a cube texture in some cold-rolled FCC alloys and the Goss texture in ferritic steels.
annealing twin Twin occurring during primary recrystallization or grain growth
Annealing twins are usually observed in materials with low stacking-fault energy, especially on annealing after heavy plastic deformation An annealing twin, depending on its position inside a grain, can have one or two coherent twin boundaries joining up with grain boundaries or inco-herent twin boundaries The twin with two coinco-herent boundaries looks like
a straight band
anomalous x-ray transmission Abnormally low x-ray absorption observed in
thick perfect crystals adjusted at the exact Bragg angle It is also known
as the Borrmann effect
antiferromagnetic Material characterized (below Néel point) by a negative
energy of exchange interaction and equal but oppositely directed magnetic
Trang 2tion, at various t, there may be different values of the elasticity modulus, its extremities being the Young’s modulus E corresponding to the Hooke’s law at t << τR and what is known as the relaxation modulus ER < E at t
>> τR See also internal friction
anisotropic Having different physical and mechanical properties in various
directions Anisotropy of single crystals is a result of crystalline aniso-tropy, whereas that of a polycrystal is dependent on crystallographic texture (and so on the crystalline anisotropy) as well as on the microstruc-tural anisotropy as, e.g., banded structure or carbide stringers in steels
or an elongated grain structure in heat-resistant alloys ( see Nabarro−
Herring or Coble creep) Anisotropy can be observed not only in
crystal-line solids but also in some liquids (see liquid crystals)
annealing/anneal Heat treatment resulting in the occurrence of equilibrium
phases ( see, e.g., graphitization anneal , solution annealing), in removing
of deformation or amorphization effects or in attaining a required grain size or texture ( see, e.g., recrystallization annealing), or in relieving
chem-ical inhomogeneity and macroscopic residual stresses ( see homogenizing,
stress-relief annealing) In metallic alloys, annealing is a preliminary treatment preparing the microstructure or phase composition to a final
treatment (see, e.g., austenitization and solution treatment) Annealing
after amorphization of single-crystalline semiconductors can restore
sin-gle-crystalline structure
annealing texture Preferred orientation evolved in the course of primary
recrys-tallization or grain growth Recrysrecrys-tallization texture occurs because recrystallization nuclei are of nonrandom orientations and grow into the deformed matrix at different rates It can be similar to deformation texture
or quite different from it Texture changes during grain growth are
con-nected with different driving forces for growth of variously oriented grains and different mobility of their boundaries ( see compromise texture) Grain growth commonly (but not always) results in weakening of the primary recrystallization texture Annealing texture is usually characterized by an
increased scatter and a decreased intensity in comparison to the initial deformation texture, except for a cube texture in some cold-rolled FCC alloys and the Goss texture in ferritic steels.
annealing twin Twin occurring during primary recrystallization or grain growth
Annealing twins are usually observed in materials with low stacking-fault energy, especially on annealing after heavy plastic deformation An annealing twin, depending on its position inside a grain, can have one or two coherent twin boundaries joining up with grain boundaries or inco-herent twin boundaries The twin with two coinco-herent boundaries looks like
a straight band
anomalous x-ray transmission Abnormally low x-ray absorption observed in
thick perfect crystals adjusted at the exact Bragg angle It is also known
as the Borrmann effect
antiferromagnetic Material characterized (below Néel point) by a negative
energy of exchange interaction and equal but oppositely directed magnetic
Trang 3β-Al 2 O 3 Impure alumina whose main impurity is Na2O
β eutectoid Ti system Name of a Ti−X alloy system in which the β-stabilizer
X has a limited solubility in β-Ti, and a eutectoid reaction β↔ α + γ takes place (γ is an intermediate phase or a terminal solid solution).
β-Fe Obsolete designation of the paramagnetic α-Fe existing at temperatures
between 768 and 910°C at atmospheric pressure (i.e., between A2 and A3)
Correspondingly, a solid solution in β-Fe was named β-ferrite.
β isomorphous Ti system Name of a Ti–X alloy system in which the alloying
element X is the β-stabilizer and there is no eutectoid reaction in the corresponding phase diagram.
βm phase [in Ti alloys] See metastable β-phase.
β-phase [in Ti alloys] Solid solution of alloying elements in β-Ti
β-stabilizer Alloying element expanding the β-phase field in phase diagrams of
Ti alloys and thereby lowering β/(α+β) transus.
β-Ti High-temperature allotropic form of titanium having BCC crystal structure
and existing above 882°C up to the melting point at atmospheric pressure.
β Ti alloy Alloy with β-stabilizers wherein β-phase is the only phase constituent after air-cooling from temperatures above the β/(α + β) transus Alloys
with a small (∼5 vol%) amount of α-phase are related to the same group
and termed near-β alloys If the β → α transition does not evolve on
air-cooling, these alloys are named metastable β alloys.
background In x-ray structure analysis and texture analysis, an intensity of
scat-tered x-ray radiation between diffraction lines caused mainly by: x-ray flu-orescent radiation emitted by the specimen, diffraction of the white radiation
on the polycrystalline specimen, Compton scattering, and diffuse scattering.
back-reflection Laue method Technique wherein an x-ray source and a flat
film (screen) registering an x-ray diffraction pattern are placed on the same side of the sample
backscattered electron Electron elastically scattered in the direction that is
opposite to the direction of the primary beam The yield of backscattered electrons increases with the atomic number of the substance studied
Backscattered electrons are used in SEM for gaining data on the topog-raphy, microstructure, and chemistry of the specimen surface, as well as
for crystallographic studies (see electron channeling)
Trang 4χ-carbide In high-carbon steels, a transient phase of the composition Fe5C2 with
monoclinic lattice It occurs upon tempering of as-quenched martensite.
CaF 2 structure Crystal structure wherein Ca2+ ions form an FCC sublattice and
F1– ions, occupying half the tetrahedral sites of the first one, form the
second sublattice (see Figure C.1) CaF2 is called fluorite.
calorimetry Technique for studying phase transitions by measuring thermal
effects, i.e., taking off or releasing the heat in the course of the transitions
See, e.g., differential scanning calorimetry
capillary driving force Driving force for migration of grain or phase
bound-aries under the influence of the boundary curvature ( see Gibbs–Thomson
equation); this driving force is directed to the center of the curvature In
a three-dimensional, single-phase structure, it is:
∆g = γgb(ρ1 + ρ2) where γgb is the grain-boundary energy, and ρ1 and ρ2 are the principal
radii of the boundary curvature Capillary driving force promotes normal and abnormal grain growth, as well as shrinkage of porous compacts in the course of sintering.
carbide In binary alloys, an intermediate phase containing carbon In alloys with
more than two components, metallic components can dissolve in binary carbides, forming complex carbides.
FIGURE C.1 Unit cell of CaF2 crystal structure Solid and open spheres show F1– and Ca2+
ions, respectively