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dislocation boundaries

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Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004020
EISBN: 978-1-62708-185-6
... in fine-grain metals has encompassed many ideas, such as the diffusional creep, dislocation creep with diffusional accommodation at grain boundaries, and concepts of grain-mantle deformation. The article concludes with information on the kinetics of superplastic deformation processes, including low...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005428
EISBN: 978-1-62708-196-2
..., allocating orientations to the grains, and then using the swap method to achieve the desired MDF. Source: Ref 10 Read and Shockley Ref 14 ) derived an analytical expression for the energy (per unit area) of a low-angle grain boundary comprised of a regular array of dislocations. The boundary energy...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005433
EISBN: 978-1-62708-196-2
...-fault energy, dislocation density, grain-boundary character distribution, and so on, but their exact description still remains poorly understood. It is important to recognize that n is just the reciprocal of m . Higher m -values mean greater resistance to external neck formation and hence larger...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005432
EISBN: 978-1-62708-196-2
...°; thermodynamic instability criterion, dislocation density larger than 70% of the maximum occurring value; maximum occurring driving force, 1 MPa; activation energy of the grain-boundary mobility, 1.46 eV; pre-exponential factor of the grain-boundary mobility, M 0 = 8.3 × 10 −3 m 3 N −1 s −1 ; and mesh size...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005455
EISBN: 978-1-62708-196-2
... dislocation glide, twinning, phase transformations, climb of dislocations, grain-boundary sliding, and diffusion of point defects. Which of these deformation processes is activated depends largely on intrinsic properties, for example, the Peierls stress, and extrinsic factors such as temperature and imposed...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006287
EISBN: 978-1-62708-169-6
... particles have a noncoherent interface with the matrix and are too coarse to interfere with the movement of dislocations or grain boundaries. Consequently, they provide no strength increase. Constituent particles are generally not beneficial; in most applications, they are positively detrimental...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004018
EISBN: 978-1-62708-185-6
... important to note that the mechanisms of diffusion creep and grain-boundary sliding may occur during hot working and superplastic deformation processes. Plastic deformation in crystals can occur from the shear motion (slip) of dislocations, which are internal line defects in a crystal...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005438
EISBN: 978-1-62708-196-2
... during software implementation planning to identify suitable programs, software components, and programming languages. It describes the validity tests used in model validation, including boundary-value tests, degenerate problem tests, sensitivity tests, and benchmarking. The article also presents an...
Series: ASM Handbook
Volume: 12
Publisher: ASM International
Published: 01 January 1987
DOI: 10.31399/asm.hb.v12.a0000610
EISBN: 978-1-62708-181-8
... candy fracture, cleavage fracture, brittle fracture, high-cycle fatigue fracture, fatigue striations, hydrogen-embrittlement failure, creep crack propagation, fatigue crack nucleation, intergranular creep fracture, torsional overload fracture, stress-corrosion cracking, and grain-boundary damage of...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005431
EISBN: 978-1-62708-196-2
... Abstract Several methods are developed for the numerical solution of partial differential equations, namely, meshed-solution methods such as the finite-element method (FEM), finite-difference method, and boundary-element method; and numerical algorithms consisting of so-called meshed-solution...
Book Chapter

By Sammy Tin
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005404
EISBN: 978-1-62708-196-2
... constitutive description of the strain-rate-dependent behavior of engineering alloys must take into account the intrinsic causes of damage accumulation in the form of cavitation, dislocation evolution, and grain-boundary sliding. Moreover, because creep occurs at elevated temperatures, seldom does the...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004019
EISBN: 978-1-62708-185-6
... lower energy level. All three processes involve diffusion and thus depend on thermal activation to cause rearrangement of dislocations and grain boundaries. The mechanisms of recovery and recrystallization also depend on the extent of plastic deformation (either during hot working or by cold work prior...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006284
EISBN: 978-1-62708-169-6
...), but a considerable change is the norm for metals of high stacking-fault energy, such as pure copper and iron. In these metals, the dislocations rearrange themselves to form cells, the cores of which contain few dislocations and the boundaries of which are composed of narrow bands of tangled...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005412
EISBN: 978-1-62708-196-2
... boundaries of low energy are composed of periodic arrangements of such units, and grain boundaries with different orientations are a mixture of SUs. Source: Ref 15 Because the two crystals must be strained to permit SUs to be built at their interface, there are dislocations between different kinds of...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005413
EISBN: 978-1-62708-196-2
..., could be envisaged as the incidental dislocation boundaries, identified in TEM studies by Hansen and coworkers ( Ref 22 ), as a dominant microstructural feature in deformed material A local tangle, created at a certain level of the flow stress, is stabilized by various types of attractive junctions of...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0009002
EISBN: 978-1-62708-185-6
... serve as sinks for dislocations. However, the subgrains are more stable. Thus, as more dislocations are absorbed into their boundaries, increasing misorientations are developed, eventually giving rise to an equiaxed structure of high-angle boundaries. Such a mechanism forms the basis for grain...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005403
EISBN: 978-1-62708-196-2
... nucleation events. The large gradients of dislocation density induce considerable grain-boundary migration velocities such that CDRX cannot occur. The new structure then results from repeated cycles of nucleation, growth, and shrinkage of grains. This mechanism is called discontinuous dynamic...
Series: ASM Handbook
Volume: 12
Publisher: ASM International
Published: 01 January 1987
DOI: 10.31399/asm.hb.v12.a0000615
EISBN: 978-1-62708-181-8
... coalescence at no exposure to channel fracture in the highly irradiated condition. At the high exposure level, all dislocation activity was localized in a planar slip band, and cracking eventually initiated and propagated along the resultant dislocation channels, causing fracture toughness to fall off. (J.E...
Series: ASM Handbook
Volume: 10
Publisher: ASM International
Published: 15 December 2019
DOI: 10.31399/asm.hb.v10.a0006644
EISBN: 978-1-62708-213-6
... screw dislocations. (c) Grazing incidence: image from a 4H-SiC wafer showing threading screw dislocations. (d) Reflection: image from a ZnO wafer showing low-angle grain boundaries where μ 0 λ is the linear absorption coefficient, and Φ 0 and Φ H are the angles of...
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003084
EISBN: 978-1-62708-199-3
... qualitatively the stress (shown by the direction of the arrows) at four positions around the dislocation Individual crystal grains, which have different lattice orientations, are separated by large-angle boundaries ( grain boundaries ). In addition, the individual grains are separated by small-angle...