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dislocation structure

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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
... to structural materials, namely, solid-solution strengthening, age/precipitation hardening, dispersion strengthening, grain size reduction, strengthening from cold work, and strengthening from interfaces. It explains the application of predictive models in the atomistic modeling of dislocation structures...
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002355
EISBN: 978-1-62708-193-1
.... Push-pull symmetrical loading ( R = −1) with low stress amplitudes. Number of cycles to fracture, N f = 1.2 × 10 6 cycles Fig. 5 Summary of near-surface dislocation structures as a function of amplitude (expressed here through number of cyles to fracture, N f ) and stacking-fault...
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
..., boron, zirconium, chromium, vanadium, scandium, nickel, tin, and bismuth. The article discusses the secondary phases in aluminum alloys, namely, nonmetallic inclusions, porosity, primary particles, constituent particles, dispersoids, precipitates, grain and dislocation structure, and crystallographic...
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003733
EISBN: 978-1-62708-177-1
..., their dislocations and degrees of ordering (long and short order). It focuses on the common superlattice structures and ordered phases observed in copper-gold and iron-aluminum alloy systems. These superlattice types can be referred to by Strukturbericht symbols and the prototype phase. antiphase boundaries...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004027
EISBN: 978-1-62708-185-6
... the rate of dynamic recovery, leading to a reduction in dislocation density and to the development of “cell” or “subgrain” structures, as shown in Fig. 3 . At strains less than ε m ( Fig. 2a ) these structures may be elongated ( Fig. 3a ) and are variously referred to as “microbands” or “dense...
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
... the rate of sliding is controlled by the rate of accommodation through intragranular slip. The basic model is pictorially shown in Fig. 4 . Ball and Hutchison identified in the concluding section of their seminal paper, “…the grain size is stable and smaller than the dislocation cell structure that would...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005574
EISBN: 978-1-62708-174-0
... the forging required to displace contaminants, the bondline can be characterized as a highly dislocated, high-energy structure. Improvements in weld performance can be made by decomposing this structure and reducing the residual bondline strain energy. Decomposition can occur either by recovery...
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003742
EISBN: 978-1-62708-177-1
... 50 years ( Fig. 1b , Ref 2 ). Three notable trends in microscopy are: (a) the ever-increasing resolution in the images so that smaller and smaller features such as dislocations and atomic arrangements can be identified and associated with larger scale structures; (b) the ability to see through...
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002354
EISBN: 978-1-62708-193-1
... Fig. 13 Three-dimensional image of the saturation dislocation arrangement of monocrystalline copper at γ ap = 2.6 × 10 −5 (region A). Source: Ref 43 Fig. 15 Schematic representation of the dislocation arrangements in (a) a matrix structure and (b) a persistent slip band. Source: Ref...
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
... . This structure parameter is a complex variable that may be comprised of a number of dynamic microstructural variables, such as material composition, grain size, dislocation density, precipitate size, and morphology, that evolve during the course of deformation. Thus, the time-dependent behavior of the structure...
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
... on microstructure and can be varied greatly by thermomechanical processing. There is, however, a lower limit of the yield strength due to the intrinsic lattice resistance to dislocation motion, the so-called Peierls force ( Ref 1 , 2 ). It depends on crystal structure and can be quite high, in particular when...
Series: ASM Handbook
Volume: 14A
Publisher: ASM International
Published: 01 January 2005
DOI: 10.31399/asm.hb.v14a.a0004016
EISBN: 978-1-62708-185-6
... volume. The corresponding “end effect” becomes insignificant when the billet length-to-thickness ratio increases and the number of passes N ≥6. For traditional metalforming processes, the continuous evolution of dislocation structures results in development of cells and subgrain microstructures...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006255
EISBN: 978-1-62708-169-6
.... The dislocated structure helps to improve ductility and workability at lower temperatures by lowering the ductile-to-brittle-transition temperature. The recrystallization temperature of tungsten also decreases as it is worked, so the working temperature must be decreased. Because recrystallization is avoided...
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
..., however, it is recoverable either fully or partly in a time-dependent manner, because there is no dislocation intersections and defect structure development to cause its storage. Thus, stress decreases during and after unloading, releasing ε a . Equation 21 suggests that upon rapid loading...
Series: ASM Handbook
Volume: 14B
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v14b.a0005183
EISBN: 978-1-62708-186-3
... by: (Eq 21) σ = K ′ ε a 0.5 + L ε ˙ a m Microplastic strain is essentially plastic in the sense of its origin; on unloading, however, it is recoverable either fully or partly in a time-dependent manner, because there is no dislocation intersections and defect structure...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003287
EISBN: 978-1-62708-176-4
..., the dislocation structure gradually becomes organized into low-angle boundaries that define subgrains within the grains. This substructure becomes more stable as deformation approaches steady state. Through careful study of deformed materials, it is possible to demonstrate that the size of several key...
Series: ASM Handbook
Volume: 2A
Publisher: ASM International
Published: 30 November 2018
DOI: 10.31399/asm.hb.v02a.a0006487
EISBN: 978-1-62708-207-5
... Fig. 6 Effect of typical warm forming temperatures on strain-hardening exponent of various aluminum alloys. Source: Ref 4 Annealing eliminates strain hardening as well as the microstructural features that develop as a result of cold working. The dislocation structure resulting from...
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
..., the interface energy is lowered at the price of building elastic strain fields. Of course, if the atoms within the SUs are moved out of their positions, the localized strain field is relaxed due to interactions, and the SU model of the structure is invalid. The dislocations separating the low-energy sectors...
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
... DEFORMATION, or the permanent distortion under applied stress, can occur in metals from various mechanisms, such as: Slip from the motion of dislocations (line imperfections) in the crystal structure Twinning, where the crystallographic orientation changes significantly in the region of plastic...
Series: ASM Handbook
Volume: 19
Publisher: ASM International
Published: 01 January 1996
DOI: 10.31399/asm.hb.v19.a0002353
EISBN: 978-1-62708-193-1
... electron microscopy structures of 4140 steel tempered at 400 °C (750 °F) before (a) and after (b) cycling at Δε/2 = 2.5%. There has been a large reduction in dislocation density. Source: Ref 15 Fig. 7 Stress amplitude, Δσ/2, in Fe-0.3C-4Ni-1Al-1Cu steel versus reversals, 2 N , for various...