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Nabarro-Herring creep

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Published: 01 January 2006
Fig. 21 Nabarro-Herring creep results from a higher vacancy concentration in regions of a material experiencing a tensile stress vis-à-vis regions subject to a compressive stress. (a) This results in a vacancy flux from the former to the latter areas, and a mass flux in the opposite direction More
Image
Published: 01 January 2005
Fig. 21 Nabarro-Herring creep results from a higher vacancy concentration in regions of a material experiencing a tensile stress vis-à-vis regions subject to a compressive stress. (a) This results in a vacancy flux from the former to the latter areas, and a mass flux in the opposite direction More
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
..., followed by the models of constitutive behavior. It provides a discussion on creep mechanisms involving dislocation and diffusional flow, such as the Nabarro-Herring creep and the Coble creep. The equations for the several creep rates are also presented. Research on the mechanism of the superplastic flow...
Image
Published: 01 December 2009
Fig. 8 Schematic showing the flow of atoms from compressive boundaries to tensile boundaries during diffusional Nabarro-Herring creep. Vacancy flow occurs in the direction opposite to that of the atom flow. More
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
... creep mechanisms that are useful for illustrating the strong stress dependence of dislocation and diffusional flow. ambient temperature Isothermal constitutive modeling physical models strain hardening strain-rate-sensitive flow superplastic flow CONSTITUTIVE RELATIONS for metalworking...
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
... to be controlled by lattice diffusion. The problem of diffusional creep was first addressed by Nabarro and Herring ( Ref 16 ). Creep deformation occurs as a result of coordinated atom movement between different interfaces that results in a macroscopic shape change. Intrinsically, this is an extremely slow...
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
... through the grain interiors provides the most rapid path, then the diffusivity, D , is equal to the lattice or bulk self-diffusion coefficient. This process is known as Nabarro-Herring creep. Alternatively, diffusion may be more rapid through the grain boundaries, in which case D in Eq 4 is replaced...
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
... and accommodation by dislocations. Diffusional Accommodation Models During the later part of 1960s, there were attempts to explain region II in Fig. 1 (the superplastic regime) using diffusional creep models ( Ref 18 , 19 ). Both Nabarro-Herring ( Ref 20 , 21 ) and Coble creep ( Ref 22 ) were also...
Series: ASM Handbook
Volume: 24
Publisher: ASM International
Published: 15 June 2020
DOI: 10.31399/asm.hb.v24.a0006557
EISBN: 978-1-62708-290-7
... such as argon, nitrogen, and helium are often used in the processing environments for metal components. There are four main mechanisms by which pores are eliminated by HIP: plastic flow, power-law creep, Coble (grain-boundary) creep, and Nabarro-Herring (lattice) creep ( Ref 30 ). In sum, all mechanisms...
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002460
EISBN: 978-1-62708-194-8
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005293
EISBN: 978-1-62708-187-0
... 247, René 125) 1185 2165 175 25 4 Mechanisms of Pore Closure during HIP There are four main mechanisms by which pores are eliminated during HIP: Plastic flow Power law creep Coble (grain-boundary) creep Nabarro-Herring (lattice) creep Given appropriate temperature...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003288
EISBN: 978-1-62708-176-4
... ). Fortunately, all these mechanisms can be fitted into two basic categories: diffusional creep and dislocation creep. In diffusional creep, diffusion of single atoms or ions either by bulk transport (Nabarro-Herring creep) or by grain-boundary transport (Coble creep) leads to a Newtonian viscous type...
Series: ASM Handbook
Volume: 24
Publisher: ASM International
Published: 15 June 2020
DOI: 10.31399/asm.hb.v24.a0006552
EISBN: 978-1-62708-290-7
... densifying mechanism until more diffusion-based creep processes take over, such as Nabarro-Herring creep, or bulk creep, and Coble creep, or grain-boundary creep ( Ref 4 , 5 ). With these densification mechanisms and a sufficiently long soak time at HIP conditions, internal defects can be completely erased...
Series: ASM Handbook
Volume: 7
Publisher: ASM International
Published: 30 September 2015
DOI: 10.31399/asm.hb.v07.a0006042
EISBN: 978-1-62708-175-7
...-dependent densification mechanisms take over. Power-law creep becomes the dominant mechanism for a short period of time until Nabarro-Herring creep and Coble creep diffusion mechanisms take over. Professor Michael Ashby and his research group at Cambridge University, United Kingdom, provided an extensive...
Series: ASM Handbook
Volume: 20
Publisher: ASM International
Published: 01 January 1997
DOI: 10.31399/asm.hb.v20.a0002472
EISBN: 978-1-62708-194-8
... and strain components associated with creep processes; stress and temperature dependence; fracture at elevated temperatures; and environmental effects. The article describes the basic presentation and analysis methods for creep rupture. It provides information on the application of these methods to materials...
Series: ASM Handbook
Volume: 21
Publisher: ASM International
Published: 01 January 2001
DOI: 10.31399/asm.hb.v21.a0003448
EISBN: 978-1-62708-195-5
... in nature to Nabarro-Herring creep and is associated with atomic transport in the matrix around the reinforcement phase, incorporating the stress carried by the reinforcement phase, size of the reinforcement, and parameters related to the mass transport in the vicinity of the interface (e.g., boundary...
Series: ASM Handbook
Volume: 13A
Publisher: ASM International
Published: 01 January 2003
DOI: 10.31399/asm.hb.v13a.a0003590
EISBN: 978-1-62708-182-5
..., at which creep mechanisms become operative. The three important creep mechanisms in oxides are grain- boundary sliding, Herring-Nabarro creep, and climb. Grain-boundary sliding allows relative motion along the inherently weak boundaries. Herring-Nabarro creep allows grain elongation by diffusion of ions...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006787
EISBN: 978-1-62708-295-2
... salts or metals can induce other secondary mechanisms, such as galvanic corrosion, crevice corrosion, and pitting corrosion; creep; and fatigue. Impingement by solid particles can contribute to erosion-corrosion, or it can accelerate corrosion in the various gaseous and molten environments. Primary...
Series: ASM Handbook
Volume: 13A
Publisher: ASM International
Published: 01 January 2003
DOI: 10.31399/asm.hb.v13a.a0003671
EISBN: 978-1-62708-182-5
... and physical properties of the material exposed to this environment. A material can degrade at high temperatures on exposure to gaseous, liquid (molten ash, salts, or metal/alloys), or solid-state reaction processes, such as diffusion and interdiffusion, precipitation, and creep. Thermodynamics...
Series: ASM Handbook
Volume: 24
Publisher: ASM International
Published: 15 June 2020
DOI: 10.31399/asm.hb.v24.9781627082907
EISBN: 978-1-62708-290-7