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diffusion creep

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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
... 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 of flow. The flow of atoms is...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0009218
EISBN: 978-1-62708-176-4
.... The rational polynomial creep equation is best viewed as a simple, flexible means of empirically representing experimental creep data. However, it has also been derived from various formulations of creep behavior. Oding derived the equation from a self-diffusion theory of creep ( Ref 17 , 35 ). The...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005512
EISBN: 978-1-62708-197-9
... the yield stress of the material, and that subsequently, bonding continues by various diffusional processes (including creep). The next qualitative model was proposed by King and Owczarksi ( Ref 4 ), who suggested that bonding takes place in three stages. The first two stages were as described...
Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005606
EISBN: 978-1-62708-174-0
... temperature). (b) First stage: deformation of surface asperities by plastic flow and creep. (c) Second stage: grain-boundary diffusion of atoms to the voids and grain-boundary migration. (d) Third stage: volume diffusion of atoms to the voids During the second stage of joint formation, two changes occur...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001350
EISBN: 978-1-62708-173-3
... few asperities (room temperature). (b) First stage: deformation of surface asperities by plastic flow and creep. (c) Second stage: grain boundary diffusion of atoms to the voids and grain boundary migration. (d) Third stage: volume diffusion of atoms to the voids During the second stage of joint...
Book Chapter

Series: ASM Handbook
Volume: 6A
Publisher: ASM International
Published: 31 October 2011
DOI: 10.31399/asm.hb.v06a.a0005612
EISBN: 978-1-62708-174-0
... surface asperities, thereby reducing interfacial voids. Bond development then continues by diffusion-controlled mechanisms, including grain-boundary diffusion and power-law creep. Fig. 1 Mechanism of diffusion welding. (a) Initial “point” contact and oxide contaminant layer. (b) After some “point...
Series: ASM Handbook
Volume: 6
Publisher: ASM International
Published: 01 January 1993
DOI: 10.31399/asm.hb.v06.a0001446
EISBN: 978-1-62708-173-3
... deformation of surface asperities, thereby reducing interfacial voids. Bond development then continues by diffusion-controlled mechanisms, including grain-boundary diffusion and power-law creep. Fig. 1 Mechanism of diffusion welding. (a) Initial “point” contact and oxide contaminant layer. (b) After...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005536
EISBN: 978-1-62708-197-9
... consider the diffusional reactions in the multicomponent system during the carbon enrichment step and the diffusion step of the gas carburizing process, and to determine how the composition and the amount of each phase vary with time and distance from the gas/solid interface and the carbon profile of the...
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
... 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. Because diffusion is extremely sensitive to temperature, at lower temperatures lattice diffusion...
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
... grain boundary diffusivity. As a consequence, the creep rate varies as d −3 when diffusion occurs via grain boundaries; this mechanism is known as Coble creep. Thus, the grain size exponent can be used to distinguish between mechanisms that exhibit the same stress exponent. Diffusional creep is...
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005411
EISBN: 978-1-62708-196-2
... the creep zone grow with time. The relative kinetics of the two processes must determine the one that dominates. If one assumes that environmental damage dominates and determines the time-dependent crack growth rates, with the rates being controlled by some diffusion-related phenomena, the following...
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006780
EISBN: 978-1-62708-295-2
... sustain significant amounts of crack growth before failure. However, most engineering alloys can lose ductility during high-temperature service, because the diffusion of impurities to the grain boundaries becomes more pronounced. Formation of precipitates can also beneficially influence creep behavior, as...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003545
EISBN: 978-1-62708-180-1
.... Creep damage begins as small holes or cavities that typically form at grain boundaries or second phases. With time and stress, these holes or cavities can link up and form cracks, by both void growth (diffusion controlled) and by shear strain on the grain boundary, that eventually lead to failure of the...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003289
EISBN: 978-1-62708-176-4
... in the number of these atoms as Mo 2 C precipitated. A volume decrease associated with the precipitation process also could account for the observed creep curve trends. Interstitial diffusion of carbon and hydrogen into dislocations has been observed, and alloy strain-aging effects have been found...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003314
EISBN: 978-1-62708-176-4
...-fatigue interaction testing is conducted at a high enough isothermal temperature that thermally activated, diffusion-controlled creep deformation mechanisms can operate under stress as a function of both time and temperature. As a rough rule of thumb, the transition temperature for creep is on the order...
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
... Abstract Plastic deformation can occur in metals from various mechanisms, such as slip, twinning, diffusion creep, grain-boundary sliding, grain rotation, and deformation-induced phase transformations. This article emphasizes on the mechanism of slip and twinning under cold working conditions...
Series: ASM Handbook
Volume: 14B
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v14b.a0005146
EISBN: 978-1-62708-186-3
...) spinning, rubber-pad forming, stretch forming, contour roll forming, creep forming, vacuum forming, drop hammer forming, joggling, and explosive forming. alpha alloys alpha-beta alloys Bauschinger effect cold forming contour roll forming creep forming diffusion bonding drop hammer forming...
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
... stress behavior, concurrent grain growth, and high stress behavior. ambient temperature creep mechanisms diffusion creep diffusional flow dislocation creep Nabarro-Herring creep strain hardening CONSTITUTIVE RELATIONS for metalworking include elements of behavior at ambient temperature as...
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
... 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 mechanisms include: Oxidation...
Series: ASM Handbook
Volume: 4E
Publisher: ASM International
Published: 01 June 2016
DOI: 10.31399/asm.hb.v04e.a0006266
EISBN: 978-1-62708-169-6
... many similarities of cast alloy heat treatment to that of wrought alloys, but end-use requirements require process variations. For example, cast alloys are used for the more demanding creep strength requirements, and cast alloys may have substantially higher heat treatment temperatures or conditions...