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Published: 01 January 2000
Fig. 6 Criterion for viscous glide controlled creep and dislocation climb controlled creep in solid solution strengthened alloys. Source: Ref 9 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 January 2006
Fig. 26 Deformation mechanism maps for (a) zinc-aluminum and (b) lead-tin in terms of grain size versus stress. According to the dislocation mechanisms of superplasticity, a transition from superplasticity to dislocation creep should occur when d /b ≅ 10 μ/τ. This is approximately observed More
Image
Published: 01 January 2005
Fig. 26 Deformation mechanism maps for (a) zinc-aluminum and (b) lead-tin in terms of grain size versus stress. According to the dislocation mechanisms of superplasticity, a transition from superplasticity to dislocation creep should occur when d /b ≅ 10 μ/τ. This is approximately observed More
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
... important cases in which the creep response is quite different. For example, some solid solution strengthened alloys exhibit an inverted primary transient when the interaction between the solute atoms and the gliding dislocations is rate controlling. This observation is illustrated schematically in Fig. 2...
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...
Image
Published: 01 January 2006
Fig. 34 Experimental stress-strain-rate plots for two aluminum alloys ( Table 3 ) having similar matrix chemistry. Calculated results for similar grain sizes are shown for comparison. The top solid line represents dislocation creep. More
Image
Published: 01 January 2005
Fig. 34 Experimental stress-strain-rate plots for two aluminum alloys ( Table 3 ) having similar matrix chemistry. Calculated results for similar grain sizes are shown for comparison. The top solid line represents dislocation creep. More
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...
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
..., or primary creep: Following an instantaneous elastic and plastic strain upon loading, this stage is highly transient because the strain rate decreases rapidly due to the development of dislocation structures within the microstructure. The strain rate decreases until a minimum is reached. II...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003266
EISBN: 978-1-62708-176-4
... are subject to thermally activated processes that can produce continuous plastic deformation (creep) with the application of a constant stress. For metals, various mechanisms are used to explain creep deformation, but all the mechanisms can fall into two basic categories: diffusional creep and dislocation...
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: 14B
Publisher: ASM International
Published: 01 January 2006
DOI: 10.31399/asm.hb.v14b.a0005133
EISBN: 978-1-62708-186-3
... that the creep resistance may be due to an attractive interaction between dislocation segments and dispersed particles. They have also suggested relations for the dependence of the creep rate on the particle size and particle spacing for dispersion-hardened material. According to them, for a fixed volume...
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005506
EISBN: 978-1-62708-197-9
... unchanged throughout the deformation history. Aspects of the material microstructure, such as grain size, dislocation structure, inclusions, vacancies, and so on, have an impact on the deformation rate. Both the time- and strain-hardening approaches are suitable if the creep rate is dominated by a single...
Series: ASM Handbook
Volume: 24A
Publisher: ASM International
Published: 30 June 2023
DOI: 10.31399/asm.hb.v24A.a0006964
EISBN: 978-1-62708-439-0
... m = ~0.4 to 0.55, where T is the testing temperature, and T m is the melting temperature) and high normalized tensile stress (i.e., σ/μ = ~10 −3 to 10 −2 , where σ is the testing stress, and μ is the shear modulus), creep deformation is normally dislocation-dominant. In such conditions...
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
... comparable to an atomic diameter and one dimension that is much greater. An example of a particular line defect, an edge dislocation , is shown in Fig. 11 . The upper half of the crystal shown contains one more atom column than the lower half of it. The resultant atomic disregistry is centered about...
Series: ASM Handbook
Volume: 8
Publisher: ASM International
Published: 01 January 2000
DOI: 10.31399/asm.hb.v08.a0003292
EISBN: 978-1-62708-176-4
..., the above suggestion that the creep behavior of superplastic alloys in region III is controlled by the same type of dislocation process that is dominant in metals at high temperatures is not entirely satisfactory for two primary reasons. First, experimental results in a superplastic copper alloy have...
Image
Published: 01 December 2009
Fig. 3 Plot showing the overall changes in dislocation density, ρ tot , as a function of creep strain for pure iron at 600 °C. Dislocation densities are different within the cell interiors, ρ s , and along the cell walls, ρ. Source: Ref 3 More
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
...-state creep, and the dependence of deformation on both temperature and stress. The simplest and most pervasive idea in creep of metals is an approach to an equilibrium microstructural and mechanical state. Thus a hardening associated with dislocation generation and interaction is countered by a dynamic...
Image
Published: 01 January 1987
Fig. 852 “Departure side pinning” during creep of Inconel alloy MA754. The mechanically alloyed nickel-base superalloy is stabilized by yttria (0.8% Y 2 O 3 ). Samples were tested in creep to 2% strain at 760 °C (1400 °F) and 221 MPa (32 ksi) and then cooled on load. TEM examination revealed More