Thermodynamic analysis of dislocation glide controlled by dispersed local obstacles

Gibbs, G. B.

doi:10.1016/0025-5416(69)90026-3

Cited by 127 publications

(26 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that the evaluation of velocity of dislocations in terms of the characteristic parameters of individual pinning point is difficult. In view of this, average dislocation velocity (ν) in solids containing dispersed obstacles is specified based on average segment length (l s ) and average area (A) swept out by dislocation segments released during thermal activation [29] and this is expressed as where Γ is the forward activation frequency, i.e. the rate of escape of pinned dislocations from obstacle.…”

Section: Framework Of the Proposed Creep Modelmentioning

confidence: 99%

“…the rate of escape of pinned dislocations from obstacle. Based on first-principle using statistical-thermodynamic analysis of dislocations glide controlled by local dispersed obstacles [29][30][31], the forward activation frequency (Γ) is described as where ν D is the Debye frequency and ΔG is the Gibbs free energy during lattice diffusion. The above rate Equation (9) stipulates that the probability of successful thermally activated forward jump for overcoming barrier is given by the multiplication of fundamental frequency with which dislocation segment attempts the energy barrier (νb/2l) and the Boltzmann factor (exp (−ΔG/kT)).…”

Section: Framework Of the Proposed Creep Modelmentioning

confidence: 99%

See 1 more Smart Citation

Constitutive description of primary and steady-state creep deformation behaviour of tempered martensitic 9Cr–1Mo steel

Christopher

Choudhary

2016

Philosophical Magazine

View full text Add to dashboard Cite

The model based on the coupled sine hyperbolic creep rate relation with the evolution of internal stress as a function of strain provides better understanding of primary and secondary creep behaviour of tempered martensitic 9Cr-1Mo steel. The predicted evolution of internal stress as an increase in the internal stress value (or, decrease in effective stress) with strain/time appropriately described the observed decrease in creep rate during primary creep in the steel. The applicability of the model has been demonstrated by comparing experimental and predicted creep strain-time and creep rate-strain/time data of 9Cr-1Mo steel at 793 and 873 K for quenched and tempered and simulated post-weld heat treatment conditions. Irrespective of prior heat treatment and test temperature, the optimised parameters associated with the internal stress values exhibited linear variations with applied stress. The influence of prior heat treatment on primary and secondary creep characteristics of the steel is reflected on the rate constant values associated with the model. At all temperatures and heat treatment conditions, good agreement between the experimental and predicted steady-state creep rates demonstrate the further applicability of the model.

show abstract

Section: Framework Of the Proposed Creep Modelmentioning

confidence: 99%

Section: Framework Of the Proposed Creep Modelmentioning

confidence: 99%

Constitutive description of primary and steady-state creep deformation behaviour of tempered martensitic 9Cr–1Mo steel

Christopher

Choudhary

2016

Philosophical Magazine

View full text Add to dashboard Cite

show abstract

“…Determination of the origin of the temperature and strain-rate dependent flow stress r*, in metallic structures is facilitated by a knowledge of G and A which can be measured experimentally since [2][3][4]:…”

Section: Resultsmentioning

confidence: 99%

Low-temperature deformation behaviour of polycrystalline copper

1971

View full text Add to dashboard Cite

Low-temperature plastic flow in copper was investigated by studying its tensile and creep deformation characteristics. The dependence of the flow stress on temperature and strain rate was used to evaluate the thermal activation energy while the activation area was derived from the change-in-stress creep experiments. A value of 0.6 eV was obtained for the total obstacle energy both in electrolytic and commerical copper. The activation areas in copper of three selected purities fell in the range 1200 to 100 b ~. A forest intersection mechanism seems to control the temperature dependent part of the flow stress. The increase in the athermal component of the flow stress with impurity content in copper is attributed to a change in the dislocation density. The investigation also revealed that thermal activation of some attractive junctions also takes place during low-temperature creep. The model of attractive junction formation on a stress decrement during creep, yields a value of 45 • 10 ergs cm-2 for the stacking fault energy in copper.

show abstract

“…Gibbs developed a rate equation for dislocation movement from first principles using a statistical-thermodynamic analysis of dislocation glide controlled by dispersed local obstacles [11,20] . The creep strain rate, , is determined from the Orowan equation as (6) in which is the density of gliding dislocations with average velocity , and b is Burger's vector magnitude.…”

Section: Physically-based Creep Modelmentioning

confidence: 99%

Mechanistic behaviour and modelling of creep in powder metallurgy FGH96 nickel superalloy

Peng

Tian

Jiang

et al. 2016

Materials Science and Engineering: A

View full text Add to dashboard Cite

Thermodynamic analysis of dislocation glide controlled by dispersed local obstacles

Cited by 127 publications

References 22 publications

Constitutive description of primary and steady-state creep deformation behaviour of tempered martensitic 9Cr–1Mo steel

Constitutive description of primary and steady-state creep deformation behaviour of tempered martensitic 9Cr–1Mo steel

Low-temperature deformation behaviour of polycrystalline copper

Mechanistic behaviour and modelling of creep in powder metallurgy FGH96 nickel superalloy

Contact Info

Product

Resources

About