Journal ArticleDOI
Stress‐Assisted Precipitation on Dislocations
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In this paper, the kinetic theory for the rate of stress-assisted precipitation on dislocations is re-examined in order to extend the work of Cottrell and Bilby.Abstract:
The kinetic theory for the rate of stress‐assisted precipitation on dislocations is re‐examined in order to extend the work of Cottrell and Bilby. Two approximate expressions are used for the elastic interaction between a solute atom and edge and screw dislocations: V=−A sinθ/r and V=−B/r, respectively. The resulting partial differential diffusion equations are integrated numerically to get the time‐dependent rate of precipitation on an isolated dislocation. These results are used to calculate the short‐time part of the precipitation curve for an array of dislocations. Exact steady‐state solutions to the diffusion equations are derived for both interactions and are used with a variational procedure to establish the long‐time part of the curve for a regular array. For very short times the precipitated fraction W is proportional to t⅔ as derived by Cottrell and Bilby, but this result is not accurate over the range of t during which most of the precipitation occurs. The long‐time part of the curve is given a...read more
Citations
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Journal ArticleDOI
Stabilization of metallic supercooled liquid and bulk amorphous alloys
TL;DR: In this article, the authors investigated the stabilization properties of the supercooled liquid for a number of alloys in the Mg-, lanthanide-, Zr-, Ti-, Fe-, Co-, Pd-Cu- and Ni-based systems.
Journal ArticleDOI
Influence of predeformation and agEing of an Al–Zn–Mg alloy—II. Modeling of precipitation kinetics and yield stress
Alexis Deschamps,Yves Bréchet +1 more
TL;DR: In this article, a model for precipitation kinetics integrating nucleation growth and coarsening is presented, which allows the description of competitive kinetics of heterogeneous and homogeneous precipitation.
Journal ArticleDOI
A model of extrusions and intrusions in fatigued metals I. Point-defect production and the growth of extrusions
TL;DR: In this paper, a realistic model of the evolution of the surface profile of persistent slip bands (PSBs) in fatigued metals is proposed based on recent experimental observations, and cracks initiate at the surface steps at the PSB-matrix interface and, at a later stage, also at the notch-peak profile from the random slip processes.
Journal ArticleDOI
Influence of predeformation on ageing in an Al–Zn–Mg alloy—I. Microstructure evolution and mechanical properties
TL;DR: In this article, the ageing kinetics of a ternary Al-Zn-Mg alloy were investigated, and the coupling between prestraining and subsequent ageing was investigated in terms of competition between homogeneous precipitation and heterogeneous precipitation on dislocations.
References
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Journal ArticleDOI
Dislocation Theory of Yielding and Strain Ageing of Iron
A H Cottrell,B A Bilby +1 more
TL;DR: In this article, a theory of yielding and strain ageing of iron, based on the segregation of carbon atoms to form atmospheres round dislocations, is developed and the force needed to release a dislocation from its atmosphere is roughly estimated and found to be reasonable.