effect of recombination on sink strengths in the rate theory of void swelling

  • 30 Pages
  • 2.67 MB
  • 4231 Downloads
  • English
by
Atomic Energy Research Establishment, [distributed by] H.M.S.O. , Harwell, Oxon, London
Statementby A. D. Brailsford, J. R. Matthews and R. Bullough.
SeriesAERE-R9092
ContributionsMatthews, J R., Bullough, R., Atomic Energy Research Establishment. Theoretical Physics Division.
The Physical Object
Paginationii, 30p.
ID Numbers
Open LibraryOL15114283M
ISBN 10070580299X

Journal of Nuclear Materials 79 () North-Holland Publishing Company THE EFFECT OF RECOMBINATION ON SINK STRENGTHS IN THE RATE THEORY OF VOID-SWELLING A.D.

BRAILSFORD *, J.R. MATTHEWS and R. BULLOUGH UKAEA, Theoretical Physics Division, AERE Harwell, Oxon, 0X11 ORA, UK Received 7 August A perturbation approximation is used to estimate the effect of intrinsic recombination Cited by: The effect of dose rate on the temperature dependence of void swelling of pure metals and commercial alloys is discussed.

Keywords: void swelling, point-defect, recombination, sink strengths, bias factor, theory, nickel, copperCited by: 2.

Bulk point-defect recombination in the rate theory of void-swelling is considered in two ways. TrrcCeO+Ayc) (27) are the results for zero recombination sink strength.

From eqs. (22), (23) or (19) and (20), the limiting value for recombination to have a negligible effect on the sink strengths is that aci/Dyk1 and CtCy/fc2 l (28) (29) If we Cited by: void sink strength using an embedding model valid for low sink densities.

In addition, some limiting analytic with loss of point-defects due to bulk recombination are neglected. the usual quasi-static swelling rate [4] when the effects _-__ --\\ motion on Cited by: 3. The incubation dose may be obtained by graphical methods. This completes the derivation of the swelling formula quoted in the abstract.

Summary The rate-theory approach to void-swelling has been derived from first principles for various types of defect sinks. Rate equations have been formulated and solved to yield the volume swelling by: The rate theory formulation of void growth was utilized to analyze the effects of damage rate on metal swelling.

In par- titular, the swellin behavior of SS was modeled as a function of temperature, over a range of displacement damage rates between lo-’ dpa/s and lOa dpa/s. Bulk recombination in the rate theory of void swelling and irradiation creep is a significant process at low temperatures.

The rate of recombination is proportional to the recombination radius. The sink strength of a void in an environment of similar voids, calculated on the basis of the various physical models discussed in the text; Brailsford and Bullough's model (A), the same model but excluding defect production in the shell of perfect lattice (B), a void embedded directly in the effective medium (C), and a void in a void lattice.

The effect of recombination on sink strengths in the rate theory of void-swelling estimate the effect of intrinsic recombination in the derivation of sink strengths in the rate theory of void.

In a previous paper, a Fully Dynamic Rate Theory (FDR T) was developed 16 for studying the void swelling of metals irradiated with time-varying irradiation sources. This theory was then further utilized in a numerical integration schemer 7 in order to evaluate the void swelling of pulsed fusion reactors.

In the present paper, we present an. Peak swelling region In the preliminary discussion following (16), it was noted that if the void and dislocation sink strengths are always comparable, the effect of self-ion injection on the swelling rate near the peak swelling temperature is negligible.

Reaction Rate Theory$ Concept of Sink Strength 7 Equations for Mobile Defects 7 Void swelling 21 Effect of recombination on swelling Several recent papers have investigated the effect of ignoring bulk recombination in derivations of the sink strengths required for the rate theory of void swelling, irradiation creep, and growth.

A time-dependent rate theory formulation hu been used to study the effects of pulaed irradiation on point defect and void bel~vior at elevated temperatures. It is found that point defects in pulsed tokamakz, O-ptnchs and inertial confine- merit fusion reactors (ICFR) display y-state behavior.

wards sinks lead to other phenomena such as radiation-induced segregation, void swelling, ir-radiation creep and growth.2 All these phe-nomena may have a signi cant (and usually deleterious) impact on the material properties.

The reliable prediction of vacancy and intersti-tial. swelling rates at low dislocation density (Section ), grain boundary and grain-size effects in void swelling, and void lattice formation (Section ).

An essential advantage of the PBM over the FP3DM is the two features of the cascade dam-age: (1) the production of PD clusters, in addition to. Significant evolution of the dislocation and void microstructures that control radiation-induced swelling can occur during this period.

Thus, a theory of incubation must treat time-dependent void nucleation in combination with dislocation evolution, in which the sink strengths of voids and dislocations change in.

The rate theory framework for defect evolution under irradiation. Although the current work focuses only on the nonlinear recombination of vacancy and SIAs, the rate theory framework for instability analysis (Gao et al.

a) is still needed to show how the recombination rate affects the growth rates of perturbation waves, and it is presented in the following. homogenized sink strength terms. The rate of absorption of point defects at microstructural sinks yields an evolution law for the corresponding microstructure features.

For example, the void growth rate (in turn, the swelling rate) is determined by the net difference of vacancy and interstitial absorption at the void surface [8,9]. Fully dynamic rate theory of metal swelling Previous treatments of void growth in neutron irradiated metals at high temperature have used rate theory to calculate the vacancy and interstitial con- centrations, C, and Ci, respectively, based on the work of Brailsford and.

sink strength effect on void swelling rate, titanium-modified austenitic stainless Reaction rate theory of radiation effects, Recoil mixing, Recombination small bubble sink strength effect on void swelling rate. void swelling, In Fe-Ni-Cr alloys, however, the high fluence sink strengths (>5 x 10'0 cm"2) are sufficiently large that the swelling rate" is insensitive to temperature.

Description effect of recombination on sink strengths in the rate theory of void swelling FB2

One consequence of this treatment is that one would expect a similar relative insensitivity of the eventual swelling rate to displacement rate and helium/dpa ratio as observed in Ref. 20 and where S v is the sink strength of voids, which scales with the density and size of voids.

In general when either Q ≫ 1 (that is GBs and dislocations are dominant defect sinks), or Q ≪ 1 (that is voids prevail), the void swelling rate is much lower than that when Q ≈ 1–10 (where sinks are more balanced) R = 4frro(Di + Dv) is the coefficient or recombination, G is the volumtc production rate of point defects and B the bias of dislocations d v d v with respect to voids: B = Z^Zy - ZVZ^ - d _d d v Z± - Zv, where Zv ^ are the sink (dislocation or void) capture efficiencies of point defects and r, N, L, the values describing the void (r, N) and.

Standard rate theory methods have recently been combined with experimental microstructures to successfully reproduce measured swelling behavior in ternary steels around C. Fit parameters have reasonable values except possibly for the recombination radius, R{sub c}, which can be larger than expected.

Numerical simulations of void nucleation and growth reveal the importance additional. T of g theo men unde unco the Void swelling temperature range Net flux of defects into a sink of type “k” is given by the difference in interstitial and vacancy flux: Bias driven growth Annealing term where Y is the total sink strength, Ak is the geometric factor for the sink and Z is the bias factor At low temperatures, the annealing term.

The annihilation rates depend on their diffusions and the sink concentrations and strengths [1, 13]. By using the defect reaction rate theory, a planar system of nonlinear ordinary differential equations (ODEs), named the point defect balance equations (PDBEs), has been proposed by Lomer [ 9 ] for the evolution of the spatially averaged point.

The theory of sink strengths. Phil. Trans. Soc.

Download effect of recombination on sink strengths in the rate theory of void swelling FB2

A87– (). Bullough R., Hayns M. & Wood M. Sink strengths for thin film surfaces and grain boundaries. Nucl. Mater. 90, 44–59 (). Bullough R. & Perrin R. The mechanism and kinetics of void growth during neutron irradiation. ASTM Special Technical Publications Void swelling, Effects of Helium, and Irradiation-Induced Stress Corrosion Cracking etc.) sink strengths, α is the recombination rate coefficient, ηGdpa is the net point defect generation rate, and G i,v em is the total rate of emission • rate theory models can be successfully applied to.

A general theory of the effects of point defect trapping on radiation-induced swelling and creep deformation rates is developed.

Details effect of recombination on sink strengths in the rate theory of void swelling EPUB

The effects on the fraction of defects recombining, and on void nucleation, void growth and creep due to the separate processes of dislocation climb-glide and dislocation climb (the so-called SIPA mechanism) are studied. Void swelling –dose dependence • LOW DOSES ‐ÆLOW AMOUNT PRODUCTION OF POINT DEFECTS ; NOT ENOUGH TO FORM MORE VOIDS & ALLOW THE AMBRYOS TO GROW.

• HIGH DOSES ‐‐ÆLOSSES TERM TO (RECOMBINATION + SINKS) IS OFFSETBY PRODUCTION Transient Swelling Regime Threshold dose Linear Swelling Regime Swelling Fluence (dpa).recombination with an opposite type of defect (i.e., vacancy with interstitial) or by annihilation at fixed lattice sinks, such as dis-locations, voids and grain boundaries.

The effects of spatial vari-ations and defect clustering in cascades are neglected for simplicity. A more detailed account of void swelling including these factors has.The Effect of Matrix Composition on the Swelling Rate-Void Density Correlation It has been found that the correlation which exists between swelling rate and void density is a given matrix composition i.e.

the whole S -Nv curve is changed if the matrix composition is altered, and this is to be expected, since we are then dealing.