Annihilation of positrons in F.C.C. cold-worked polycrystals

Baram, J.; Rosen, M.

doi:10.1002/pssa.2210160128

Cited by 46 publications

(32 citation statements)

References 17 publications

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“…This relation is valid for all f.c.c. metals and was already developed in [5]. Here b denotes the magnitude of the Burgers vector and c0 is a constant.…”

Section: Analysis Of Datamentioning

confidence: 99%

Positron annihilation investigation for an estimation of the dislocation density and vacancy concentration of plastically deformed polycrystalline Ni of different purity

Dlubek

Brümmer

Hensel

1976

Phys. Stat. Sol. (a)

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From the angular correlation measurements of the positron annihilation radiation on cold rolled, polycrystalline Ni of purity 99.99% and 99.84% the curve‐shape parameters S are determined for treating the as‐deformed and annealed samples up to a thickness reduction of 90%. The trapping rate of the positrons can be determined for a thickness reduction up to 15 or 18% for the dislocations and for the vacancies as well. Using known relations for the hardening within range 2 the specific trapping rates are estimated for the dislocations, μd = 2.9 × 10−15 s−1, and for the vacancies, μv = 2.2 × 10−15 s−1. Estimated dislocation densities and vacancy concentrations vary between 108 and 1011 cm/cm3 and 1016 and 1019 cm−3, respectively. Both of them show a remarkable dependence on the purity of the samples. Ni of low purity exhibits formation of vacancy clusters after annealing.

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“…This relation is valid for all f.c.c. metals and was already developed in [5]. Here b denotes the magnitude of the Burgers vector and c0 is a constant.…”

Section: Analysis Of Datamentioning

confidence: 99%

Positron annihilation investigation for an estimation of the dislocation density and vacancy concentration of plastically deformed polycrystalline Ni of different purity

Dlubek

Brümmer

Hensel

1976

Phys. Stat. Sol. (a)

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“…(2). 15,18 The fitted lifetime varies from τ f = 205.4 ± 1.08 ps, for the annealed sample to τ t = 213.3 ± 0.84 ps for the sample having saturated dislocations. The value obtained for ∆τ , which is the increase in positron lifetime in the limit of saturated trapping at dislocations over annihilation in the annealed sample, is 7.9 ± 0.24 ps.…”

Section: Resultsmentioning

confidence: 99%

“…The value obtained for ∆τ , which is the increase in positron lifetime in the limit of saturated trapping at dislocations over annihilation in the annealed sample, is 7.9 ± 0.24 ps. The effective strain (ε) is related to thickness reduction in the following manner 15,16 :…”

Section: Resultsmentioning

confidence: 99%

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Detecting Defects in Aircraft Materials by Nuclear Technique (Pas)

Badawi

2005

Surf. Rev. Lett.

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Positron annihilation spectroscopy (PAS) is one of the nuclear techniques used in material science. The present measurements are used to study the behavior of defect concentration in one of the most important materials aluminum alloys which is the 7075 alloy. It has been shown that positrons can become trapped at imperfect locations in solids and their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values after the saturation of defect concentration. The mean lifetime and trapping rates are studied for samples deformed up to 58.3%. The concentration of defect range vary from 10 15 to 10 18 cm −3 at the thickness reduction from 2.3 to 58.3%. The dislocation density varies from 10 8 to 10 11 cm/cm 3 .

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“…This constant value represents saturation trapping of positrons in defects. The results were interpreted using Baram and Rosen's results, 3 which are as follows. A dislocation is considered to be as a chain of spherical scattering centers of density ρ , given by…”

Section: Methodsmentioning

confidence: 99%

INFLUENCE OF Mg CONTENT ON TRAPPING EFFICIENCY IN Al–Mg SYSTEM BY POSITRON ANNIHILATION SPECTROSCOPY

2006

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PLT and Doppler broadening S-parameter were used for Al-Mg alloy, namely 5005, 5051, 5052 and 5083. The trapping efficiency was estimated for the pervious alloys as 2.42 × 10 9 , 2.29 × 10 9 , 2.24 × 10 9 and 2.27 × 10 9 s −1 cm 3 , respectively and the trapping cross-section was estimated to be as 2.66 × 10 −16 , 2.14 × 10 −16 , 2.10 × 10 −16 and 3.51 × 10 −16 cm 2 , respectively. It is clear that the mean lifetime and S-parameter have the same behavior as a function of deformation degree and saturated at the same value of thickness reduction.

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Annihilation of positrons in F.C.C. cold-worked polycrystals

Cited by 46 publications

References 17 publications

Positron annihilation investigation for an estimation of the dislocation density and vacancy concentration of plastically deformed polycrystalline Ni of different purity

Positron annihilation investigation for an estimation of the dislocation density and vacancy concentration of plastically deformed polycrystalline Ni of different purity

Detecting Defects in Aircraft Materials by Nuclear Technique (Pas)

INFLUENCE OF Mg CONTENT ON TRAPPING EFFICIENCY IN Al–Mg SYSTEM BY POSITRON ANNIHILATION SPECTROSCOPY

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