POSITRON ANNIHILATION AND XRD FOR DETECTING Al ALLOYS (50XX)

2004 ◽  
Vol 11 (02) ◽  
pp. 167-171 ◽  
Author(s):  
EMAD BADAWI
Keyword(s):  
Positron Annihilation ◽  
Al Alloys ◽  
Preferred Orientation ◽  
Doppler Broadening ◽  
Degree Of Deformation ◽  
Mean Lifetime ◽  
Mg Content

The positron annihilation parameter (mean lifetime) increases with increasing Mg contents for annealed and quenched samples (50 XX ). Positron parameter τ, s (Doppler broadening) increase with increasing Q.T for the same (50 XX ). The preferred orientation is one of the most important parameters that can be observed by XRD for materials, for such measurements in our observation: the dependence of the preferred orientation on the Mg content, the dependence of the preferred orientation on the Q.T, and the dependence of the preferred orientation on the degree of deformation.

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

2006 ◽  
Vol 13 (04) ◽  
pp. 485-488
Author(s):  
EMAD BADAWI ◽  
M. A. ABDEL-RAHMAN ◽  
M. O. ABDELHAMED
Keyword(s):  
Positron Annihilation ◽  
Cross Section ◽  
Positron Annihilation Spectroscopy ◽  
Trapping Efficiency ◽  
Doppler Broadening ◽  
Deformation Degree ◽  
S Parameter ◽  
Mean Lifetime ◽  
The Mean ◽  
Mg Content

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 × 109, 2.29 × 109, 2.24 × 109 and 2.27 × 109 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.

The 3d Electrons and Microdefects in Binary Ti-Al Alloys Studied by Positron Annihilation

2011 ◽  
Vol 399-401 ◽  
pp. 99-102
Author(s):  
Wen Deng ◽  
Xiao Lei Guo ◽  
Bing Xie ◽  
Ding Kang Xiong ◽  
Yu Yang Huang
Keyword(s):  
Grain Boundary ◽  
Positron Annihilation ◽  
Free Electron ◽  
Positron Lifetime ◽  
Al Alloys ◽  
Doppler Broadening ◽  
Al Content ◽  
Open Volume ◽  
Ti Content ◽  
Coincidence Doppler Broadening

The behavior of 3d electrons and microdefects in binary Ti-Al alloys with Al contents from 47at.% to 53at.% have been studied by coincidence Doppler broadening and positron lifetime techniques. It has been found that the 3d electron signals in the spectra of binary Ti-Al alloys increase with Ti content. In Al-rich Ti-Al alloys, on increasing Al content, the open volume of defect on grain boundary increases while the density of free electron decreases. On the contrary, in Ti-rich Ti-Al alloys, on increasing Ti content, the open volume of defect on grain boundary decreases, and the electron density of the grain boundary increases.

Effect of Mg Contents on Trapping Efficiency in Al-Mg System Using PAS

2007 ◽  
Vol 265 ◽  
pp. 7-11
Author(s):  
N.A. Kamel
Keyword(s):  
Cross Sections ◽  
Mg Alloys ◽  
Trapping Efficiency ◽  
Thickness Reduction ◽  
Doppler Broadening ◽  
Degree Of Deformation ◽  
S Parameter ◽  
Mean Lifetime ◽  
The Mean ◽  
Al Mg Alloys

PLT and the Doppler broadening S-parameter were used to characterize the Al-Mg alloys, AA5005, AA5051, AA5052 and AA5083. The trapping efficiencies of these alloys were estimated to be 2.42 x 109, 2.29 x 109, 2.24 x 109 and 2.27 x 109 s-1 cm3, respectively, and the corresponding trapping cross-sections were estimated to be 2.66 x 10-16, 2.14 x 10-16, 2.10 x 10-16 and 3.51 x 10-16 cm2. It was found to be very clear that the mean lifetime and S-parameter exhibited the same behaviour as a function of the degree of deformation, and that they saturated at the same degree of thickness reduction.

Effect of Nature Aging on Positron Lifetime Spectroscopy in Casting and Wrought Al-alloys

2007 ◽  
Vol 265 ◽  
pp. 13-18 ◽  
Author(s):  
M.A. Abdel-Rahman ◽  
M. Abdel-Rahman ◽  
N.A. Kamel ◽  
M.S. Abdallah ◽  
Emad A. Badawi
Keyword(s):  
Aluminum Alloys ◽  
Positron Annihilation ◽  
Point Defects ◽  
Positron Lifetime ◽  
Natural Aging ◽  
Al Alloys ◽  
Isochronal Annealing ◽  
Mean Lifetime ◽  
Positron Lifetime Spectroscopy

Positron annihilation has been performed in order to study the isochronal annealing of wrought (2024, 7075) and cast (AlSi11.35Mg0.23, AlSi10.9Mg0.17Sr0.06) aluminum alloys, at temperatures ranging from RT to 773K, after having been deformed at RT to 25% deformation. Two annealing stages of the microstructures were distinguished, which were attributed to recovery in (2024, AlSi11.35Mg0.23, AlSi10.9Mg0.17Sr0.06) due to point defects and dislocations, respectively, and only one (due to dislocations) in (7075). Also, natural aging for up to more than 650 days was studied as a function of mean lifetime.

GRAIN SIZE IN CASTING AND WROUGHT Al-ALLOYS BY POSITRON LIFETIME TECHNIQUE

2005 ◽  
Vol 12 (02) ◽  
pp. 197-202
Author(s):  
M. A. ABDEL-RAHMAN ◽  
R. M. ABDEL-LATIF ◽  
M. S. ABDALLAH ◽  
EMAD A. BADAWI
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Positron Lifetime ◽  
Fortran Program ◽  
Al Alloys ◽  
Degree Of Deformation ◽  
Mean Lifetime ◽  
The Mean

Positron behavior at grain boundaries is characterized by their bulk diffusibility D, their bulk free lifetime τf and their trapped lifetime τt(τt > τf). AlSi 11.35 Mg 0.23, AlSi 10.9 Mg 0.17 Sr 0.06, 7075 and 2024 alloys have been homogenized at 673 K for 12 hours. The mean lifetime, as (indirectly) measured at various strains (degrees of deformation), show a good fitting with a FORTRAN program. τf and τt for the above materials are shown as: (187.3 ± 0.10, 229.7 ± 0.10), (198.0 ± 0.10, 230.3 ± 0.10), (205.4 ± 0.05, 213.4 ± 0.06) and (197.1 ± 0.55, 215.2 ± 0.57) Ps respectively. The mean lifetime was found to vary exponentially with the degree of deformation.

Annihilation Lifetime Spectroscopy Using Positrons from Bremsstrahlung Production

2012 ◽  
Vol 331 ◽  
pp. 41-52 ◽  
Author(s):  
Andreas Wagner ◽  
Wolfgang Anwand ◽  
Maik Butterling ◽  
Thomas E. Cowan ◽  
Fine Fiedler ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Linear Accelerator ◽  
Electron Accelerator ◽  
Positron Annihilation Spectroscopy ◽  
Doppler Broadening ◽  
Electron Linear Accelerator ◽  
Positron Annihilation Lifetime ◽  
Electron Bremsstrahlung ◽  
New Type ◽  
Set Up

A new type of a positron annihilation lifetime spectroscopy (PALS) system has been set up at the superconducting electron accelerator ELBE [ at Helmholtz-Zentrum Dresden-Rossendorf. In contrast to existing source-based PALS systems, the approach described here makes use of an intense photon beam from electron bremsstrahlung which converts through pair production into positrons inside the sample under study. The article focusses on the production of intense bremsstrahlung using a superconducting electron linear accelerator, the production of positrons inside the sample under study, the efficient detector setup which allows for annihilation lifetime and Doppler-broadening spectroscopy simultaneously. Selected examples of positron annihilation spectroscopy are presented.

Ion implantation of58Co for positron-annihilation Doppler-broadening measurements

1981 ◽  
Vol 24 (1) ◽  
pp. 67-69 ◽  
Author(s):  
M. J. Fluss ◽  
M. K. Chason ◽  
J. L. Lerner ◽  
D. G. Legnini ◽  
L. C. Smedskjaer
Keyword(s):  
Ion Implantation ◽  
Positron Annihilation ◽  
Doppler Broadening
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