Activation Enthalpy of Dislocation Migration in Aircraft (Aerospace) (2024) Alloy by Positron Spectroscopy

2008 ◽  
Vol 278 ◽  
pp. 11-14 ◽  
Author(s):  
M.A. Abdel-Rahman ◽  
M.S. Abdallah ◽  
N.M. Hassan ◽  
Emad A. Badawi
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Positron Annihilation ◽  
Point Defects ◽  
Isothermal Annealing ◽  
Activation Enthalpy ◽  
Positron Annihilation Lifetime ◽  
Nuclear Techniques ◽  
Positron Spectroscopy ◽  
2024 Alloy

Positron annihilation lifetime is one of the most important nuclear techniques, used to study the isochronal and isothermal annealing in one of the most important engineering aluminum alloys which is 2024 alloy. Samples of 25 % deformation have been used for these studies. Two recovery stages during the isochronal annealing [1] were observed which were ascribed to the recovery of point defects and dislocations introduced by the deformation. The isothermal annealing measurements were performed at 583, 603, 623 and 643 K from which the activation energy obtained was 1.24 ± 0.08 eV.

Probing the Activation Migration Enthalpies of Dislocations in 2024 Aircraft Material Using Nuclear and Electrical Techniques

2011 ◽  
Vol 316-317 ◽  
pp. 119-126 ◽  
Author(s):  
M.A. Abdel-Rahman ◽  
N.A. Kamel ◽  
Abdullah A. Refeay ◽  
Emad A. Badawi
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Positron Annihilation ◽  
Isothermal Annealing ◽  
Materials Science ◽  
Thickness Reduction ◽  
Electrical Measurements ◽  
Positron Annihilation Lifetime ◽  
Nuclear Techniques ◽  
Aircraft Material

Positron annihilation lifetime (PAL) measurement is one of the most important nuclear techniques used in materials science. Electrical measurements are also used in materials science. Both PAL and electrical measurements were used here to determine the activation energy of migration of dislocations in one of the most important engineering aluminum alloys: 2024. Samples of 25% deformed (thickness reduction) material have been used for these studies. The isothermal annealing measurements were performed at 583, 603, 623 and 643K for both techniques. The activation energy of migration of the dislocation was found to be equal to 1.24 ± 0.08eV by using PAL measurements and to 1.35 ± 0.01eV by using the electrical technique.

Determination of the activation enthalpy for migration of dislocations in plastically deformed 8006 Al-alloy by positron annihilation lifetime technique

2016 ◽  
Vol 30 (18) ◽  
pp. 1650110 ◽  
Author(s):  
Mohammed Salah ◽  
M. Abdel-Rahman ◽  
Emad A. Badawi ◽  
M. A. Abdel-Rahman
Keyword(s):  
Plastic Deformation ◽  
Positron Annihilation ◽  
Point Defects ◽  
Isothermal Annealing ◽  
Activation Enthalpy ◽  
Hydraulic Press ◽  
Al Alloy ◽  
Slow Cooling ◽  
Positron Annihilation Lifetime

The activation enthalpy for migration of dislocations of plastically deformed 8006 Al-alloy was investigated by positron annihilation lifetime technique. Plastic deformation using a hydraulic press produces mainly dislocations and may produce point defects. The type of defect was studied by isochronal annealing which determines the temperature range of recovery of each type. Only one type of defect (dislocations) was observed for the investigated sample and was found to be recovered within the range 455–700 K. Isothermal annealing by slow cooling was performed through this range and used in determination of the activation enthalpy of migration of dislocations which was found to be 0.26 ± 0.01 eV.

Isochronal and Isothermal Annealing of Wrought Aluminum Alloy

2011 ◽  
Vol 319-320 ◽  
pp. 37-42
Author(s):  
M.A. Abdel-Rahman ◽  
N.A. Kamel ◽  
Abdullah A. Refeay ◽  
Yahia A. Lotfy ◽  
Emad A. Badawi
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
Positron Annihilation ◽  
Material Science ◽  
Isothermal Annealing ◽  
Electrical Measurements ◽  
Positron Annihilation Lifetime ◽  
Nuclear Techniques ◽  
7075 Alloy ◽  
Wrought Aluminum

Positron annihilation lifetime (PAL) is one of the most important nuclear techniques used in material science. Electrical measurements are also used in material science. Samples of 25 % deformation have been used for these studies. Both positron annihilation lifetime and electrical measurements were used to determined the activation energy of migration the dislocation in 7075 alloy. The isothermal annealing measurements were performed at 643, 663, 683 and 703 K. The activation energy of migration the dislocation are obtained as 1.35 ± 0.16 eV and 1.25 ± 0.05 eV for positron annihilation lifetime and electrical techniques respectively.

Correlation Coefficient between Vickers Hardness and Nuclear Technique

2013 ◽  
Vol 344 ◽  
pp. 129-136
Author(s):  
Emad A. Badawi ◽  
M.A. Abdel-Rahman ◽  
Alaa El-Deen A. El-Nahhas
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloys ◽  
Severe Plastic Deformation ◽  
Positron Annihilation ◽  
Correlation Coefficient ◽  
Vickers Hardness ◽  
Positron Annihilation Spectroscopy ◽  
Age Hardening ◽  
Nuclear Technique ◽  
Positron Annihilation Lifetime

The aim of this work is to establish a correlation coefficient between the positron annihilation lifetime technique (PALS) and the Vickers hardness for the heat treatable aluminum alloys (6066, 6063).The potential of positron annihilation spectroscopy in the study of light alloys is illustrated with special regards to age hardening, severe plastic deformation, annealing and quenching in aluminum alloys. Vickers hardness is the standard method for measuring the hardness of metals, particularly those with extremely hard surfaces. Accordingly, a correlation coefficient of 90 % between τ and Hv is obtained. This correlation can help us to explain many behaviors of these alloys under deferent conditions.

Relaxation Behavior of Zr-Cu-Al Ternary Bulk Glassy Alloy Studied by Using Positron Annihilation Techniques

2010 ◽  
Vol 654-656 ◽  
pp. 1070-1073 ◽  
Author(s):  
Akito Ishii ◽  
Shinya Mineno ◽  
Akihiro Iwase ◽  
Yokoyama Yoshihiko ◽  
Toyohiko J. Konno ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Free Volume ◽  
Isothermal Annealing ◽  
Glassy Alloy ◽  
Volume Ratio ◽  
Charpy Impact ◽  
Volume Changes ◽  
Appreciable Change ◽  
Positron Annihilation Lifetime ◽  
Bulk Glassy Alloy

Zr-based bulk glassy (BG) alloys show high tensile strength and a high Charpy impact value. In this study, the free volume changes for the hypoeutectic Zr60Cu30Al10 BG alloy during isothermal annealing below glass transition temperature (Tg) have been investigated by positron annihilation lifetime and coincidence Doppler broadening (CDB) measurements. The positron lifetime of hypoeutectic and eutectic BG alloys is almost the same, although the atomic volume ratio, estimated by the density for the eutectic BG alloy is different from that for the hypoeutectic BG alloy. The CDB spectra show a marked difference between eutectic and hypoeutectic BG alloys; that is, the spectrum of the hypoeutectic BG alloy is closes to that of Zr metal than that of the eutectic BG alloy. This result exhibits that the elemental fraction of Zr atoms around free volume in hypoeutectic BG alloy is greater than that in eutectic BG alloy. The CDB ratio profiles for the hypoeutectic BG alloy during annealing shows no appreciable change. The same trend was observed in the eutectic BG alloy.

Estimating the Activation Enthalpy for Defect Formation in 5754 Alloys by Using Nuclear, Electrical and Mechanical Methods

2012 ◽  
Vol 329 ◽  
pp. 29-33 ◽  
Author(s):  
Alaa M. Ibrahim ◽  
E.M. Hassen ◽  
M. A. Abdel-Rahman ◽  
Emad A. Badawi
Keyword(s):  
Positron Annihilation ◽  
Defect Formation ◽  
Activation Enthalpy ◽  
Formation Enthalpy ◽  
Quenching Rate ◽  
Positron Annihilation Lifetime ◽  
Self Diffusion ◽  
Mechanical Methods ◽  
Positron Annihilation Study ◽  
Induced Defects

The Positron Annihilation Lifetime Technique (PALT) Is One of the Most Important Nuclear Non-Destructive Techniques. it Was Used to Study the Activation Enthalpy for Defect Formation in 5754 Alloy. Quenching Experiments Were Usually Performed on Thin Specimens to Ensure a Uniform Quenching Rate throughout the Specimen. from such Measurements, it Is Possible to Deduce the Vacancy Formation Enthalpy which, in Combination with the Results of Self-Diffusion Measurements, Gives a Value for the Migration Enthalpy of the Vacancy. these Are Very Important Quantities in the Study of the Annealing of Irradiation-Induced Defects. the Use of the Quenching Technique in the Positron Annihilation Study Has the Advantage that it Allows a Distinction to Be Made between Vacancies and Dislocations. Correlations between Nuclear, Electrical and Mechanical Methods Have Been Carried Out after Quenching.

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.

Positron Lifetime in Deformed AlSi10.9Mg0.17Sr0.06 Alloys

2007 ◽  
Vol 261-262 ◽  
pp. 55-60 ◽  
Author(s):  
M.A. Abdel-Rahman ◽  
M.S. Abdallah ◽  
Emad A. Badawi
Keyword(s):  
Dislocation Density ◽  
Positron Annihilation ◽  
Material Science ◽  
Positron Lifetime ◽  
Defect Concentration ◽  
Positron Annihilation Lifetime Spectroscopy ◽  
Positron Annihilation Lifetime ◽  
Nuclear Techniques ◽  
Mean Lifetime ◽  
The Mean

Positron annihilation lifetime spectroscopy (PALS) is one of the nuclear techniques used in material science. (PALT) measurements are used to study the behaviour of the defect concentration in a set of AlSi10.9Mg0.17Sr0.06 alloys. It has been shown that positrons can become trapped at imperfect locations in solids, and that their mean lifetime can be influenced by changes in the concentration of such defects. No changes have been observed in the mean lifetime values following saturation of the defect concentration. The mean lifetime and trapping rates were studied for samples deformed up to 34.9 %. The concentrations of defects range vary from 5.194x1015 to 1.934x1018 cm-3 for thickness reductions of 2.2 to 34.9 %. The range of the dislocation density varies from 1.465x 108 to 5.454x1010 cm/cm3 over the same range of deformations.

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