Study of Some Deformed Aluminum Alloys Using Positron Annihilation Technique
Essmat Mahmoud Hassan Sayd Ahmed;
Abstract
Point defects and dislocations are introduced into a solid by a plastic deformation at room temperature (RT). Several techniques are in use to study these defects and their behavior (e.g., migration and formation energies, recovery stages, grain size, concentrations, etc....).
Positrons annihilation have proved to be a very sensitive probe for the investigation of these defects and their propetties. Up till now however, most of the positron annihilation work has been done for pure metals. In this thesis we present posih•on annihilation measurements on some senes of commercial Aluminum Magnesium (Al-Mg) alloys, manufactory coded 5005, 5049, 5051,
5052 and 5083 with different concenh•ations 0.98, 1.9, 2.09, 2.46 and 4.44 wt.% of magnesium.
+ The posih•on annihilation mean lifetime was measured at RT for deformed Al-Mg alloys (25% thickness reduction) e.anufactmy coded 5005, 5052 and 5083 in the temperature range 300-773 K. Two stages of recovery have been observed. The first stage of recovety for the three samples was found between 350-520, 300-
480 and 300-425 K respectively, which is ath•ibuted to the annealing of point defects introduced during the deformation. After isothermal atmealing at different temperatures, an activation enthalpy for migration of point defects (vacancies) for the samples 5005, 5052 and 5083 was estimated as 0.34± 0.09 eV, 0.39± 0.11 eV and
0.42± 0.08 eV respectively. The second stage of recovety was found between 570-725, 523-773 and 500-723 K respectively for the three samples,
Positrons annihilation have proved to be a very sensitive probe for the investigation of these defects and their propetties. Up till now however, most of the positron annihilation work has been done for pure metals. In this thesis we present posih•on annihilation measurements on some senes of commercial Aluminum Magnesium (Al-Mg) alloys, manufactory coded 5005, 5049, 5051,
5052 and 5083 with different concenh•ations 0.98, 1.9, 2.09, 2.46 and 4.44 wt.% of magnesium.
+ The posih•on annihilation mean lifetime was measured at RT for deformed Al-Mg alloys (25% thickness reduction) e.anufactmy coded 5005, 5052 and 5083 in the temperature range 300-773 K. Two stages of recovery have been observed. The first stage of recovety for the three samples was found between 350-520, 300-
480 and 300-425 K respectively, which is ath•ibuted to the annealing of point defects introduced during the deformation. After isothermal atmealing at different temperatures, an activation enthalpy for migration of point defects (vacancies) for the samples 5005, 5052 and 5083 was estimated as 0.34± 0.09 eV, 0.39± 0.11 eV and
0.42± 0.08 eV respectively. The second stage of recovety was found between 570-725, 523-773 and 500-723 K respectively for the three samples,
Other data
| Title | Study of Some Deformed Aluminum Alloys Using Positron Annihilation Technique | Other Titles | دراسة عينات مشبوهة لبعض سبائك الألمومنيوم باستخدام طريقة الفناء البورزيترونى | Authors | Essmat Mahmoud Hassan Sayd Ahmed | Issue Date | 2001 |
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