الفهرس 
Chapter 1 IntroductionOnly 14 pages are availabe for public view
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Abstract
Aluminum alloys have been employed as the primary structural material for medium-to high-speed commercial passenger craft traveling on short sea routes since the early 1990s. Aluminum alloys have been developed to balancing the production cost with performance and provide a combination of different properties. Aluminum alloys (1050, 5251, and 7075) are frequently employed for many high-technology applications due to their high mechanical strength to weight ratio, but they are still the focus of several studies looking for ways to improve their mechanical properties.
One of the nuclear methods that are used in materials science is called the positron annihilation technique (PAT). It acts an essential part in defect spectroscopy. PAT is the most powerful method for identifying the defects on the atomic scale also determines their concentration with high accuracy. Almost all positron annihilation experiments use the properties of gamma annihilation reaction. Various PAT exist, among them Doppler broadening technique (DBT) which is used in this work can determine the electron momentum in the direction of annihilation in this work. This technique has been used to determine the defect properties for the 1050, 5251, and 7075 wrought Al-alloys under irradiation and plastic deformation effects. The positron Annihilation parameters such as positron trapping rate can be determined in addition to the defect properties such as the defect density, dislocation density, stored dislocation energy, flow stress, micro-strain and crystallite size were estimated.
A well-known non-destructive technique for describing crystalline and non-crystalline materials is the X-ray diffraction (XRD) method which is used in this work as a comparative technique. The X-ray diffraction technique has been widely used in recent decades to reveal the microstructure of materials both qualitatively and quantitatively. It is the perfectly suited as a probe to characterize materials because of their non-destructive nature. The lattice parameter, micro-strain and crystallite size in addition to some defect properties e.g. dislocation density, defect density, flow stress, and stored dislocation energy can be determined from analysis of XRD data by Material Analysis Using Diffraction (MAUD) program.
Using Doppler broadening technique, the crystallite size for 1050 Al-alloy increases from 0.28 µm at 100 kGy to 1.27 µm at 600 kGy and then decreases. Using X-ray diffraction, the crystallite size increases from 0.913 µm for non-irradiated sample to 1.36 µm after irradiated sample up to 600 kGy and then decreases. Stored dislocation energy decreases exponential from 1.12 kJ / m3 at 100 kGy to 0.127 kJ / m3 at 600 kGy using DBT, on other hand it decreases exponential from 22.7 kJ / m3 for non-irradiated sample to 6.45 kJ / m3 at 600 kGy using XRD.
Using Doppler broadening technique, the crystallite size for 5251 Al-alloy increases from 0.23 µm at 100 kGy to 1.46 µm at 600 kGy and then decreases. Using X-ray diffraction, the crystallite size increases from 0.11 µm for non-irradiated sample to 1.31 µm after irradiated sample up to 600 kGy and then decreases. Stored dislocation energy decreases exponential from 1.78 kJ / m3 at 100 kGy to 0.11 kJ / m3 at 600 kGy using DBT, on other hand it decreases exponential from 334.95 kJ / m3 for non-irradiated sample to 9.42 kJ / m3 at 600 kGy using XRD.
Using Doppler broadening technique, the crystallite size for 7075 Al-alloy increases from 0.24 µm at 100 kGy to 0.371 µm at 400 kGy and then decreases. Using X-ray diffraction, the crystallite size increases from 1.18 µm for non-irradiated sample to 1.6 µm after irradiated sample up to 400 kGy and then decreases. Stored dislocation energy decreases exponential from 1.22 kJ / m3 at 100 kGy to 0.5 kJ / m3 at 400 kGy using DBT, on other hand it decreases exponential from 14.4 kJ / m3 for non-irradiated sample to 3.89 kJ / m3 at 400 kGy using XRD.
Doppler broadening technique (DBT) and X-ray diffraction (XRD) technique were also used to examine the effect of plastic deformation (cold work) on 7075 Al-alloy. The crystallite size decreases exponentially from 0.205 µm to 0.15 µm after mechanical deformation using Doppler broadening technique, on other hand by it decreases from 1.23 µm to 0.14 µm using X-ray diffraction. Stored dislocation energy of 7075 Al-alloy increases from 1.98 kJ / m3 at 1.04% degree of deformation to reach 55.3 kJ / m3 at 14.95% degree of deformation by DBT, meanwhile if increases from 2.62 kJ / m3 at 0% degree of deformation to reach 185 kJ / m3 at 13.68% degree deformation using XRD.
Finally, DBT and XRD measurements showed good ability to determine a lot of defect and structural properties for the studied alloys (1050, 5251, and 7075) Al-alloys as a function of irradiation doses and plastic deformation.