Study of Grain Refinement in Al Alloy 2519 Using Backscattering Orientation-Contrast Mode in the Scanning Electron Microscope PDF Download
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Category :
Languages : en
Pages : 57
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The effects of variations in thermomechanical processing (TMP) parameters on grain refinement in 2519 A1-Cu alloy were studied. Refined grains enhance tensile ductility and are a prerequisite for superplastic response. The TMP variables were adjusted based on panicle stimulated nucleation (PSN) theory. Process modifications included increased initial overaging time and decreased subsequent warm rolling temperatures. Backscatter orientation-contrast (BSOC) techniques for the scanning electron microscope (SEM) were developed to achieve grain-orientation contrast An accelerating voltage of 5KV resulted in increased intensities for atomic number and orientation contrast. Both grains and theta- phase (A12Cu) precipitates were revealed on the same micrograph at higher resolutions than attainable in the optical microscope. Quantitative data from micrographs were obtained using image analysis methods. A method based on statistical considerations was developed to determine an approximate critical theta-phase particle diameter (d sub crit) for PSN. The theta-phase particle distribution was shown to be an important factor for grain refinement via PSN.
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Category :
Languages : en
Pages : 57
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Book Description
The effects of variations in thermomechanical processing (TMP) parameters on grain refinement in 2519 A1-Cu alloy were studied. Refined grains enhance tensile ductility and are a prerequisite for superplastic response. The TMP variables were adjusted based on panicle stimulated nucleation (PSN) theory. Process modifications included increased initial overaging time and decreased subsequent warm rolling temperatures. Backscatter orientation-contrast (BSOC) techniques for the scanning electron microscope (SEM) were developed to achieve grain-orientation contrast An accelerating voltage of 5KV resulted in increased intensities for atomic number and orientation contrast. Both grains and theta- phase (A12Cu) precipitates were revealed on the same micrograph at higher resolutions than attainable in the optical microscope. Quantitative data from micrographs were obtained using image analysis methods. A method based on statistical considerations was developed to determine an approximate critical theta-phase particle diameter (d sub crit) for PSN. The theta-phase particle distribution was shown to be an important factor for grain refinement via PSN.
Author: Jeffrey Robert Dunlap
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Category :
Languages : en
Pages : 51
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Category : Aeronautics
Languages : en
Pages : 556
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Author: Peter Joseph Zohorsky
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Category :
Languages : en
Pages : 0
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This study examines the effects of pre-strain deformation temperature, overaging temperature, and other variations in thermomechanical processing (TMP) on the mean size and size distribution of q-phase precipitate particles in Al alloy 2519. Examination was performed using the scanning electron microscope in the backscattered imaging mode and quantitative image analysis methods were employed. The goal was to find a combination of TMP parameters which produces q-phase particles exceeding a critical diameter for particle stimulated nucleation (PSN) of recrystallization. A necessary prerequisite for superplasticity is a uniformly fine, equiaxed grain size and PSN is theorized to be capable of such grain refinement. Such a microstructure has been developed in Aluminum alloys containing large second phase particles when the alloys are subjected to cold work and recrystallization treatments.
Author: Peter Joseph Zohorsky
Publisher:
ISBN:
Category :
Languages : en
Pages : 59
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This study examines the effects of pre-strain deformation temperature, overaging temperature, and other variations in thermomechanical processing (TMP) on the mean size and size distribution of q-phase precipitate particles in Al alloy 2519. Examination was performed using the scanning electron microscope in the backscattered imaging mode and quantitative image analysis methods were employed. The goal was to find a combination of TMP parameters which produces q-phase particles exceeding a critical diameter for particle stimulated nucleation (PSN) of recrystallization. A necessary prerequisite for superplasticity is a uniformly fine, equiaxed grain size and PSN is theorized to be capable of such grain refinement. Such a microstructure has been developed in Aluminum alloys containing large second phase particles when the alloys are subjected to cold work and recrystallization treatments.
Author: Sade H Shafer
Publisher: Springer Science & Business Media
ISBN:
Category : Education
Languages : en
Pages : 440
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Cited in Sheehy, Chen, and Hurt . Volume 38 (thesis year 1993) reports a total of 13,787 thesis titles from 22 Canadian and 164 US universities. As in previous volumes, thesis titles are arranged by discipline and by university within each discipline. Any accredited university or college with a grad
Author: Steven L. Stancy
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ISBN:
Category :
Languages : en
Pages : 0
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The first part of this study involved determining the mechanism by which elevated-temperature deformation occurred for selected tensile specimens from previous research on thermomechanically processed Al2519 alloy. Microtexture information in the form of discrete pole figures indicated that the most highly superplastic material had completely recrystallized and deformed via grain boundary sliding, whereas material that did not display superplastic behavior deformed via slip. The second part of the study was designed to achieve further refinement of the microstructure of Al2519 using the particle stimulated nucleation (PSN) model as a guide. Using the overaging parameters of the thermomechanical process (TMP) that had yielded the greatest elongation in previous work, additional material was processed but with varying final total processing strain. The resulting material was analyzed using backscatter electron (BSE) microscopy methods to evaluate the effect of total processing strain on the average grain size. The smallest true volume grain size was associated with the material with the highest total processing strain. jg p3.
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Category : Science
Languages : en
Pages : 1690
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Author: Steven L. Stancy
Publisher:
ISBN:
Category :
Languages : en
Pages : 53
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Book Description
The first part of this study involved determining the mechanism by which elevated-temperature deformation occurred for selected tensile specimens from previous research on thermomechanically processed Al2519 alloy. Microtexture information in the form of discrete pole figures indicated that the most highly superplastic material had completely recrystallized and deformed via grain boundary sliding, whereas material that did not display superplastic behavior deformed via slip. The second part of the study was designed to achieve further refinement of the microstructure of Al2519 using the particle stimulated nucleation (PSN) model as a guide. Using the overaging parameters of the thermomechanical process (TMP) that had yielded the greatest elongation in previous work, additional material was processed but with varying final total processing strain. The resulting material was analyzed using backscatter electron (BSE) microscopy methods to evaluate the effect of total processing strain on the average grain size. The smallest true volume grain size was associated with the material with the highest total processing strain. jg p3.
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Category : Government reports announcements & index
Languages : en
Pages : 1832
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