Investigation of the Precipitation Behavior in Aluminum Based Alloys

Handle URI:
http://hdl.handle.net/10754/583822
Title:
Investigation of the Precipitation Behavior in Aluminum Based Alloys
Authors:
Khushaim, Muna S. ( 0000-0002-0941-7086 )
Abstract:
The transportation industries are constantly striving to achieve minimum weight to cut fuel consumption and improve overall performance. Different innovative design strategies have been placed and directed toward weight saving combined with good mechanical behavior. Among different materials, aluminum-based alloys play a key role in modern engineering and are widely used in construction components because of their light weight and superior mechanical properties. Introduction of different nano-structure features can improve the service and the physical properties of such alloys. For intelligent microstructure design in the complex Al-based alloy, it is important to gain a deep physical understanding of the correlation between the microstructure and macroscopic properties, and thus atom probe tomography with its exceptional capabilities of spatially resolution and quantitative chemical analyses is presented as a sophisticated analytical tool to elucidate the underlying process of precipitation phenomena in aluminum alloys. A complete study examining the influence of common industrial heat treatment on the precipitation kinetics and phase transformations of complex aluminum alloy is performed. The qualitative evaluation results of the precipitation kinetics and phase transformation as functions of the heat treatment conditions are translated to engineer a complex aluminum alloy. The study demonstrates the ability to construct a robust microstructure with an excellent hardness behavior by applying a low-energy-consumption, cost-effective method. The proposed strategy to engineer complex aluminum alloys is based on both mechanical strategy and intelligent microstructural design. An intelligent microstructural design requires an investigation of the different strengthen phases, such as T1 (Al2CuLi), θ′(Al2Cu), β′(Al3Zr) and δ′(Al3Li). Therefore, the early stage of phase decomposition is examined in different binary Al-Li and Al-Cu alloys together with different ternary Al-Li-Cu alloys. Atom probe tomography and statistical testing are combined to investigate the fine scale segregation effects of dilute solutes in aluminum alloys. The optimum application of atom probe tomography in a wide range of materials is enabled by the integration of a laser pulse mode in the atom probe analysis. However, the nature of the laser mechanism used during atom probe tomography analyses is still debated. Systematic investigation of the microstructural change of δ′(Al3Li) precipitates influenced by different pulsed laser energies are used to describe the important phenome associated with the laser pulse mode. In this study, atom probe tomography presented a series of snapshots during in-situ reversion of 𝛿′(Al3Li) precipitates, initiated by laser irradiation, using different laser energies for the first time. An estimation method to investigate real sample temperatures during laser-APT analyses using an interface reaction itself as a probe has been proposed. Finally, the considerable potential of aluminum liquid is demonstrated as a powerful synthesis solvent of important intermetallic phases such as: Mg2Si, Al2Mg and CaMgSi .The atom probe tomography technique is utilized to characterize the intermediate reaction steps of the flux-grown intermetallic phases. The study proposed a direct approach to investigate the involved reactions during the formation of the synthesized intermetallic phase.
Advisors:
Rothenberger, Alexander
Committee Member:
Schwingenschlögl, Udo ( 0000-0003-4179-7231 ) ; Ooi, Boon S. ( 0000-0001-9606-5578 ) ; Aljawhari, Hala
KAUST Department:
Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program
Program:
Materials Science and Engineering
Issue Date:
30-Nov-2015
Type:
Dissertation
Appears in Collections:
Dissertations; Physical Sciences and Engineering (PSE) Division; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.advisorRothenberger, Alexanderen
dc.contributor.authorKhushaim, Muna S.en
dc.date.accessioned2015-12-13T11:39:54Zen
dc.date.available2015-12-13T11:39:54Zen
dc.date.issued2015-11-30en
dc.identifier.urihttp://hdl.handle.net/10754/583822en
dc.description.abstractThe transportation industries are constantly striving to achieve minimum weight to cut fuel consumption and improve overall performance. Different innovative design strategies have been placed and directed toward weight saving combined with good mechanical behavior. Among different materials, aluminum-based alloys play a key role in modern engineering and are widely used in construction components because of their light weight and superior mechanical properties. Introduction of different nano-structure features can improve the service and the physical properties of such alloys. For intelligent microstructure design in the complex Al-based alloy, it is important to gain a deep physical understanding of the correlation between the microstructure and macroscopic properties, and thus atom probe tomography with its exceptional capabilities of spatially resolution and quantitative chemical analyses is presented as a sophisticated analytical tool to elucidate the underlying process of precipitation phenomena in aluminum alloys. A complete study examining the influence of common industrial heat treatment on the precipitation kinetics and phase transformations of complex aluminum alloy is performed. The qualitative evaluation results of the precipitation kinetics and phase transformation as functions of the heat treatment conditions are translated to engineer a complex aluminum alloy. The study demonstrates the ability to construct a robust microstructure with an excellent hardness behavior by applying a low-energy-consumption, cost-effective method. The proposed strategy to engineer complex aluminum alloys is based on both mechanical strategy and intelligent microstructural design. An intelligent microstructural design requires an investigation of the different strengthen phases, such as T1 (Al2CuLi), θ′(Al2Cu), β′(Al3Zr) and δ′(Al3Li). Therefore, the early stage of phase decomposition is examined in different binary Al-Li and Al-Cu alloys together with different ternary Al-Li-Cu alloys. Atom probe tomography and statistical testing are combined to investigate the fine scale segregation effects of dilute solutes in aluminum alloys. The optimum application of atom probe tomography in a wide range of materials is enabled by the integration of a laser pulse mode in the atom probe analysis. However, the nature of the laser mechanism used during atom probe tomography analyses is still debated. Systematic investigation of the microstructural change of δ′(Al3Li) precipitates influenced by different pulsed laser energies are used to describe the important phenome associated with the laser pulse mode. In this study, atom probe tomography presented a series of snapshots during in-situ reversion of 𝛿′(Al3Li) precipitates, initiated by laser irradiation, using different laser energies for the first time. An estimation method to investigate real sample temperatures during laser-APT analyses using an interface reaction itself as a probe has been proposed. Finally, the considerable potential of aluminum liquid is demonstrated as a powerful synthesis solvent of important intermetallic phases such as: Mg2Si, Al2Mg and CaMgSi .The atom probe tomography technique is utilized to characterize the intermediate reaction steps of the flux-grown intermetallic phases. The study proposed a direct approach to investigate the involved reactions during the formation of the synthesized intermetallic phase.en
dc.language.isoenen
dc.subjectAluminum Alloysen
dc.subjectAtom Probeen
dc.subjectPrecipitationen
dc.subjectMicrostructureen
dc.subjectHardnessen
dc.subjectIntermetallic Phasesen
dc.titleInvestigation of the Precipitation Behavior in Aluminum Based Alloysen
dc.typeDissertationen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMaterials Science and Engineering Programen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberSchwingenschlögl, Udoen
dc.contributor.committeememberOoi, Boon S.en
dc.contributor.committeememberAljawhari, Halaen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.nameDoctor of Philosophyen
dc.person.id118307en
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