Revealing deformation mechanisms of advanced face-centred cubic alloys at cryogenic environment via in situ neutron diffraction

Tang, Lei (2022). Revealing deformation mechanisms of advanced face-centred cubic alloys at cryogenic environment via in situ neutron diffraction. University of Birmingham. Ph.D.

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The rapid advancement of cryogenic technology is now boosting the demand for strong and ductile structural materials for low-temperature applications ranging from familiar natural gas storage/transmission to advance superconductivity realization.
In this thesis, in situ neutron diffraction and tensile testing were performed at the low-temperature range (e.g., from 373 to 10 K) to investigate the mechanical and microstructural responses of several promising face-centred cubic alloys, including high Mn steels, multi-component alloys, and an additively manufactured austenite stainless steel. Meanwhile, correlative post-mortem microscopy characterizations were utilized to reveal the microstructure evolution and assist the determination of various strengthening effects.
The qualitative and quantitative analysis revealed that the superior cryogenic mechanical performance of these advanced alloys originates from a variety of concurrent strengthening mechanisms including dislocation motion, strain-induced twinning, and phase transformation, not only building a more fundamental understanding of the strengthening effects at cryogenic conditions but also revealing the relationship among deformation mechanisms, chemical composition, stacking fault energy, and deformation temperature. This study shows a very promising way of achieving superior combinations of strengthening mechanisms by tailoring stacking fault energy, thus shedding a light on developing new alloys with lower production cost and excellent combinations of strength and ductility for cryogenic applications.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Licence: All rights reserved
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Metallurgy and Materials
Funders: Other
Other Funders: University of Birmingham, China Scholarship Council
Subjects: T Technology > TN Mining engineering. Metallurgy


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