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You searched for +publisher:"University of North Texas" +contributor:("Fraser, Hamish"). Showing records 1 – 2 of 2 total matches.

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University of North Texas

1. Devaraj, Arun. Phase Separation and Second Phase Precipitation in Beta Titanium Alloys.

Degree: 2011, University of North Texas

The current understanding of the atomic scale phenomenon associated with the influence of beta phase instabilities on the evolution of microstructure in titanium alloys is limited due to their complex nature. Such beta phase instabilities include phase separation and precipitation of nano-scale omega and alpha phases in the beta matrix. The initial part of the present study focuses on omega precipitation within the beta matrix of model binary titanium molybdenum (Ti-Mo) alloys. Direct atomic scale observation of pre-transition omega-like embryos in quenched alloys, using aberration-corrected high resolution scanning transmission electron microscopy and atom probe tomography (APT) was compared and contrasted with the results of first principles computations performed using the Vienna ab initio simulation package (VASP) to present a novel mechanism of these special class of phase transformation. Thereafter the beta phase separation and subsequent alpha phase nucleation in a Ti-Mo-Al ternary alloy was investigated by coupling in-situ high energy synchrotron x-ray diffraction with ex-situ characterization studies performed using aberration corrected transmission electron microscopy and APT to develop a deeper understanding of the mechanism of transformation. Subsequently the formation of the omega phase in the presence of simultaneous development of compositional phase separation within the beta matrix phase of a Ti-10V-6Cu (wt%) alloy during continuous cooling has been investigated using a combination of transmission electron microscopy and atom probe tomography. The results of these investigations provided novel insights into the mechanisms of solid-state transformations in metallic systems by capturing the earliest stages of nucleation at atomic to near atomic spatial and compositional resolution. Advisors/Committee Members: Banerjee, Rajarshi, Srivilliputhur, Srinivasan, Needleman, Alan, Nag, SoumyA, Fraser, Hamish.

Subjects/Keywords: Titanium alloys; phase transformation; phase separation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Devaraj, A. (2011). Phase Separation and Second Phase Precipitation in Beta Titanium Alloys. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc67975/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Devaraj, Arun. “Phase Separation and Second Phase Precipitation in Beta Titanium Alloys.” 2011. Thesis, University of North Texas. Accessed November 29, 2020. https://digital.library.unt.edu/ark:/67531/metadc67975/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Devaraj, Arun. “Phase Separation and Second Phase Precipitation in Beta Titanium Alloys.” 2011. Web. 29 Nov 2020.

Vancouver:

Devaraj A. Phase Separation and Second Phase Precipitation in Beta Titanium Alloys. [Internet] [Thesis]. University of North Texas; 2011. [cited 2020 Nov 29]. Available from: https://digital.library.unt.edu/ark:/67531/metadc67975/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Devaraj A. Phase Separation and Second Phase Precipitation in Beta Titanium Alloys. [Thesis]. University of North Texas; 2011. Available from: https://digital.library.unt.edu/ark:/67531/metadc67975/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of North Texas

2. Soni, Vishal. Phase Transformations in Refractory High Entropy Alloys.

Degree: 2019, University of North Texas

High entropy alloys (HEAs) based on refractory elements have shown a great potential for high temperature structural applications. In particular, the ones containing Al, exhibits a microstructure similar to the γ-γ' in Ni-based superalloys. While these alloys exhibit impressive strengths at room temperature (RT) and at elevated temperatures, the continuous B2 matrix in these alloys is likely to be responsible for their brittle behavior at RT. Phase stability of five such alloys are studied by thermo-mechanical treatments and characterization techniques using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two of these alloys showed an inverted microstructure, where the disordered BCC phase becomes continuous, and therefore, they were characterized in detail using SEM, TEM, atom probe tomography (APT) and synchrotron x-ray diffraction experiments. The phenomenon of phase inversion lead to a better combination of strength and ductility as compared to the non-inverted microstructure.To enhance the stability of B2 intermetallic phase which provides the strength when present in a BCC matrix, multicomponent B2 phase compositions stable at 1000°C in some of the above studied alloys, were melted separately. The aim was to establish a single phase B2 at 1000°C and understand the mechanical behavior of these single-phase multicomponent B2 intermetallic alloys. These alloys exhibited a ductile behavior under compression and retained ~1 GPa yield strength at temperature up to 600°C. The ductile nature of these alloys is attributed to the change in bonding nature form directional to metallic bonding, possibly resulting from a significantly high configurational entropy compared to binary or ternary stoichiometric B2 compounds. Advisors/Committee Members: Banerjee, Rajarshi, Srivilliputhur, Srinivasan G., Mishra, Rajiv S., Mukherjee, Sundeep, Scharf, Thomas, Fraser, Hamish.

Subjects/Keywords: phase; microscopy

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Soni, V. (2019). Phase Transformations in Refractory High Entropy Alloys. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc1538735/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Soni, Vishal. “Phase Transformations in Refractory High Entropy Alloys.” 2019. Thesis, University of North Texas. Accessed November 29, 2020. https://digital.library.unt.edu/ark:/67531/metadc1538735/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Soni, Vishal. “Phase Transformations in Refractory High Entropy Alloys.” 2019. Web. 29 Nov 2020.

Vancouver:

Soni V. Phase Transformations in Refractory High Entropy Alloys. [Internet] [Thesis]. University of North Texas; 2019. [cited 2020 Nov 29]. Available from: https://digital.library.unt.edu/ark:/67531/metadc1538735/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Soni V. Phase Transformations in Refractory High Entropy Alloys. [Thesis]. University of North Texas; 2019. Available from: https://digital.library.unt.edu/ark:/67531/metadc1538735/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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