Evolution of Precipitates and Their Influence on the Mechanical Properties of β-Titanium Alloys Metadata

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Title

  • Main Title Evolution of Precipitates and Their Influence on the Mechanical Properties of β-Titanium Alloys

Creator

  • Author: Mantri, Srinivas Aditya
    Creator Type: Personal

Contributor

  • Chair: Banerjee, Rajarshi
    Contributor Type: Personal
  • Committee Member: Williams, James C.
    Contributor Type: Personal
  • Committee Member: Srivilliputhur, Srinivasan G.
    Contributor Type: Personal
  • Committee Member: Mishra, Rajiv
    Contributor Type: Personal
  • Committee Member: Scharf, Thomas W.
    Contributor Type: Personal
  • Committee Member: Young, Marcus L.
    Contributor Type: Personal

Publisher

  • Name: University of North Texas
    Place of Publication: Denton, Texas

Date

  • Creation: 2017-08

Language

  • English

Description

  • Content Description: Over the last few decades, body-centered-cubic (bcc) beta (β) titanium alloys have largely been exploited as structural alloys owing to the richness in their microstructural features. These features, which lead to a unique combination of high specific strength and ductility, excellent hardenability, good fatigue performance, and corrosion resistance, make these alloys viable candidates for many applications, including aerospace, automobile, and orthopedic implants. The mechanical properties of these alloys strongly depend on the various phases present; which can be controlled by thermomechanical treatments and/or alloy design. The two most important and studied phases are the metastable ω phase and the stable α phase. The present study focuses on the microstructural evolution and the mechanical behavior of these two phases in a model β-Ti alloy, binary Ti-12wt. %Mo alloy, and a commercial β-Ti alloy, β-21S. Microstructures containing athermal and isothermal ω phases in the binary Ti-12wt. %Mo alloy are obtained under specific accurate temperature controlled heat treatments. The formation and the evolution of the ω-phase based microstructures are investigated in detail via various characterization techniques such as SEM, TEM, and 3D atom probe tomography. The mechanical behavior was investigated via quasi-static tensile loading; at room and elevated temperatures. The effect of β phase stability on the deformation behavior is then discussed. Similar to the Ti-12wt. %Mo, the formation and the evolution of the athermal and isothermal ω phases in the commercial β-21S alloy was studied under controlled heat treatments. The structural and compositional changes were tracked using SEM, TEM, HR-STEM, and 3D atom probe tomography (3D-APT). The presence of additional elements in the commercial alloy were noted to make a considerable difference in the evolution and morphology of the ω phase and also the mechanical behavior of the alloys. The Portevin-Le Chatelier (PLC) like effect was observed in iii this alloy at elevated temperature and this has been attributed to the shearing of the ω precipitates and the dynamic precipitation of the α phase within these channels. The formation of the stable α phase in the commercial β-21S alloy due to the influence of precursor phases, like the metastable ω phase, is investigated. It is evident from the microstructural characterization, using SEM, TEM, HR-STEM, and 3D-APT, that the ω phase does play a role on the fine scale α precipitation. The mechanical behavior of the β+α microstructure, investigated via tensile testing, shows that these alloys are ideal candidate for precipitation hardening. The exceptional strength values obtained in this alloy have been attributed to a combination of several factors.

Subject

  • Keyword: Titanium Alloys
  • Keyword: Phase Transformation
  • Keyword: Deformation Studies
  • Keyword: EBSD
  • Keyword: TEM
  • Keyword: APT
  • Keyword: Engineering, Materials Science

Collection

  • Name: UNT Theses and Dissertations
    Code: UNTETD

Institution

  • Name: UNT Libraries
    Code: UNT

Rights

  • Rights Access: unt
  • Rights Holder: Mantri, Srinivas Aditya
  • Rights License: copyright
  • Rights Statement: Copyright is held by the author, unless otherwise noted. All rights Reserved.

Resource Type

  • Thesis or Dissertation

Format

  • Text

Identifier

  • Accession or Local Control No: submission_823
  • Archival Resource Key: ark:/67531/metadc1011759

Degree

  • Degree Name: Doctor of Philosophy
  • Degree Level: Doctoral
  • Academic Department: Department of Materials Science and Engineering
  • College: College of Engineering
  • Degree Discipline: Materials Science and Engineering
  • Degree Publication Type: disse
  • Degree Grantor: University of North Texas

Note

  • Embargo Note: Item will be restricted to campus view only for 5 years. Start date for restriction period is the first day of the month immediately following graduation month: June 1 (May graduation), September 1 (August graduation), or January 1 of following year (December graduation). Embargo expires on 2022-08-01.