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You searched for +publisher:"University of North Texas" +contributor:("Srinivilliputhur, Srinivasan G."). One record found.

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University of North Texas

1. Gwalani, Bharat. Developing Precipitation Hardenable High Entropy Alloys.

Degree: 2017, University of North Texas

High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi2 (0 < x < 1.5) complex concentrated alloys as a candidate system. The composition gradient has been achieved from CrCuFeNi2 to Al1.5CrCuFeNi2 over a length of ~25 mm, deposited using the laser engineered net shaping process from a blend of elemental powders. With increasing Al content, there was a gradual change from an fcc-based microstructure (including the ordered L12 phase) to a bcc-based microstructure (including the ordered B2 phase), accompanied with a progressive increase in microhardness. Based on this combinatorial assessment, two promising fcc-based precipitation strengthened systems have been identified; Al0.3CuCrFeNi2 and Al0.3CoCrFeNi, and both compositions were subsequently thermo-mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1CoCrFeNi (3% Al (at%)) to Al0.3CoCrFeNi. (7% Al (at%)). Furthermore, Al addition leads to the precipitation of highly refined ordered L12 (γ′) and B2 precipitates in Al0.3CoCrFeNi. A detailed investigation of precipitation of the ordered phases in Al0.3CoCrFeNi and their thermal stability is done using atom probe tomography (APT), transmission electron microscopy (TEM) and Synchrotron X-ray in situ and ex situ analyses. The alloy strengthened via grain boundary strengthening following the Hall-Petch relationship offers a large increment of strength with small variation in grain size. Tensile strength of the Al0.3CoFeNi is increased by 50% on precipitation fine-scale γ′ precipitates. Furthermore, precipitation of bcc based ordered phase B2 in Al0.3CoCrFeNi can further strengthen the alloy. Fine-tuning the microstructure by thermo-mechanical treatments achieved a wide range of mechanical properties in the same alloy. The Al0.3CoCrFeNi HEA exhibited ultimate tensile strength (UTS) of ~250 MPa and ductility of ~65%; a UTS of ~1100 MPa and ductility of ~30%;… Advisors/Committee Members: Banerjee, Rajarshi, Srinivilliputhur, Srinivasan G., Young, Marcus L., Reidy, Rick, Mukherjee, Sundeep.

Subjects/Keywords: High Entropy Alloy; Precipitation Hardening; Atom Probe Tomography, Additive Manufacturing; Engineering, Materials Science

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

APA (6th Edition):

Gwalani, B. (2017). Developing Precipitation Hardenable High Entropy Alloys. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc1011755/

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):

Gwalani, Bharat. “Developing Precipitation Hardenable High Entropy Alloys.” 2017. Thesis, University of North Texas. Accessed October 28, 2020. https://digital.library.unt.edu/ark:/67531/metadc1011755/.

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

MLA Handbook (7th Edition):

Gwalani, Bharat. “Developing Precipitation Hardenable High Entropy Alloys.” 2017. Web. 28 Oct 2020.

Vancouver:

Gwalani B. Developing Precipitation Hardenable High Entropy Alloys. [Internet] [Thesis]. University of North Texas; 2017. [cited 2020 Oct 28]. Available from: https://digital.library.unt.edu/ark:/67531/metadc1011755/.

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

Council of Science Editors:

Gwalani B. Developing Precipitation Hardenable High Entropy Alloys. [Thesis]. University of North Texas; 2017. Available from: https://digital.library.unt.edu/ark:/67531/metadc1011755/

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

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