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Initial Weldability of High Entropy Alloys for High Temperature Applications

Martin, Alexander Charles

Abstract Details

2019, Master of Science, Ohio State University, Welding Engineering.
High Entropy Alloys (HEA) are a new class of alloys that was introduced in the early 2000's. These alloys are composed of five or more elements in near equiatomic ratios, with no single base element. HEAs have gained a lot of attention due to their unique or superior properties as compared to conventional alloys. However, there has been little attention paid to the welding metallurgy and weldability of HEAs. However, welding for manufacturing and repair is a key issue for structural engineering applications. This work aimed to establish an initial understanding of the welding metallurgy of HEAs, and identify any potential weldability issues with regard to weld cracking susceptibility in fusion welds. The outcomes of this initial evaluation were used to develop a methodology for rapidly screening the large compositional space of HEAs in order to find promising alloy compositions for weld applications, and ultimately to implement weldability in the early stages of HEA development. The most commonly studied equiatomic AlCoCrCuFeNi HEA was determined to have very poor weldability, due to the positive mixing enthalpy of copper and a high hardness microstructure promoted by aluminum. An improved weldability was achieved by modifying the composition to Al0.5CoCrCu0.1FeNi. Pulsed laser welding was shown to eliminate HAZ liquation cracking for AlCoCrFeNiTi HEA and reduces softening in the HAZ of Al0.5CoCrCu0.1FeNi HEA. Refractory HEA AlMo0.5NbTa0.5TiZr showed a very high susceptibility to porosity and brittle fracture, but a unique fusion zone microstructure with no cracking. A high-throughput screening based on thermodynamic modeling and experimental testing was developed in order to identify HEA compositions with promising weldability, and quickly reject alloy compositions with detrimental properties towards weldability.
Carolin Fink (Advisor)
Antonio Ramirez (Committee Member)
124 p.

Recommended Citations

Citations

  • Martin, A. C. (2019). Initial Weldability of High Entropy Alloys for High Temperature Applications [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555496040477991

    APA Style (7th edition)

  • Martin, Alexander. Initial Weldability of High Entropy Alloys for High Temperature Applications. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555496040477991.

    MLA Style (8th edition)

  • Martin, Alexander. "Initial Weldability of High Entropy Alloys for High Temperature Applications." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555496040477991

    Chicago Manual of Style (17th edition)