Dissertation
Solubility and Partition of Indium Solute Between Sublattices in the Cubic Laves Phase GdAl2
Washington State University
Doctor of Philosophy (PhD), Washington State University
2023
DOI:
https://doi.org/10.7273/000005376
Abstract
Perturbed angular correlation of gamma rays (PAC) was used for studying the solution of In atoms in the intermetallic compound GdAl2 for solute mole-fractions between 10-11 and 10-2. Measurements showed the phase boundaries of the solute-free GdAl2 to be 33.1(2) and 34.1(1) at.% Gd at a temperature of order K. In previous work, equilibrium measurements determined that the enthalpy of transfer of indium solute from the Gd-sublattice to the Al-sublattice was 0.34 eV. It is now shown that the transfer enthalpy is constant over the entire phase field, which was a surprise given that the field spans both sides of the stoichiometric composition and intrinsic defects differ on the two sides. These phase boundaries agree well with those found in a phase diagram in the literature. Mole fractions of natural In ranging from 0.05 – 2 at.% In were dissolved into GdAl2 in addition to extremely dilute 111In probes used in the PAC measurements. A linear decrease from 0.34 eV was observed in transfer enthalpy as the solute mole fraction increased, reaching 0 eV for 1.4(2) at.% In. The latter value is identified as the solubility limit for In in GdAl2 near 873 K. A thermodynamic model was developed that reproduces the decrease in transfer enthalpy. In effect, it is found that the transfer enthalpy decreased as the added solute eventually filled all lattice sites available to them, after which the solute atoms can no longer transfer. The transfer is effectively “jammed”. A novel Gd-Al-In ternary phase diagram is proposed on the basis of these measurements that shows the dominant point defects in three regimes of the single-phase field: Gd-poor, Gd-rich, and In-doped.
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Details
- Title
- Solubility and Partition of Indium Solute Between Sublattices in the Cubic Laves Phase GdAl2
- Creators
- Windy Lin Olsen
- Contributors
- Gary S Collins (Advisor)Brian A Collins (Committee Member)Matthew O Zacate (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Physics and Astronomy, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 122
- Identifiers
- 99901031240301842
- Language
- English
- Resource Type
- Dissertation