Formation and stability of metastable structures and amorphous phases in Pu-V, Pu-Ta, and Pu-Yb systems with positive heats of mixing
- Lawrence Livermore National Lab., CA (United States)
- Los Alamos National Lab., NM (United States)
- Carnegie Mellon Univ., Pittsburgh, PA (United States)
The triode sputtering technique with a split-target'' arrangement was used to obtain metastable crystalline and amorphous phases in the Pu-V, Pu-Ta, and Pu-Yb systems. The proposed phase diagrams for these systems all exhibit liquid immiscibility. The heats of mixing are estimated to be highly positive, and the atomic radii of the component atoms differ by at least 10 pct. Extended amorphous and body-centered cubic (bcc) solid-solution regions were observed in the Pu-V and Pu-Ta systems. The corresponding lattice parameters appear to follow in each case an assumed Vegard's Law extension. In the Pu-Yb system, no amorphous phase was obtained, but an extended face-centered cubic (fcc) solid-solution region was observed with a large positive deviation of the lattice parameter from a linear Vegard's Law between the pure fcc components. The observed ranges of amorphous and metastable solid-solution phases have been interpreted in terms of predicated heats of formation for these phases using Miedema's thermodynamic approximations that include chemical, elastic, and structural contributions. The effect of the high deposition rates on the formation of amorphous and metastable phases has also been considered.
- DOE Contract Number:
- W-7405-ENG-48; W-7405-ENG-36
- OSTI ID:
- 7167720
- Journal Information:
- Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 25:8; ISSN 0360-2133
- Country of Publication:
- United States
- Language:
- English
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