Phase stability and electronic structure of ScAl sub 3 and ZrAl sub 3 and of Sc-stabilized cubic ZrAl sub 3 precipitates

Journal Article · Fri Jun 15 04:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.12553· OSTI ID:7025583

Xu, J ^[1]; Freeman, A J ^[2]

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1. Department of Physics and Astronomy, Northwestern University, Evanston, IL (USA) Shanghai Institute of Metallurgy, Academy of Sciences of China, Shanghai 200050 (China)
2. Department of Physics and Astronomy, Northwestern University, Evanston, IL (USA)

The structural stability and the electronic structure of ScAl{sub 3} were studied using an all-electron, total-energy, local-density approach. The calculated results show that ScAl{sub 3} in the {ital L}1{sub 2} structure is energetically favored compared with the {ital D}0{sub 22} structure by about 0.42 eV per formula unit. The calculated lattice constant (4.055 A) is in fairly good agreement with experiment (4.10 A). As a comparison, the calculated electronic and cohesive properties for ZrAl{sub 3} in its metastable {ital L}1{sub 2} and {ital D}0{sub 22} phases are also presented. It is argued, on the basis of density-of-states results, that a cubic Zr{sub 1{minus}{ital x}}Sc{sub {ital x}}Al{sub 3} compound (and also Ti{sub 1{minus}{ital x}}Sc{sub {ital x}}Al{sub 3}) might be a good candidate as a dispersed phase in the aluminum alloys for elevated temperature applications. To test this prediction, we determined the electronic structure and the stability of Sc-stabilized cubic (Zr{sub 0.5}Sc{sub 0.5})Al{sub 3} using the same total-energy approach. The calculated total energy for (Zr{sub 0.5}Sc{sub 0.5})Al{sub 3}, which is about 0.24 eV per unit cell lower than the sum of the total energies of ZrAl{sub 3} and ScAl{sub 3}, clearly indicates that cubic (Zr{sub 0.5}Sc{sub 0.5})Al{sub 3} is energetically favored compared with a mixture of its constituents. Finally, an analysis of the results indicates that the stability of the aluminides appears to be understood in the rigid-band sense in terms of the band filling of the bonding states.

• OSTI ID: 7025583
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:18; ISSN PRBMD; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRONIC STRUCTURE
LATTICE PARAMETERS
PHASE STABILITY
SCANDIUM ALLOYS
STABILITY
TEMPERATURE DEPENDENCE
ZIRCONIUM ALLOYS