Simplified pseudopotential expansion theory for Al-Li alloys

Journal Article · Sat Jul 15 04:00:00 EDT 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.40.980· OSTI ID:6095730

Lu, D; Carlsson, A E

A new pseudopotential expansion theory is developed fornearly-free-electron alloys. This theory includes local-density-dependentcorrections to the usual pair potentials, to take into account long-wavelengthcharge-density fluctuations. A simplified treatment of the nonlocality of thepseudopotential is presented as well. Using this theory, the heat of formationand lattice constant are calculated for several ordered and disordered phasesof Al-Li alloys. The importance of the local-density correction and thenonlocal pseudopotential terms to the atomic bonding in these alloys isanalyzed, and the results are compared with experiments. The dominantexothermic contribution to the heat of formation comes from the nonlocality ofthe Li pseudopotential. Inclusion of the local-density and nonlocalpseudopotential terms results in considerably improved heats of formation. Theconcentration dependence of the calculated heats of formation and orderingenergy is consistent with experiment and more accurate density-functionalband-structure calculations. The results for the lattice constants of theordered compounds agree well with experiment, and the experimentally observedlattice contractions of the solid solutions are also found. However, thefailure of our method in constructing an accurate phase diagram from thecalculated heats of formation indicates that further improvements, includinghigher-order terms in the strong Al pseudopotential, are needed.

• Research Organization: Department of Physics, Washington University, St. Louis, Missouri 63130(US)
• OSTI ID: 6095730
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 40:2; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
BAND THEORY
DENSITY
ENTHALPY
FORMATION HEAT
FUNCTIONALS
FUNCTIONS
LATTICE PARAMETERS
LITHIUM ALLOYS
PHYSICAL PROPERTIES
POTENTIALS
QUANTITY RATIO
REACTION HEAT
THERMODYNAMIC PROPERTIES