Interatomic Potentials and the Bonding Energetics of Polytetrahedral Packing in Transition Metal Alloys
The discovery of quasicrystals1, recent work on the theory of metallic glasses,2,3 and continued interest in the Frank-Kasper phases all provide impetus for understanding the bonding energetics associated with polytetrahedral atomic configurations as building blocks for complex structures. Previous theoretical work has successfully explained the observed stability regions for a few specific PTP phases4,5 (we define PTP phases to be those close packed phases in which all atoms sit at the vertices of tetrahedra, such as the Frank-Kasper phases and possibly some quasicrystals) within the framework of tight binding theory. In addition, Watson and Bennett6 have made a general empirical study of the trends in the relative stability of the majority of the Frank-Kasper phases, using atomic size concepts and d-band hole counts. In this work we provide a more general theoretical analysis, based on total energy calculations, of the factors favoring PTP over fcc packing. This analysis is directly complementary to the empirical analysis of Watson and Bennett,6 and explains empirically observed trends in the relative stability of PTP on the basis of angle-dependent effective interatomic potentials.
KeywordsMetallic Glass Transition Metal Alloy Previous Theoretical Work Close Packed Phasis Tight Binding Theory
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