A Conceptual Modelling of the Tetragonality of L10 (AuCu-I type) Intermetallics
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Subramanian Raju
Abstract
The systematics of tetragonality in L10 (AuCu-I) type intermetallics is analysed by means of a structural mapping procedure. It is found that the Miedema parameters (metallic electronegativity and electron density at the Wigner-Seitz cell surface) order the tetragonality systematics into two broad classes, exhibited respectively by transition metal compounds and by transition – nontransition type mixed compounds. In the former category, the axial ratio (c/a) revealed a decrease with an increase in electronegativity difference, while the reverse trend is observed for the mixed type intermetallics. The effect of ternary addition and its preferential occupation of one of the sublattices of L10 structure have been found to influence strongly the tetragonality. The observed systematics has been explained in terms of a synthesis of crystal physical and chemical viewpoints on structure and bonding in intermetallics. In particular, it is hypothesised that an antiferromagnetic like coupling between interplanar and intraplanar interactions is responsible for the relative stability of L10 over B2 (CsCl) crystal structure. It is argued that a dominantly attractive (stabilising) interlayer interaction serves to compress the lattice along the [001] axis, which is promoted by a charge transfer taking place between the constituent elements segregating to individual sublattices. On the other hand, the presence of a net repulsive interaction in the {002} planes is what is responsible for increasing the tetragonality of the lattice and pushing the structure away from a B2 packing.
This paper is dedicated to the fiftieth anniversary of Indian independence.
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© 1998 Carl Hanser Verlag, München
Articles in the same Issue
- Frontmatter
- Aufsätze
- Tracer Grain Boundary Diffusion of Silver in α-Zirconium Polycrystals
- Calorimetric Determination of the Enthalpy of Formation and the Description of the Constitutional Defects of the Ordered (Ni, Co)1–y Aly, Phase
- A Conceptual Modelling of the Tetragonality of L10 (AuCu-I type) Intermetallics
- Phase Stability of Hard Alpha in Ti-64 and Ti-17
- Phase Diagram Investigation of the Indium-Selenium System
- Evaluation of Five-component Phase Diagrams for the Analysis of Phase Composition in Al–Si Based Alloys
- The Formation of Interface Phases in the Diffusion Couple Ti–SiC
- Deformation Behavior of a Modified 9Cr–1Mo Steel Between 77 and 373 K
- The Strength of Ferrite in Annealed Armco Iron and Hypoeutectoid Steels
- Notched Strength of Fabric Composite Plates with a Circular Hole
- Mitteilungen der Deutschen Gesellschaft für Materialkunde e.V.
- Personen
- Veranstaltungen
- Buchbesprechung
Articles in the same Issue
- Frontmatter
- Aufsätze
- Tracer Grain Boundary Diffusion of Silver in α-Zirconium Polycrystals
- Calorimetric Determination of the Enthalpy of Formation and the Description of the Constitutional Defects of the Ordered (Ni, Co)1–y Aly, Phase
- A Conceptual Modelling of the Tetragonality of L10 (AuCu-I type) Intermetallics
- Phase Stability of Hard Alpha in Ti-64 and Ti-17
- Phase Diagram Investigation of the Indium-Selenium System
- Evaluation of Five-component Phase Diagrams for the Analysis of Phase Composition in Al–Si Based Alloys
- The Formation of Interface Phases in the Diffusion Couple Ti–SiC
- Deformation Behavior of a Modified 9Cr–1Mo Steel Between 77 and 373 K
- The Strength of Ferrite in Annealed Armco Iron and Hypoeutectoid Steels
- Notched Strength of Fabric Composite Plates with a Circular Hole
- Mitteilungen der Deutschen Gesellschaft für Materialkunde e.V.
- Personen
- Veranstaltungen
- Buchbesprechung
