Geometrical models for symmetrical tilt boundaries in L1/sub 2/ ordered compounds

Journal Article · Sun Feb 01 04:00:00 EST 1987 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(87)90243-4· OSTI ID:5524905

Farkas, D; Rangarajan, V

A modified hard sphere model and coincident site lattice theory were used to analyze the possible configurations of symmetrical tilt boundaries with the L1/sub 2/ structure. The minimum allowed interatomic distances used in the model were estimated from the structures of stable intermetallic phases in the corresponding binary system. Two different compounds were analyzed, Cu/sub 3/Au and Ni/sub 3/Al. For Cu/sub 3/Au, the grain boundary structures obtained were similar to those reported by other investigators for pure f.c.c. metals. Several boundaries were found to present two possible structures, differing in composition and ordering state. The contribution of disordering to the grain boundary energy was calculated in a point approximation based on the first coordination shell. For compounds of the Ni/sub 3/Al type the grain boundary structures that are most dense were found to be generally different from configuration of boundaries in pure f.c.c. metals and Cu/sub 3/Au. These configurations preserve order, but are less dense. The possibility of grain boundary ''phases'' that are not present in other f.c.c. materials may constitute an explanation for the extreme g.b. weakness observed in Ni/sub 3/Al and other L1/sub 2/ compounds with high ordering energy.

• Research Organization: Dept. of Materials Engineering, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061
• OSTI ID: 5524905
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 35:2; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
BINARY ALLOY SYSTEMS
COPPER ALLOYS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
FCC LATTICES
GOLD COMPOUNDS
GRAIN BOUNDARIES
MATHEMATICAL MODELS
MICROSTRUCTURE
NICKEL ALLOYS
STRUCTURAL CHEMICAL ANALYSIS
SYMMETRY
TRANSITION ELEMENT COMPOUNDS