On grain boundary phases in B-doped Ni sub 3 Al

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Scripta Metallurgica; (United States)

OSTI ID:5740204

Brenner, S S; Min-Jian, H ^[1]

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1. Dept. of Materials Science and Engineering, Univ. of Pittsburgh, Pittsburgh, PA (US)

Polycrystalline Ni{sub 3}Al normally fractures intergranularly with little plastic deformation. Its ductility can be greatly increased by adding small amounts of boron. Plastic tensile strains as high as 50% have been reported by C.T. Liu and coworkers. A peculiar aspect of this ductilization phenomenon is that boron is only effective in Ni-rich alloys. Much effort, both experimental and theoretical, has been expended to understand the boron effect in the hope of producing ductile intermetallics that might be even more suitable for high-temperature structural applications than Ni{sub 3}Al. It is generally agreed that the boron must be enriched at the grain boundaries in order to impart ductility to the aluminide. But this cannot be the only criterion since boron also segregates to the boundaries in Al-rich alloys which remain brittle. To find additional criteria for ductility, attention has been focused on the composition and state of ordering of the grain boundary regions. Earlier FIM/AP studies concluded that the matrix is ordered up to the boundary, at least on one side of the interface (4,8). In this paper the authors report the results of more recent work in which the authors examined the state of order on both sides of boundaries in ductile Ni{sub 3}Al and estimated the maximum width of any disordered boundary phase that would escape detection. We also discuss the occurrence of other types of grain boundary phases observed in the FIM/AP.

• OSTI ID: 5740204
• Journal Information: Scripta Metallurgica; (United States), Journal Name: Scripta Metallurgica; (United States) Vol. 24:4; ISSN 0036-9748; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
360104 -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
CHEMICAL COMPOSITION
COHERENT SCATTERING
CRYSTAL STRUCTURE
CRYSTALS
DIFFRACTION
DOPED MATERIALS
DUCTILITY
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INTERMETALLIC COMPOUNDS
MATERIALS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
ORDER-DISORDER TRANSFORMATIONS
PHASE STUDIES
PHASE TRANSFORMATIONS
POLYCRYSTALS
SCATTERING
TENSILE PROPERTIES
TRANSMISSION ELECTRON MICROSCOPY