FIM/atom probe analysis of grain boundaries in B-doped Ni sub 3 Al

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Scripta Metallurgica; (United States)

OSTI ID:5529359

Brenner, S S; Hua, M J ^[1]

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

High-temperature intermetallic alloys have been studied intensively during the past few years with the aim of improving their inherent brittleness. Ni{sub 3}Al has receive special attention because of the dramatic increase in its ductility that can be brought abut by small additions of boron. No special alloy preparation or heat treatment is required but the effect is only observed in Ni-rich Ni{sub 3}Al. There is little agreement on the case of the ductilization. Since single crystals of Ni{sub 3}Al are ductile while the polycrystalline material is brittle and fails intergranularly, it has always been assumed that the key to understanding the effect is the mechanical and electronic modification of the grain boundary regions by the boron. But even this consensus of opinion has been challenged by T.K. Chaki who proposed that B-doped No-rich Ni{sub 3}Al is ductile because boron and antisite nickel atoms distort the bonds and reduce the directionality of bonding thus softening the interior of the grains. This reduces the stress required to generate dislocations in adjacent grains, thereby relieving stress concentrations at the boundaries. The field-ion microscope atom probe has been one of the instruments used in the investigations of grain boundaries in Ni{sub 3}Al. In this paper the authors review the published results obtained by this technique and present some additional data obtained more recently.

• OSTI ID: 5529359
• Journal Information: Scripta Metallurgica; (United States), Journal Name: Scripta Metallurgica; (United States) Vol. 25:6; 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
ALLOYS
ALUMINIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
BRITTLE-DUCTILE TRANSITIONS
BRITTLENESS
CHEMICAL ANALYSIS
CRYSTAL STRUCTURE
CRYSTALS
DUCTILITY
GRAIN BOUNDARIES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INTERMETALLIC COMPOUNDS
ION MICROPROBE ANALYSIS
MATERIALS
MECHANICAL PROPERTIES
MICROANALYSIS
MICROSTRUCTURE
MONOCRYSTALS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NONDESTRUCTIVE ANALYSIS
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TENSILE PROPERTIES