The influence of boron segregation on the structure and mechanical properties of boundaries in bicrystals of Ni sub 3 Al

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

OSTI ID:5579611

Mills, M J; Goods, S H; Foiles, S M ^[1]; Whetstone, J R ^[2]

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1. Sandia National Labs., Livermore, CA (United States)
2. General Motors Corp., Indianapolis, IN (United States). Allison Gas Turbine Div.

This paper reports that in contrast to the high ductilities reported for single crystals of ordered ({gamma}) Ni{sub 3}Al, the ductility in polycrystalline form is extremely limited. The discovery by Aoki and Izumi that microalloying with boron greatly increases the ductility of polycrystalline Ni{sub 3}Al has initiated spirited scientific investigation into the structure and properties of grain boundaries in this material. One consequence of the addition of boron could be an increase in the cohesive properties of the grain boundaries. However, at present the most widely accepted explanation for the improved ductility of the grain boundaries is the boron cause compositional disordering of the grain boundary region. As first suggested by King and Yoo, the total number of possible dislocation reactions is generally much larger at a grain boundary in disordered ({gamma}) material (the FCC structure) than in the ordered Ll{sub 2} phase. consequently, for the disordered case, the absorption or transmission of dislocations across the boundary should be easier, large stress concentrations should not develop as readily at the boundary, and the propensity for intergranular fracture should be reduced.

• OSTI ID: 5579611
• 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
360104 -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
BORON ADDITIONS
BORON ALLOYS
BRITTLE-DUCTILE TRANSITIONS
CHEMICAL REACTIONS
CORROSION
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
CUBIC LATTICES
DUCTILITY
ELECTRON MICROSCOPY
FCC LATTICES
GRAIN BOUNDARIES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
INTERGRANULAR CORROSION
MATERIALS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
MONOCRYSTALS
MONTE CARLO METHOD
NICKEL ALLOYS
NICKEL BASE ALLOYS
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
POLYCRYSTALS
TENSILE PROPERTIES
TRANSMISSION ELECTRON MICROSCOPY