Deformation of NiAl bicrystals. Final report, 1 June 1985-30 June 1990

Technical Report · Fri Jun 01 04:00:00 EDT 1990

OSTI ID:6345297

Miracle, D B

The glide of non-<100> dislocations at NiAl grain boundaries is proposed to account for the observed ductility of this compound near the brittle-to-ductile transition temperature. Two bicrystal orientations have been produced to investigate the activation of <111> dislocations due to the concentrated local stress at the bicrystal interface arising from elastic and plastic incompatibility. Observations of surface slip markings and TEM characterization of the dislocations responsible for bicrystal deformation have been made. The glide of <110> dislocations on (110) planes is the dominant mode of deformation in the vicinity of the oriented bicrystal interfaces investigated. It is concluded that the glide of non-<100> dislocations may contribute to the plasticity of polycrystalline NiAl in a general sense, and not just in cube-oriented single crystals where <100> slip is geometrically restricted. The dominant mode of <110> dislocation generation is the nucleation of <110> loops away from the grain boundary. The macroscopic stress required to activate these <110> dislocations, in the presence of a stress concentration such as that produced by a dislocation pile-up at a grain boundary, is the same as that required to nucleate <100> dislocations. The statistical relevance of this phenomenon as it pertains to the general deformation of NiAl polycrystals has not been established.... Nial, Nickel aluminide, Bicrystal, Deformation, Dislocation structures, Stress concentration.

• Research Organization: Wright Lab., Wright-Patterson AFB, OH (United States)
• OSTI ID: 6345297
• Report Number(s): AD-A-263139/8/XAB; WL-TR--92-4111
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals &amp; Alloys-- Structure &amp; Phase Studies
360103* -- Metals &amp; Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM COMPOUNDS
BICRYSTALS
BRITTLENESS
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTALS
DATA
DEFORMATION
DISLOCATIONS
DUCTILE-BRITTLE TRANSITIONS
DUCTILITY
ELASTICITY
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
INFORMATION
INTERFACES
INTERMETALLIC COMPOUNDS
LINE DEFECTS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
NICKEL COMPOUNDS
NUMERICAL DATA
PHYSICAL PROPERTIES
PLASTICITY
POLYCRYSTALS
SLIP
STATISTICAL DATA
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
TRANSMISSION ELECTRON MICROSCOPY