Ductility and fracture in L1[sub 2] intermetallic alloys
This paper provides a comprehensive review of the ductility and fracture in Ni[sub 3]Al, was thought to have intrinsically brittle grain boundaries. Because of the dramatic effect boron has on the grain boundaries, much work has focused on analysis of the details of the grain boundary chemistry and structure with and without boron. We now know ductilities of up to 50% are possible in boron-free material, given a defect-free specimen tested in an atmosphere with as little water vapor or hydrogen as possible. Another group of L1[sub 2], alloys, such as Al[sub 3]Sc and alloys based on the trialuminide Al[sub 3]Ti, currently appear to be intrinsically brittle, failing by cleavage with fracture toughness values of around 2 to 3 MPa[center dot]m[sup 1/2]. These alloys deform by the expected slip systems, [l brace]111[r brace]<110>, that provide sufficient deformation modes that should allow ductile behavior. These alloys are generally rather soft with yield strengths as low as 200 MPa and hardnesses as low as 150 DPH, suggesting that dislocation generation and motion is fairly easy in these materials. While a low cleavage energy and a high modulus appear to be the fundamental cause for the complete lack of ductility, the possibility exits that they too are not intrinsically brittle.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7019335
- Report Number(s):
- CONF-920621-1; ON: DE93001644
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
DUCTILITY
FRACTURE PROPERTIES
GRAIN BOUNDARIES
INTERMETALLIC COMPOUNDS
LINE DEFECTS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
TENSILE PROPERTIES
TITANIUM ALLOYS