Alloy Modeling and Experimental Correlation for Ductility Enhancement in Near Stoichiometric Single Crystal Nickel Aluminide
Abstract
The objective of this research was to evaluate the applicability of theoretical approaches based on first principles to understand the ductility problem in intermetallic compounds. The predictive approach is based on all electron total energy band structure calculations. Predictions were evaluated on single crystals of nickel aluminum alloys. Calculations of anti-phase boundary (APB) energy in binary NiAl and the effects of ternary alloying additions on APB energy were performed. Experimental work on the effects of Cr and V additions, predicted by the calculations to reduce APB energy, was conducted. Studies aimed at exploiting the stress induced martensite transformation in NiAl to increase low temperature toughness were also conducted. Results from the calculations were found to be in good agreement with known stoichiometric effects on the transformation in binary alloys and suggested potentially beneficial ternary and quaternary alloying additions. The investigation of the role of Chromium in promoting slip in NiAl was continued. Experiments to more fully understand this effect were performed. Additional calculations were conducted to clarify the stress induced martensite effect. Calculations aimed at understanding the role of charge density distributions and bond directionality in NiAl were also initiated. Work to determine the role of microalloying in promoting ductility in NiAl was initiated, through calculations of their effect on local charge distribution and experimental work to determine their effect on slip and fracture behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 31, 1991
- Accession Number
- ADA240151
Entities
People
- A. J. Freemen
- D. F. Lahrman
- R. D. Field
- R. Darolia
Organizations
- GE Aerospace