Deformation mechanisms of NiAl cyclicly deformed near the brittle-to-ductile transformation temperature. Final report

Technical Report · Tue Dec 01 00:00:00 EST 1992

OSTI ID:6671620

Antolovich, S D; Saxena, A; Cullers, C

One of the ongoing challenges of the aerospace industry is to develop more efficient turbine engines. Greater efficiency entails reduced specific strength and larger temperature gradients, the latter of which means higher operating temperatures and increased thermal conductivity. Continued development of nickel-based superalloys has provided steady increases in engine efficiency and the limits of superalloys have probably not been realized. However, other material systems are under intense investigation for possible use in high temperature engines. Ceramic, intermetallic, and various composite systems are being explored in an effort to exploit the much higher melting temperatures of these systems. NiAl is considered a potential alternative to conventional superalloys due to its excellent oxidation resistance, low density, and high melting temperature. The fact that NiAl is the most common coating for current superalloy turbine blades is a tribute to its oxidation resistance. Its density is one-third that of typical superalloys and in most temperature ranges its thermal conductivity is twice that of common superalloys. Despite these many advantages, NiAl requires more investigation before it is ready to be used in engines. Binary NiAl in general has poor high-temperature strength and low-temperature ductility. On-going research in alloy design continues to make improvements in the high-temperature strength of NiAl. The factors controlling low temperature ductility have been identified in the last few years. Small, but reproducible ductility can now be achieved at room temperature through careful control of chemical purity and processing. But the mechanisms controlling the transition from brittle to ductile behavior are not fully understood. Research in the area of fatigue deformation can aid the development of the NiAl system in two ways. Fatigue properties must be documented and optimized before NiAl can be applied to engineering systems.

• Research Organization: Georgia Inst. of Tech., Atlanta, GA (United States)
• OSTI ID: 6671620
• Report Number(s): N-93-15830; NASA-CR-191649; NAS-1.26:191649; CNN: NCC3-116
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
MECHANICAL PROPERTIES
THERMODYNAMIC PROPERTIES
NICKEL ALLOYS
AEROSPACE INDUSTRY
AIRCRAFT
BEHAVIOR
BRITTLE-DUCTILE TRANSITIONS
BRITTLENESS
CONTROL
DEFORMATION
DENSITY
DESIGN
DUCTILITY
EFFICIENCY
ENGINEERING
ENGINES
FATIGUE
HEAT
HEAT RESISTING ALLOYS
MATERIALS
MELTING
OXIDATION
PROCESSING
TEMPERATURE EFFECTS
TEMPERATURE GRADIENTS
TEMPERATURE RANGE 0400-1000 K
THERMAL CONDUCTIVITY
TURBINE BLADES
ALLOYS
CHEMICAL REACTIONS
ENERGY
HEAT RESISTANT MATERIALS
INDUSTRY
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
TEMPERATURE RANGE
TENSILE PROPERTIES
360203* - Ceramics
Cermets
& Refractories- Mechanical Properties
360204 - Ceramics
Cermets
& Refractories- Physical Properties