B2 Alulinides for High Temperature Applications

1986 ◽  
Vol 81 ◽  
Author(s):  
K. Vedula ◽  
J.R. Stephes
Keyword(s):  
High Temperature ◽  
Nickel Aluminide ◽  
Titanium Aluminides ◽  
Research Center ◽  
Nasa Lewis Research ◽  
Aerospace Materials ◽  
Composite Systems ◽  
Reinforced Composite ◽  
Structural Applications ◽  
Titanium Nickel

The B2 aluminides are currently being investigated for potential high temperature structural applications. Although they are not being as actively pursued as the titanium aluminides or the L12 nickel aluminide, the B2 aluminides are very attractive from density gonsiderations. Several recent reviews of the potential for aluminides are available in literature [e.g Ref. 1,2]. Table I is a comparison of the titanium, nickel and iron aluminides of interest and shows that B2 NiAl and FeAl have the major advantage of lower densities than Ni3Al and Fe3Al. In addition, the melting point of NiAl is over 200K higher than convetitional nickel based superalloys. Hence, although low density is the prime driving force, at least in NiAl a temperature advantage is also possible. Both of these aluminides have the advantage of containing very inexpensive elements. In fact, the thrust towards the B2 aluminides evolved from a program aimed at conserving strategic aerospace materials at NASA Lewis Research Center. A recent thrust at NASA Lewis Research Center has been to consider these aluminides as matrix materials for fiber reinforced composite systems.

Thermo Mechanical Treatment of Nickel and Titanium Aluminides

2005 ◽  
Vol 237-240 ◽  
pp. 653-658
Author(s):  
Vijaya Agarwala ◽  
Joanna Karwan-Baczewska
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Nickel Aluminide ◽  
High Performance ◽  
Titanium Aluminides ◽  
Flow Behavior ◽  
Tensile Tests ◽  
Arbitrary Parameter ◽  
Average Grain Size ◽  
Structural Applications

Polycrystalline Ni3Al and TiAl are attractive materials for high temperature structural applications due to their stability in oxidizing and sulphidizing environment upto700 0 C. They possess significantly higher specific stiffness and similar specific strength as that of super alloys. Hence, these materials can replace super alloys for high temperature applications (~900°C). TiAl has lesser density and can be used for reducing component weight up to 50% and suitable for aerospace and automobile (high performance vehicles) sectors. The major difficulty for putting Ni3Al for engineering applications is its extremely low ductility and inter-granular fracture at ambient temperatures. TiAl, apart from the said brittleness it also suffers from high temperature corrosion. However the brittleness of these aluminides can be reduced by micro-alloying and by subjecting them to Thermo Mechanical Treatments, TMT. This paper deals with the recrystallization studies on nickel aluminides, deformed to different extents by rolling. The average grain size dependence with the % elongation is evaluated in the grain size range of 10-35micron. For the nickel aluminide deformed for 50% by rolling, the variation of resistivity and hardness with annealing time is determined. The homogenized TiAl samples were cold worked and annealed at 1000 0 C. Since the aluminide suffers from low ductility at room temperature, an arbitrary parameter, electrical resistivity, was chosen. Corresponding hardness values were also obtained. Finally a qualitative determination of ductility was made by studying the flow behavior of alloy around the hardness indentation. Thus a correlation was developed between resistivity, hardness and ductility values. It was then to some extent possible to investigate the TMT cycles on the microstructure and hence on the ductility of the TiAl without going for the actual tensile tests.

Recent Advances in Development and Processing of Titanium Aluminide Alloys

2000 ◽  
Vol 646 ◽  
Author(s):  
Fritz Appel ◽  
Helmut Clemens ◽  
Michael Oehring
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Environmental Stability ◽  
Physical Metallurgy ◽  
Specific Strength ◽  
Wide Range ◽  
Structural Applications ◽  
Strength And Stiffness ◽  
Nickel Base

ABSTRACTIntermetallic titanium aluminides are one of the few classes of emerging materials that have the potential to be used in demanding high-temperature structural applications whenever specific strength and stiffness are of major concern. However, in order to effectively replace the heavier nickel-base superalloys currently in use, titanium aluminides must combine a wide range of mechanical property capabilities. Advanced alloy designs are tailored for strength, toughness, creep resistance, and environmental stability. Some of these concerns are addressed in the present paper through specific comments on the physical metallurgy and technology of gamma TiAl-base alloys. Particular emphasis is placed on recent developments of TiAl alloys with enhanced high-temperature capability.

scholarly journals Advances in Thin Film Sensor Technologies for Engine Applications

1997 ◽  
Author(s):  
Jih-Fen Lei ◽  
Lisa C. Martin ◽  
Herbert A. Will
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
High Speed ◽  
Ceramic Matrix Composites ◽  
Surface Strain ◽  
Research Center ◽  
Strain Gauges ◽  
Nasa Lewis Research ◽  
Film Sensor ◽  
Thin Film Sensor

Advanced thin film sensor techniques that can provide accurate surface strain and temperature measurements are being developed at NASA Lewis Research Center. These sensors are needed to provide minimally intrusive characterization of advanced materials (such as ceramics and composites) and structures (such as components for Space Shuttle Main Engine, High Speed Civil Transport, Advanced Subsonic Transports and General Aviation Aircraft) in hostile, high-temperature environments, and for validation of design codes. This paper presents two advanced thin film sensor technologies: strain gauges and thermocouples. These sensors are sputter deposited directly onto the test articles and are only a few micrometers thick; the surface of the test article is not structurally altered and there is minimal disturbance of the gas flow over the surface. The strain gauges are palladium-13% chromium based and the thermocouples are platinum-13% rhodium vs. platinum. The fabrication techniques of these thin film sensors in a class 1000 cleanroom at the NASA Lewis Research Center are described. Their demonstration on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are discussed.

Status and Development of Nickel Aluminide (NiAl) Composites

1994 ◽  
Vol 350 ◽  
Author(s):  
R. A. Amato ◽  
J.-M. Yang
Keyword(s):  
High Temperature ◽  
Mechanical Behavior ◽  
Nickel Aluminide ◽  
Matrix Alloy ◽  
Fiber Development ◽  
Continuous Fiber ◽  
Alloy Development ◽  
New Class ◽  
Structural Applications ◽  
Key Issues

AbstractNiAl-based composites are a new class of engineering materials being developed for high temperature structural applications in oxidizing and aggressive environments. This paper discusses some of the recent advances in developing continuous fiber-reinforced polycrystalline NiAl-based composites. Several key issues including matrix alloy development, fiber development, fabrication development and mechanical behavior will be addressed.

The effect of thermal exposure on precipitation of Ti3Al(C,N) in Ti-48Al-IV-0.2C

1992 ◽  
Vol 50 (1) ◽  
pp. 22-23
Author(s):  
W.T. Donlon ◽  
W.E. Dowling ◽  
C.E. Cambell ◽  
J.E. Allison
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Titanium Aluminides ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Weight Ratio ◽  
Thermal Exposure ◽  
Treatment Temperature ◽  
Field Samples ◽  
Structural Applications

Titanium aluminides are attractive candidates for high temperature structural applications because of their high strength to weight ratio at elevated temperatures. The microstructure of these alloys consists of γ-TiAl (distorted L10 structure) , plus α2-Ti3Al (ordered DO19 structure). Varying the heat treatment temperature and cooling rate of these alloys alters the volume fraction and distribution of the γ and α2 phases. This has significant effects on the room temperature ductility. In addition, precipitation of carbides has been observed during high temperature exposure. The effect of these precipitates on the mechanical properties has yet to be determined.Figure 1 shows the general microstructure that was used for this investigation. TEM foils were prepared by electropolishing using 5% perchloric, 35% 1-butanol, 60% methanol at -40°C. No precipitates were found following heat treatment in the γ+α phase field. Samples approximately 20 mm square were thermally exposed to temperatures between 625° and 1000°C for times between 1 and 2000 hours.

Elevated Temperature Fiber Push-Out Testing

1994 ◽  
Vol 365 ◽  
Author(s):  
J.I. Eldridge
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Experimental Procedure ◽  
Composite Systems ◽  
Test Methodology ◽  
Reinforced Composite ◽  
Critical Issues ◽  
Push Out ◽  
Potential Use

ABSTRACTThe potential use of fiber-reinforced composite materials for high temperature applications makes the development of interface test methodology at those high temperatures very desirable. A facility for performing high temperature fiber push-out tests will be described with emphasis on critical issues in experimental procedure. Examples from several composite systems illustrate the temperature dependence and environmental sensitivity of fiber debonding and sliding. Interpretation of the temperature dependence will be made primarily in terms of changes in residual stresses along with additional effects due to changes in matrix ductility and interfacial wear. Examples will show that high temperature fiber push-out testing can often distinguish between chemical and frictional fiber/matrix bonding in cases where room temperature only testing cannot.

Dislocation structures in titanium aluminides deformed at 815°C

1990 ◽  
Vol 48 (4) ◽  
pp. 984-985
Author(s):  
W.T. Donlon ◽  
W.E. Dowling ◽  
J.E. Allison
Keyword(s):  
High Temperature ◽  
Automobile Industry ◽  
Titanium Aluminides ◽  
Thermomechanical Processing ◽  
High Strength ◽  
Fatigue Properties ◽  
Major Drawback ◽  
Cast Material ◽  
Heat Treated ◽  
Structural Applications

Ordered (L10) intermetallic γ-TiAl alloys are candidates for high temperature structural applications in the automobile industry because of their low density and high strength at elevated temperature. The major drawback of these materials is their low ductility at ambient temperature. Improvements in low temperature ductility may be achieved without sacrificing the desired high temperature performance by optimizing the microstructure through thermomechanical processing. This investigation measured the tensile and fatigue properties of an “as-cast” and cast plus heat treated Ti-48A1-1V-0.2C (at%) alloy at 25 and 815°C.The microstructure of both samples consisted of primary γ grains with an average intercept size of 100 μm, and regions of a γ matrix with α2 lathes. The vol% of the primary γgrains was 40% and 85% in the “as-cast” and cast plus heat treated samples, respectively. Figure 1 shows the microstructure of the “as-cast” material.

Research on High-Temperature Aerospace Materials at NASA Glenn Research Center

2013 ◽  
Vol 26 (2) ◽  
pp. 500-514 ◽  
Author(s):  
Joyce A. Dever ◽  
Michael V. Nathal ◽  
James A. DiCarlo
Keyword(s):  
High Temperature ◽  
Research Center ◽  
Aerospace Materials
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