Refractory Metal/Silicide Multiphase Systems for High Temperature Structural Applications

AbstractThe fracture and fatigue behavior of refractory metal silicide alloys/composites is significantly affected by the mechanical behavior of the refractory metal phase. This paper reviews some of the balance of properties obtained in the alloys/composites based on the Nb-Si system. Since some of the alloy/composite properties are dominated by the behavior of the refractory metal phase, the paper begins with a review of data on monolithic Nb and its alloys. This is followed by presentation of results obtained on Nb-Si alloys/composites and a comparison to behavior of some other high temperature systems.

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Coating Reactions on Vanadium and V-Si-B Alloys during Powder Pack-Cementation

Materials ◽

10.3390/ma13184099 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4099

Author(s):

Georg Hasemann ◽

Chad Harris ◽

Manja Krüger ◽

John H. Perepezko

Keyword(s):

High Temperature ◽

Oxidation Resistance ◽

Refractory Metal ◽

Pack Cementation ◽

Solid Solution Phase ◽

Major Drawback ◽

Three Phase ◽

Structural Applications ◽

New Type ◽

Refractory Metal Alloys

Alloys in the V-Si-B system are a new and promising class of light-weight refractory metal materials for high temperature applications. Presently, the main attention is focused on three-phase alloy compositions that consist of a vanadium solid solution phase and the two intermetallic phases V3Si and V5SiB2. Similar to other refractory metal alloys, a major drawback is the poor oxidation resistance. In this study, initial pack-cementation experiments were performed on commercially available pure vanadium and a three-phase alloy V-9Si-5B to achieve an oxidation protection for this new type of high temperature material. This advance in oxidation resistance now enables the attractive mechanical properties of V-Si-B alloys to be used for high temperature structural applications.

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Lattice Imaging of Grain Boundaries in Ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078171 ◽

1977 ◽

Vol 35 ◽

pp. 114-115

Author(s):

D. R. Clarke ◽

G. Thomas

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Silicon Nitride ◽

Grain Boundaries ◽

High Temperature Strength ◽

Current Interest ◽

Lattice Imaging ◽

Special Significance ◽

Structural Applications ◽

Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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Crystallization sequence of an A1N-Y2O3-SiO2 glass-ceramic

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143808 ◽

1986 ◽

Vol 44 ◽

pp. 446-447

Author(s):

T.R. Dinger ◽

G. Thomas

Keyword(s):

High Temperature ◽

Glass Ceramic ◽

Crystallization Behavior ◽

High Stress ◽

Crystallization Sequence ◽

Sio2 Glass ◽

Structural Applications ◽

Ceramic Precursors

The use of Si3N4, alloys for high temperature, high stress structural applications has prompted numerous studies of the oxynitride glasses which exist as intergranular phases in their microstructures. Oxynitride glasses have been investigated recently in their bulk form in order to understand their crystallization behavior for subsequent Si3N4 applications and to investigate their worth as glass-ceramic precursors. This research investigates the crystallization sequence of a glass having a normalized composition of Y26Si30Al11 ON11 and lying in the A1N-Y2O3-SiO2 section of the Y-Si-Al-O-N system. Such glasses exist as intergranular phases in the technologically important Y2O3/Al2O3-fluxed Si3N4 alloys.

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Electron energy loss near edge structures of intermetallic alloys and grain boundaries in NiAl

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100165070 ◽

1996 ◽

Vol 54 ◽

pp. 522-523

Author(s):

G.A. Botton ◽

C.J. Humphreys

Keyword(s):

High Temperature ◽

Transition Metal ◽

Energy Loss ◽

Grain Boundaries ◽

Industrial Applications ◽

Edge Structure ◽

Structural Applications ◽

Yield Behaviour ◽

Late Transition ◽

Metal Aluminides

Transition metal aluminides are of great potential interest for high temperature structural applications. Although these materials exhibit good mechanical properties at high temperature, their use in industrial applications is often limited by their intrinsic room temperature brittleness. Whilst this particular yield behaviour is directly related to the defect structure, the properties of the defects (in particular the mobility of dislocations and the slip system on which these dislocations move) are ultimately determined by the electronic structure and bonding in these materials. The lack of ductility has been attributed, at least in part, to the mixed bonding character (metallic and covalent) as inferred from ab-initio calculations. In this work, we analyse energy loss spectra and discuss the features of the near edge structure in terms of the relevant electronic states in order to compare the predictions on bonding directly with spectroscopic experiments. In this process, we compare spectra of late transition metal (TM) to early TM aluminides (FeAl and TiAl) to assess whether differences in bonding can also be detected. This information is then discussed in terms of bonding changes at grain boundaries in NiAl.

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Phase transformation and layer evolution in molybdenum disilicide-silicon carbide nanolayered coatings

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170426 ◽

1994 ◽

Vol 52 ◽

pp. 538-539

Author(s):

H. Kung ◽

T. R. Jervis ◽

J.-P. Hirvonen ◽

M. Nastasi ◽

T. E. Mitchell ◽

...

Keyword(s):

Phase Transformation ◽

High Temperature ◽

Oxidation Resistance ◽

Elevated Temperatures ◽

Matrix Material ◽

Molybdenum Disilicide ◽

High Temperature Strength ◽

Cross Sectional ◽

Good Oxidation Resistance ◽

Structural Applications

MoSi2 is a potential matrix material for high temperature structural composites due to its high melting temperature and good oxidation resistance at elevated temperatures. The two major drawbacksfor structural applications are inadequate high temperature strength and poor low temperature ductility. The search for appropriate composite additions has been the focus of extensive investigations in recent years. The addition of SiC in a nanolayered configuration was shown to exhibit superior oxidation resistance and significant hardness increase through annealing at 500°C. One potential application of MoSi2- SiC multilayers is for high temperature coatings, where structural stability ofthe layering is of major concern. In this study, we have systematically investigated both the evolution of phases and the stability of layers by varying the heat treating conditions.Alternating layers of MoSi2 and SiC were synthesized by DC-magnetron and rf-diode sputtering respectively. Cross-sectional transmission electron microscopy (XTEM) was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures.

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WC-3015 Alloy

Alloy Digest ◽

10.31399/asm.ad.cb0021 ◽

1974 ◽

Vol 23 (5) ◽

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Physical Properties ◽

Surface Treatment ◽

Base Alloy ◽

Heat Treating ◽

Rolled Sheet ◽

Good Oxidation Resistance ◽

Structural Applications ◽

Cold Rolled

Abstract WC-3015 is a columbium-base alloy developed for structural applications in high-temperature oxidizing environments. It is characterized by good oxidation resistance, good mechanical properties and compatibility with silicide coatings. Cold-rolled sheet can be joined and welded without cracking. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-21. Producer or source: Wah Chang, a Teledyne Corporation.

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WIELAND DURO TANTALUM

Alloy Digest ◽

10.31399/asm.ad.ta0014 ◽

2020 ◽

Vol 69 (11) ◽

Keyword(s):

High Temperature ◽

Powder Metallurgy ◽

Physical Properties ◽

Tensile Properties ◽

Refractory Metal ◽

Temperature Performance

Abstract Wieland Duro Tantalum is unalloyed tantalum that is produced from powder metallurgy consolidated ingots. It is a versatile refractory metal that is used in demanding applications requiring resistance to high temperature and corrosion. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on low and high temperature performance as well as machining and joining. Filing Code: Ta-14. Producer or source: Wieland Duro GmbH.

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Recent Advances in Development and Processing of Titanium Aluminide Alloys

MRS Proceedings ◽

10.1557/proc-646-n1.1.1 ◽

2000 ◽

Vol 646 ◽

Cited By ~ 4

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.

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