Silicides and Silicide Matrix Composites for High-Temperature Structural Applications

2020 ◽  
pp. 1167-1220
Author(s):  
R. Mitra
Keyword(s):  
High Temperature ◽  
Matrix Composites ◽  
Structural Applications

Survey of Eutectic Systems as Potential Intermetallic Matrix Composites for High Temperature Application

1990 ◽  
Vol 194 ◽  
Author(s):  
S. Mazdiyasni ◽  
D. B. Miracle
Keyword(s):  
High Temperature ◽  
Matrix Composites ◽  
Intermetallic Matrix ◽  
Structural Applications ◽  
Intermetallic Matrix Composite ◽  
Fracture Appearance ◽  
Temperature Application ◽  
Eutectic Systems ◽  
Temperature Damage ◽  
Intermetallic Matrix Composites

AbstractThe lack of low-temperature damage tolerance along with the desire to achieve lower densities and higher creep strengths over monolithic intermetallic materials, has sparked significant interest in the research community for the development of an intermetallic matrix composite suitable for high temperature structural applications. Eutectic systems are desirable as composites due to the inherent thermodynamic stability between matrix and reinforcement. It also allows the opportunity of controlling the microstructure by control of solidification conditions. This paper presents a qualitative examination of the toughness behavior of the Cr-Cr2Zr, Cr-Cr2Hf, Cr-Cr2Ta, Cr-Cr3Si, Ta-Cr2Ta, and Ta-Ta5Si eutectics. The evaluation is based on microcracking from microhardness indentations and fracture appearance. Relative oxidation resistance at 800°C and 1200°C is also presented.

Analysis of Heat Generation during Fracture in Ceramic Matrix Composites

2008 ◽  
Vol 385-387 ◽  
pp. 689-692 ◽  
Author(s):  
Jeong Guk Kim
Keyword(s):  
High Temperature ◽  
Heat Generation ◽  
Damage Evolution ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
In Situ Monitoring ◽  
Potential Candidate ◽  
Matrix Composites ◽  
Ir Camera ◽  
Structural Applications

Ceramic matrix composites (CMCs) have evolved as potential candidate materials for high-temperature structural applications due to lightweight, high-temperature strength and excellent corrosion and wear resistance. In this investigation, damage evolution and heat generation of CMCs during monotonic loadings were investigated using different types of nondestructive evaluation (NDE) techniques, such as acoustic emission (AE) and infrared (IR) thermography and microstructural characterization. IR camera was used for in-situ monitoring of temperature evolution, and the temperature changes during testing were measured. A significant temperature increase has been observed at the time of failure. Microstructural characterizations using scanning electron microscopy (SEM) were performed to investigate fracture behavior of CMC samples. In this investigation, the NDE technique and SEM characterization were employed to analyze damage evolution and progress of ceramic matrix composites during monotonic loading.

Lattice Imaging of Grain Boundaries in Ceramics

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.

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

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.

Microstructural characterization of plasma-processed Ti-Al metal matrix composites

1989 ◽  
Vol 47 ◽  
pp. 552-553
Author(s):  
M. G. Burke ◽  
M. N. Gungor ◽  
M. A. Burke
Keyword(s):  
High Temperature ◽  
Titanium Aluminide ◽  
Plasma Processing ◽  
Microstructural Characterization ◽  
High Temperature Strength ◽  
Matrix Composites ◽  
Intermetallic Matrix ◽  
Long Time ◽  
Strength And Stiffness ◽  
Intermetallic Matrix Composites

Intermetallic matrix composites are candidates for ultrahigh temperature service when light weight and high temperature strength and stiffness are required. Recent efforts to produce intermetallic matrix composites have focused on the titanium aluminide (TiAl) system with various ceramic reinforcements. In order to optimize the composition and processing of these composites it is necessary to evaluate the range of structures that can be produced in these materials and to identify the characteristics of the optimum structures. Normally, TiAl materials are difficult to process and, thus, examination of a suitable range of structures would not be feasible. However, plasma processing offers a novel method for producing composites from difficult to process component materials. By melting one or more of the component materials in a plasma and controlling deposition onto a cooled substrate, a range of structures can be produced and the method is highly suited to examining experimental composite systems. Moreover, because plasma processing involves rapid melting and very rapid cooling can be induced in the deposited composite, it is expected that processing method can avoid some of the problems, such as interfacial degradation, that are associated with the relatively long time, high temperature exposures that are induced by conventional processing methods.

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

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.

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

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.

WC-3015 Alloy

Alloy Digest ◽  
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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