The Mechanics and Mechanical Behavior of High-Temperature Intermetallic Matrix Composites

2000 ◽  
Author(s):  
Ronald Gibala ◽  
Amit K. Ghosh ◽  
David J. Srolovitz ◽  
John W. Holmes ◽  
Noboru Kikuchi
Keyword(s):  
High Temperature ◽  
Mechanical Behavior ◽  
Matrix Composites ◽  
Intermetallic Matrix ◽  
Intermetallic Matrix Composites

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.

Microstructure and Deformation of Ti-22Al-23Nb Orthorhombic-Based Monolithic and Composite Titanium Aluminides

1994 ◽  
Vol 350 ◽  
Author(s):  
François-charles dary ◽  
Shiela R. Woodard ◽  
Tresa M. Pollock
Keyword(s):  
High Temperature ◽  
Titanium Aluminides ◽  
Matrix Composites ◽  
Low Oxygen ◽  
Microstructural Stability ◽  
Two Phase ◽  
Intermetallic Matrix ◽  
Three Phase ◽  
Intermetallic Matrix Composites ◽  
Temperature Exposure

AbstractA new class of intermetallic matrix composites (IMC's) based on orthorhombic titanium aluminides offer attractive properties for high-temperature structural components at temperatures up to 760°C. Results from an ongoing study on the microstructural stability and mechanical properties of the orthorhombic-based alloy Ti-22Al–23Nb (at%), in both monolithic and composite forms, are discussed. Oxygen acquired during processing or as a result of high-temperature exposure in air or vacuum has a pronounced influence on the microstructure of the monolithic and composite materials. Two-phase lath microstructures of ordered beta (βo) + orthorhombic (O) phases produced by processing low oxygen material above the beta transus are morphologically stable at 760°C. Conversely, in higher-oxygen three-phase microstructures containing O+βo+ α2(Ti3Al), lath coarsening and additional precipitation of α2 in oxygen-enriched sheet surface regions is observed. At 760°C/69MPa the two-phase lath microstructure has a higher creep resistance and lower tensile strength compared to the three-phase α2- containing microstructures of the higher oxygen material.

Powder Metallurgy Processing of Intermetallic Matrix Composites

1994 ◽  
Vol 350 ◽  
Author(s):  
Randall M. German ◽  
Ronald G. Iacocca
Keyword(s):  
High Temperature ◽  
Powder Metallurgy ◽  
Intermetallic Compounds ◽  
Matrix Composites ◽  
Brittle Behavior ◽  
Intermetallic Matrix ◽  
Intermetallic Matrix Composites

AbstractIntermetallic compounds are similar to ceramics because they are stoichiometric, with limited compositional ranges and brittle behavior. The limited ductility forces a reliance on powder techniques for shaping and consolidation. The high temperature character of intermetallics is beneficial to high temperature service, but this same attribute contributes to difficulty in processing. This paper reviews the several powder approaches to forming intermetallic structures. Examples are given on powders, consolidation options, and properties. Densification maps are introduced for estimation of consolidation cycles. Unfortunately, many of the composites exhibit little strengthening benefit from incorporation of reinforcing phases.

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.

Microstructure of intermetallic-matrix composites produced in situ by self-propagating high-temperature synthesis

1994 ◽  
Vol 52 ◽  
pp. 708-709
Author(s):  
C. P. Doğan ◽  
D. E. Alman
Keyword(s):  
High Temperature ◽  
Exothermic Reaction ◽  
Ceramic Composites ◽  
Matrix Composites ◽  
Temperature Synthesis ◽  
Intermetallic Matrix ◽  
High Temperature Synthesis ◽  
Wide Range ◽  
Intermetallic Matrix Composites

Self-propagating, high-temperature synthesis (SHS) is one method of material production in which elemental constituents are ignited, initiating a self-sustaining, exothermic reaction that results in their transformation into intermetallic and ceramic compounds. In addition, several reactions can be initiated within a single body to form intermetallic-intermetallic, intermetallic-ceramic, or ceramic-ceramic composites in situ. The driving force for the reactions is the negative heats of mixing of the forming compounds, which results in the liberation of heat. The obvious advantages of SHS processing are that it presents an opportunity to produce near net-shape advanced materials and composites with a high level of purity in a relatively low-cost and energy efficient manner.At the U.S. Bureau of Mines, we are actively involved in the SHS processing of a wide range of singlephase intermetallic and intermetallic-matrix composites: TiAl, TiAl+TiB2, TiAl+TiC, TiAl+Ti5Si3, MoSi2+SiC. One key element of our study is a thorough understanding of the effect of processing variables, such as composition, temperature, pressure, time, powder morphology, etc., on the microstructure, and hence the properties, of these materials.

scholarly journals Comparison of NDE Results and Correlation With Microstructural Characteristics of NiFeAl/Wf

1994 ◽  
Author(s):  
David K. Hsu ◽  
Peter K. Liaw ◽  
George Y. Baaklini
Keyword(s):  
Quality Assurance ◽  
Nondestructive Evaluation ◽  
Metal Matrix ◽  
Complex Structure ◽  
Matrix Composites ◽  
Fiber Density ◽  
Microstructural Characteristics ◽  
X Ray ◽  
Intermetallic Matrix ◽  
Intermetallic Matrix Composites

Metal matrix composites (MMC) and intermetallic matrix composites (IMC) are materials of complex structure. Nominally defect-free, as-manufactured MMC requires nondestructive evaluation (NDE) for quality assurance and process monitoring purposes. In this work, three NDE techniques — ultrasonics, eddy current, and X-ray radiography — were applied to un-damaged NiFeAI/Wf coupons. Images of the coupons were obtained using the three techniques. The NDE results were compared among themselves, and correlations were sought between these results and microstructural features of the specimen. Consistencies were found among the NDE results and a strong correlation was found between the spatial variation of fiber density and the NDE signals.

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