Advanced Aerospace Materials: Titanium Aluminide Intermetallic Compounds and Metal Matrix Composites

The demand of today’s and future spacecrafts for a stable platform for critical payloads is the driving force behind the coefficient of thermal expansion (CTE) measurement of different aerospace materials. The CTE of a composite is different from that given by a simple rule of mixtures. This is because of the presence of reinforcement. The expansion coefficient of reinforcement is less than that of the matrix which introduces a mechanical constraint on the matrix. The degree of constraint is also dependent on the nature of the reinforcement. It is important to point out that interface can exert some influence on the value of CTE, especially for very small particle size. In addition to the interface, the CTE of particle reinforced metal matrix composites (MMCs) is affected by several other factors. To cater the needs of various requirements in a spacecraft making, a wide variety of materials are used. Besides, the indigenization efforts and development of new materials for space-use emphasizes the measurement of CTE before their actual use. Stir casting technique was used to fabricate composites containing Si Cp as reinforcements and special thermo physical properties of the material are found. CTE of the composites are measured by TMA. The experiments have been carried out in the temperature range -1400 C to 5750 C.

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Electron Microscopy of Metal-Matrix Composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069016 ◽

1970 ◽

Vol 28 ◽

pp. 404-405

Author(s):

A. Lawley ◽

M. R. Pinnel ◽

A. Pattnaik

Keyword(s):

Electron Microscopy ◽

Metal Matrix Composites ◽

Metal Matrix ◽

Critical Evaluation ◽

Elastic Behavior ◽

Matrix Composites ◽

Directionally Solidified ◽

Fracture Characteristics ◽

Broad Program

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.

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TEM examination of 2014-SiC metal matrix composite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105692 ◽

1988 ◽

Vol 46 ◽

pp. 726-727

Author(s):

M. G. Burke ◽

M. N. Gungor ◽

P. K. Liaw

Keyword(s):

Metal Matrix Composite ◽

Metal Matrix Composites ◽

Matrix Composite ◽

Metal Matrix ◽

Tensile Deformation ◽

Microstructural Characterization ◽

Thin Foil ◽

Matrix Alloy ◽

Matrix Composites ◽

Ion Milling

Aluminum-based metal matrix composites offer unique combinations of high specific strength and high stiffness. The improvement in strength and stiffness is related to the particulate reinforcement and the particular matrix alloy chosen. In this way, the metal matrix composite can be tailored for specific materials applications. The microstructural characterization of metal matrix composites is thus important in the development of these materials. In this study, the structure of a p/m 2014-SiC particulate metal matrix composite has been examined after extrusion and tensile deformation.Thin-foil specimens of the 2014-20 vol.% SiCp metal matrix composite were prepared by dimpling to approximately 35 μm prior to ion-milling using a Gatan Dual Ion Mill equipped with a cold stage. These samples were then examined in a Philips 400T TEM/STEM operated at 120 kV. Two material conditions were evaluated: after extrusion (80:1); and after tensile deformation at 250°C.

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