Static Stress Concentrations due to Broken Fibres in Strain Hardenable Metal Matrix Composites Containing Elastic Fibres with Different Diameters / Statische Spannungskonzentrationen durch Faserbrüche in Verbundwerkstoffen mit einer verfestigungsfähigen Metallmatrix und elastischen Fasern unterschiedlichen Durchmessers

1988 ◽  
Vol 79 (9) ◽  
pp. 610-615
Author(s):  
Shojiro Ochiai ◽  
Kozo Osamura
Keyword(s):  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Static Stress ◽  
Matrix Composites ◽  
Elastic Fibres ◽  
Stress Concentrations ◽  
Different Diameters

Interfacial Stress Singularities at Free Edge of Hybrid Metal Matrix Composites

1988 ◽  
Vol 110 (1) ◽  
pp. 41-47 ◽  
Author(s):  
C. W. Lau ◽  
F. Delale
Keyword(s):  
Metal Matrix Composites ◽  
Plastic Flow ◽  
Metal Matrix ◽  
Stress Singularity ◽  
Local Stress ◽  
Free Edge ◽  
Interfacial Stress ◽  
Matrix Composites ◽  
Stress Concentrations ◽  
Hybrid Metal Matrix Composites

Novel hybrid-matrix composites with alternating metallic matrices of different plastic flow resistance offer excellent potential for a superior strength and toughness combination than traditional monomatrix composites. The local stress concentrations in this class of composites can be controlled by proper tailoring of the metal matrices. The free edge accentuated stress state which govern inter-matrix interfacial cracking in such hybrid metal matrix composites has been solved. Determined through asymptotic expansion and numerical methods, the local decohesion stress, σθθ, is found to be always positive for far field tensile loading. The power of the stress singularity is found to depend on the ratio of the plastic resistances of the two matrix metals. A larger difference in resistance to onset of plastic flow between the two matrix metals leads to stronger stress singularity. The work hardening behavior of the matrices also affects the power of the stress singularity. At the limit, the interfacial stress becomes nonsingular for non-workhardening matrices. Detailed results of both the power of the stress singularity, and its angular variation have been determined for a range of matrix combinations.

Electron Microscopy of Metal-Matrix Composites

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.

TEM examination of 2014-SiC metal matrix composite

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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