Preparation of Electron Transparent Metal-Matrix Composites

1968 ◽  
Vol 26 ◽  
pp. 334-335 ◽  
Author(s):  
M. R. Pinnel ◽  
A. Lawley
Keyword(s):  
Stainless Steel ◽  
Load Transfer ◽  
Volume Fraction ◽  
Steel Wire ◽  
Initial Step ◽  
Interfacial Region ◽  
Matrix Composites ◽  
Specific Test ◽  
The Matrix ◽  
The One

Numerous phenomenological descriptions of the mechanical behavior of composite materials have been developed. There is now an urgent need to study and interpret deformation behavior, load transfer, and strain distribution, in terms of micromechanisms at the atomic level. One approach is to characterize dislocation substructure resulting from specific test conditions by the various techniques of transmission electron microscopy. The present paper describes a technique for the preparation of electron transparent composites of aluminum-stainless steel, such that examination of the matrix-fiber (wire), or interfacial region is possible. Dislocation substructures are currently under examination following tensile, compressive, and creep loading. The technique complements and extends the one other study in this area by Hancock.The composite examined was hot-pressed (argon atmosphere) 99.99% aluminum reinforced with 15% volume fraction stainless steel wire (0.006″ dia.).Foils were prepared so that the stainless steel wires run longitudinally in the plane of the specimen i.e. the electron beam is perpendicular to the axes of the wires. The initial step involves cutting slices ∼0.040″ in thickness on a diamond slitting wheel.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

scholarly journals Predictive Computational Model for Damage Behavior of Metal-Matrix Composites Emphasizing the Effect of Particle Size and Volume Fraction

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2143
Author(s):  
Shaimaa I. Gad ◽  
Mohamed A. Attia ◽  
Mohamed A. Hassan ◽  
Ahmed G. El-Shafei
Keyword(s):  
Finite Element ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Particulate Composites ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Zone Method ◽  
Stress Strain ◽  
The Matrix

In this paper, an integrated numerical model is proposed to investigate the effects of particulate size and volume fraction on the deformation, damage, and failure behaviors of particulate-reinforced metal matrix composites (PRMMCs). In the framework of a random microstructure-based finite element modelling, the plastic deformation and ductile cracking of the matrix are, respectively, modelled using Johnson–Cook constitutive relation and Johnson–Cook ductile fracture model. The matrix-particle interface decohesion is simulated by employing the surface-based-cohesive zone method, while the particulate fracture is manipulated by the elastic–brittle cracking model, in which the damage evolution criterion depends on the fracture energy cracking criterion. A 2D nonlinear finite element model was developed using ABAQUS/Explicit commercial program for modelling and analyzing damage mechanisms of silicon carbide reinforced aluminum matrix composites. The predicted results have shown a good agreement with the experimental data in the forms of true stress–strain curves and failure shape. Unlike the existing models, the influence of the volume fraction and size of SiC particles on the deformation, damage mechanism, failure consequences, and stress–strain curve of A359/SiC particulate composites is investigated accounting for the different possible modes of failure simultaneously.

Micromechanics Approach for the Overall Elastic Properties of Ceramic Matrix Composites Incorporating Defect Structures

2020 ◽  
Author(s):  
Rajesh S. Kumar
Keyword(s):  
Elastic Properties ◽  
Volume Fraction ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Volume Shrinkage ◽  
Matrix Composites ◽  
Defect Structures ◽  
Linear Elastic ◽  
Elastic Tensor ◽  
The Matrix

Abstract Initial mechanical behavior of Ceramic Matrix Composites (CMCs) is linear until the proportional limit. This initial behavior is characterized by linear elastic properties, which are anisotropic due to the orientation and arrangement of fibers in the matrix. The linear elastic properties are needed during various phases of analysis and design of CMC components. CMCs are typically made with ceramic unidirectional or woven fiber preforms embedded in a ceramic matrix formed via various processing routes. The matrix processing of interest in this work is that formed via Polymer Impregnation and Pyrolysis (PIP). As this process involves pyrolysis process to convert a pre-ceramic polymer into ceramic, considerable volume shrinkage occurs in the material. This volume shrinkage leads to significant defects in the final material in the forms of porosity of various size, shape, and volume fraction. These defect structures can have a significant impact on the elastic and damage response of the material. In this paper, we develop a new micromechanics modeling framework to study the effects of processing-induced defects on linear elastic response of a PIP-derived CMC. A combination of analytical and computational micromechanics approaches is used to derive the overall elastic tensor of the CMC as a function of the underlying constituents and/or defect structures. It is shown that the volume fraction and aspect ratio of porosity at various length-scales plays an important role in accurate prediction of the elastic tensor. Specifically, it is shown that the through-thickness elastic tensor components cannot be predicted accurately using the micromechanics models unless the effects of defects are considered.

scholarly journals Extraction of void fraction in metal matrix composite using morphological image processing

1994 ◽  
Vol 3 (2) ◽  
pp. 096369359400300
Author(s):  
Lun X. He ◽  
David K. Hsu ◽  
John P. Basart
Keyword(s):  
Image Processing ◽  
Void Fraction ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Matrix Material ◽  
Void Content ◽  
Matrix Composites ◽  
Cross Sectional ◽  
Morphological Image Processing ◽  
The Matrix

In continuous fiber reinforced metal matrix composites, the volume fraction of voids in the matrix material is an important parameter for material property characterization. In analyzing a cross-sectional micrograph of such a composite, the presence of fiber images and voids occurring on the perimeter of fibers complicates the determination of void content. This paper describes image processing steps using mathematical morphology for the extraction of void fraction in a composite.

Micromechanics Approach for the Overall Elastic Properties of Ceramic Matrix Composites Incorporating Defect Structures

2021 ◽  
Author(s):  
Rajesh Kumar
Keyword(s):  
Elastic Properties ◽  
Volume Fraction ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Matrix Composites ◽  
Defect Structures ◽  
Modeling Framework ◽  
Linear Elastic ◽  
Elastic Tensor ◽  
The Matrix

Abstract Initial mechanical behavior of Ceramic Matrix Composites (CMCs) is linear until the proportional limit. This initial behavior is characterized by linear elastic properties, which are anisotropic due to the orientation and arrangement of fibers in the matrix. The linear elastic properties are needed during analysis and design of CMC components. CMCs are made with ceramic unidirectional or woven fiber preforms embedded in a ceramic matrix formed via various processing routes. The matrix processing of interest in this work is the Polymer Impregnation and Pyrolysis (PIP) process. As this process involves pyrolysis to convert a pre-ceramic polymer into ceramic, considerable volume shrinkage occurs in the material. This leads to significant defects in the form of porosity of various size, shape, and volume fraction. These defect structures can have a significant impact on the elastic and damage response of the material. In this paper, we develop a new micromechanics modeling framework to study the effects of processing-induced defects on linear elastic response of a PIP-derived CMC. A combination of analytical and computational micromechanics approaches is used to derive the overall elastic tensor of the CMC as a function of the underlying constituents and/or defect structures. It is shown that the volume fraction and aspect ratio of porosity at various length-scales plays an important role in accurate prediction of the elastic tensor. Specifically, it is shown that the through-thickness elastic tensor components cannot be predicted accurately using the micromechanics models unless the effects of defects are considered.

Effect of the Matrix and Reinforcement Sizes on the Microstructure, the Physical and Mechanical Properties of Al-SiC Composites

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
M. A. Salem ◽  
I. G. El-Batanony ◽  
M. Ghanem ◽  
Mohamed Ibrahim Abd ElAal
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Volume Fraction ◽  
Physical And Mechanical Properties ◽  
Particle Sizes ◽  
Matrix Composites ◽  
Volume Fractions ◽  
The Matrix ◽  
Sic Composites ◽  
Sic Particle

Different Al-SiC metal matrix composites (MMCs) with a different matrix, reinforcement sizes, and volume fractions were fabricated using ball milling (BM) and powder metallurgy (PM) techniques. Al and Al-SiC composites with different volume fractions were milled for 120 h. Then, the Al and Al-SiC composites were pressed under 125 MPa and finally sintered at 450 °C. Moreover, microsize and combination between micro and nano sizes Al-SiC samples were prepared by the same way. The effect of the Al matrix, SiC reinforcement sizes and the SiC volume fraction on the microstructure evolution, physical and mechanical properties of the produced composites was investigated. The BM and powder metallurgy techniques followed by sintering produce fully dense Al-SiC composite samples with different matrix and reinforcement sizes. The SiC particle size was observed to have a higher effect on the thermal conductivity, electrical resistivity, and microhardness of the produced composites than that of the SiC volume fraction. The decreasing of the Al and SiC particle sizes and increasing of the SiC volume fraction deteriorate the physical properties. On the other hand, the microhardness was enhanced with the decreasing of the Al, SiC particle sizes and the increasing of the SiC volume fraction.

Reinforcement of 2124 Al Alloy with Low Micron SiC and Nano Al2O3 via Solid-State Forming

2015 ◽  
Vol 828-829 ◽  
pp. 172-178
Author(s):  
Zizo Gxowa ◽  
Sigqibo Templeton Camagu ◽  
Gonasagren Govender ◽  
Manuel Filipe Pereira
Keyword(s):  
Grain Boundaries ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Al Alloy ◽  
Matrix Composites ◽  
Intergranular Cracking ◽  
Powder Metallurgical Process ◽  
Hardness Tests ◽  
Mode Of Failure ◽  
The Matrix

A powder metallurgical process was used to fabricate Metal Matrix Composites (MMCs). A 2124 aluminium alloy was reinforced with 5 and 10 vol.% of Al2O3(40-70nm) to form Metal Matrix Nano Composites (MMNCs) as well as 10 and 15 vol.% of SiC (1-10µm) to fabricate low micron MMCs. It was observed that the nano-sized Al2O3particles were evenly dispersed in the aluminium matrix while a lot of loose SiC particles settled on the grain boundaries in the low micron MMCs. The relative density of all the composites increased due to sintering, however full densification was not achieved. This result was attributed to the hindered motion of dislocations, grains and grain boundaries by reinforcing particles. The 2124-Al/10%-SiC composite was cold extruded and the extruded part fractured. A metallographic evaluation was carried out and it was deduced that the mode of failure was intergranular cracking. Hardness tests performed after sintering indicated that hardness increased with an increase in volume fraction of reinforcement in the matrix. Annealing of the extruded part resulted in a decrease in hardness.

Mechanical Properties of Densified Untwisted Carbon Nanotube Yarn / Epoxy Composites

2015 ◽  
Author(s):  
Risa Yoshizaki ◽  
Kim Tae Sung ◽  
Atsushi Hosoi ◽  
Hiroyuki Kawada
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Polymer Matrix Composites ◽  
High Strength ◽  
Matrix Composites ◽  
Specific Strength ◽  
The Matrix ◽  
Cnt Arrays ◽  
Strength And Stiffness ◽  
Long Fibers

Carbon nanotubes (CNTs) have very high specific strength and stiffness. The excellent properties make it possible to enhance the mechanical properties of polymer matrix composites. However, it is difficult to use CNTs as the reinforcement of long fibers because of the limitation of CNT growth. In recent years, a method to spin yarns from CNT forests has developed. We have succeeded in manufacturing the unidirectional composites reinforced with the densified untwisted CNT yarns. The untwisted CNT yarns have been manufactured by drawing CNTs through a die from vertically aligned CNT arrays. In this study, the densified untwisted CNT yarns with a polymer treatment were fabricated. The tensile strength and the elastic modulus of the yarns were improved significantly by the treatment, and they were 1.9 GPa and 140 GPa, respectively. Moreover, the polymer treatment prevented the CNT yarns from swelling due to impregnation of the matrix resin. Finally, the high strength CNT yarn composites which have higher volume fraction than a conventional method were successfully fabricated.

Micromechanical theory and uniaxial tensile tests of fiber reinforced cement composites

1991 ◽  
Vol 6 (11) ◽  
pp. 2463-2473 ◽  
Author(s):  
C.C. Yang ◽  
T. Mura ◽  
S.P. Shah
Keyword(s):  
Volume Fraction ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Cement Composites ◽  
Matrix Composites ◽  
Fiber Reinforced ◽  
Theoretical Predictions ◽  
The Matrix ◽  
Reinforced Cement ◽  
Fracture Arrest

The mechanism of fracture arrest in brittle-matrix composites with strong, long fibers is analyzed by using the inclusion method. The maximum stress contribution of the matrix in composites is discussed in this paper. A critical volume fraction of fibers fc is theoretically derived. If the volume fraction f is less than fc, then debonding between fibers and matrix occurs before the crack propagates through the whole section. If f is greater than fc, then no debonding occurs before the crack propagates through the whole section. The value of fc depends on the matrix and fiber properties and the bond character of the interface. To verify the analytical predictions, experiments on fiber reinforced cement composites subjected to uniaxial tension were conducted. The results of the theoretical predictions were also compared satisfactorily with other published experimental data.

Experimental Investigation of Tensile Properties and Fracture Mechanism of WCP/Cu Composites Reinforced with Different WCP Volume Fraction

2011 ◽  
Vol 415-417 ◽  
pp. 2244-2247 ◽  
Author(s):  
Feng Yan ◽  
Rong Xin Guo ◽  
Hai Ting Xia ◽  
Hai Yu ◽  
Yu Bo Zhang
Keyword(s):  
Mechanical Properties ◽  
Fracture Behavior ◽  
Volume Fraction ◽  
Copper Matrix ◽  
Matrix Composites ◽  
Fracture Surface Morphology ◽  
Test Results ◽  
Tension Tests ◽  
Tensile Performance ◽  
The Matrix

The copper matrix composites reinforced by different WCP volume fraction were fabricated via Vacuum Hot-pressed Sintering technique. The tensile performance and fracture behavior of WCP/Cu composites were studied by uniaxial tension tests and the fracture surfaces were examined by SEM. The test results of mechanical properties show that the WCP/Cu composites exhibit obvious improvement of tensile property comparing with that of the matrix. The fracture surface morphology indicate a trend that the fracture of WCP/Cu composites changes from debonding to cleavage with the increase of the WCP volume fraction.

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