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metal-matrix-composites--mmcs
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Investigation of Toughening Mechanisms in Al/Al3Ti In-Situ Hot Extruded Composites
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
In this study in-situ Al/Al3Ti was fabricated by mechanical alloying, hot extrusion and subsequent heat treatment. First, initial pure powders of Al and Ti were mechanically alloyed with 5 weight percentages of Ti for 40 hours. The as-hot extruded samples containing 5 wt% of initial Ti particles, were exposed to heating at 600 oC for various time intervals up to 10 hours. Microstructure analysis by OM and SEM proved that in-situ Al3Ti phase was formed as a layer around Ti particles by solid reactive diffusion between Al and Ti particles. After 10 hours of heating, all the Ti particles were consumed and transformed to Al3Ti. Mechanical properties of samples were investigated by Brinell...
Production of Copper Matrix Composites Reinforced with Aluminum Oxide Particles by In-Situ (Mechanical Alloying and Internal Oxidation) and Ex-Situ Methods
, M.Sc. Thesis Sharif University of Technology ; Purazarng, Kazem (Supervisor) ; Abachi, Parvin (Supervisor)
Abstract
In this study, copper-alumina composite specimens with different reinforcement content were produced in two routes, i.e. in-situ and ex-situ; one specimen as functionally graded material (FGM) was also produced. In first method, copper and aluminum powders were initially alloyed by mechanical alloying route and then the copper oxide powder was added as oxidizer. For the fabrication of Cu-Al2O3 composites using ex-situ method, alumina nano particles powder was added to elemental copper powder. FGM specimen consists of five layers, i.e. pure copper, copper matrix composite having 2, 3, 4, and 5 volume percent alumina. To reduce the particles agglomeration and homogeneous distribution of...
Incorporating aspect ratio in a new modeling approach for strengthening of MMCs and its extension from micro to nano scale
, Article Advanced Composite Materials ; Volume 19, Issue 4 , Apr , 2010 , Pages 299-316 ; 09243046 (ISSN) ; Bagheri, R ; Zebarjad, S. M ; Razavi Hesabi, Z ; Sharif University of Technology
2010
Abstract
The strengthening behavior of particle reinforced metal-matrix composites is primarily attributed to the dislocation strengthening effect and the load transfer effect. To account for these two effects in a unified way, a new multi-scale approach is developed in this paper incorporating the aspect ratio effect into the geometrically necessary dislocation strengthening relationships. By making use of this multi-scale approach, the deformation behavior of metal-matrix composites (MMCs) and metal-matrix nanocomposites (MMNCs) as a function of size, volume fraction, aspect ratio, etc. of the particles has been investigated. Comparison with the previously proposed models and the available...
Interaction of two nearby CNTs/nanovoids embedded in a metal matrix using modified nonlocal elasticity
, Article Composites Part B: Engineering ; Volume 43, Issue 8 , December , 2012 , Pages 3167-3181 ; 13598368 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2012
Abstract
Interaction of Carbon Nanotubes (CNTs) and nanovoids embedded in a metal matrix is studied comparatively. For this purpose, two nearby CNTs/nanovoids are modeled as two similar cylindrical inclusions/holes in an infinite matrix. The nonlocal stresses around the CNTs/nanovoids are obtained by applying the integral constitutive equation of the nonlocal elasticity to the stresses from the complex stress potential method. Also, in order to bring different nonlocality effects of dissimilar media into account, the influence function of the nonlocal elasticity is modified. Effects of the CNTs/nanovoids size and distance as well as far-field loading ratio on the stress state in the matrix are...
A fem study of the overlapping ratio effect on superplastic formation of metal matrix composites
, Article 27th Congress of the International Council of the Aeronautical Sciences 2010, ICAS 2010, 19 September 2010 through 24 September 2010, Nice ; Volume 3 , 2010 , Pages 1836-1843 ; 9781617820496 (ISBN) ; Abedian, A ; Sharif University of Technology
2010
Abstract
In aerospace applications structures weight is considered as a major performance parameter. One of the most effective manufacturing methods for weight reduction is superplastic forming. By this technique, not only the weight, but also the stress concentration, the cost, and the manufacturing time are noticeably reduced. Additionally, the components with complicated shapes could be formed in a single manufacturing step. Due to the wide demand for whiskers reinforced metal matrix composites (MMCs) in aerospace industries, many research works have been designed to extend the borders of superplastic forming to MMCs materials. In the present study, a 3-D symmetric micromechanical finite element...
Shock wave sintering of Al/SiC metal matrix nano-composites: A molecular dynamics study
, Article Computational Materials Science ; Volume 125 , 2016 , Pages 255-262 ; 09270256 (ISSN) ; Mahnama, M ; Naghdabadi, R ; Sharif University of Technology
Elsevier
2016
Abstract
Mechanical properties of nano-composites produced by shock wave sintering of aluminum and silicon carbide nano-powders are investigated using Molecular Dynamics (MD) simulations. In this regard, the shock wave response of aluminum and silicon carbide nano-particles, arranged in a BCC super-lattice, is studied via the NPHug Hugoniostat method. Moreover, the effect of the initial hydrostatic compaction of powders as well as the cooling rate of the shocked material on the mechanical properties of the shock-sintered nano-composites is investigated. Employing the Hugoniot curves corresponding to the powders, it is concluded that an initial hydrostatic pressure, leads to a less temperature rise...
Hardness, wear and friction characteristics of nanostructured Cu-SiC nanocomposites fabricated by powder metallurgy route
, Article Materials Today Communications ; Volume 18 , 2019 , Pages 25-31 ; 23524928 (ISSN) ; Najafi, M ; Alipour, S ; Kim, H.S ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In the present study, hardness and tribological properties of nanostructured copper reinforced with SiC nanoparticles of various volume fractions (0, 2, 4, and 6 vol%) were investigated. The nanocomposites were fabricated by high-energy mechanical milling and hot pressing method. The Cu-SiC nanocomposites showed enhanced hardness and wear resistance against WC counterface. The hardness and wear resistance of the nanocomposite increased with increasing the amount of SiC nanoparticles up to 2 vol% in the matrix, but they decreased at higher percentages of SiC (4 and 6 vol%). Flake formation-spalling and abrasion were identified as the predominant wear mechanisms. It was found that reducing the...
Production of high strength Al-Al 2O 3 composite by accumulative roll bonding
, Article Composites Part A: Applied Science and Manufacturing ; Volume 43, Issue 2 , February , 2012 , Pages 261-267 ; 1359835X (ISSN) ; Akbarzadeh, A ; Owhadi, A ; Sharif University of Technology
Abstract
Recently accumulative roll bonding has been used as a novel method to produce particle reinforced metal matrix composites. In this study, aluminum matrix composite reinforced by submicron particulate alumina was successfully produced and the effects of number of ARB cycles and the amount of alumina content on the microstructure and mechanical properties of composites were investigated. According to the results of tensile tests, it is shown that the yield and tensile strengths of the composite are increased with the number of ARB cycles. Scanning electron microscopy (SEM) reveals that particles have a random and uniform distribution in the matrix by the ARB cycles and a strong mechanical...