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Friction stir welding of a P/M Al–Al2O3 nanocomposite: Microstructure and mechanical properties
, Article Materials Science and Engineering: A (Elsevier) ; 2014, 585, 222-232 ; Sharif University Of Technology
Abstract
Solid-state joining of powder-metallurgy processed (P/M) Al–2 vol% Al2O3 (15 nm) nanocomposite by friction stir welding (FSW) was studied. The nanocomposite was prepared via high-energy mechanical milling followed by hot consolidation processes. The microstructure, mechanical properties and fracture behavior of the welds were evaluated and compared with FSWed wrought 1050 aluminum sheets (WAS). We have found that unlike WAS that can processed at various FSW conditions, the working window for the solid-state joining of P/M nanocomposite is narrow and only feasible at relatively high heating inputs. Microstructural studies showed the formation of melted zones with high hardness at the...
Ultrasonic Assisted Machining of Metal Matrix Composites
,
M.Sc. Thesis
Sharif University of Technology
;
Movahhedy, Mohammad Reza
(Supervisor)
;
Akbari, Javad
(Supervisor)
Abstract
In metal matrix composites, the metal is reinforced with ceramic particles to get appropriate properties for hardness, resistance to fatigue, wear resistance and strength. Aluminum matrix composites have lower density than steels. These kinds of materials are used in military, automotive and aerospace industries due to their high strength to weight ratio and resistance to corrosion and wear. Application development of these materials are limited due to high machining and production costs. High ductility and strength of these materials and also hardness of ceramic particles cause rapid wear of tools and higher roughness of the surface. In this project the effect of ultrasonic vibration of a...
Analysis and Optimization of Ultrasonic-Assisted Milling of Metal Matrix Composites (MMCs)
, M.Sc. Thesis Sharif University of Technology ; Movahedi, Mohammadreza (Supervisor) ; Fallah, Famida (Supervisor)
Abstract
Machining of Aluminum Metal Matrix Composites faces different problems including adhesive wear, large machining forces, chatter, poor surface quality and therefore low geometric accuracy etc. due to the fact that a ductile matrix is supporting brittle particles. On of the methods used to reduce such difficulties is vibration assisted machining in which a 10 to 20 micron displacement stimulation is applied to the workpiece or tool during machining process. The effect of this method on the milling of the Al/Sic composite is studied through two separate experiments including one and two dimentional vibration assisted milling respectively. Milling forces, tool wear and surface quality are...
Investigation of Mechanical Properties of Particulate Metal Matrix Nanocomposites Using Surface Elasticity Theory
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Asghari, Mohsen (Supervisor)
Abstract
Excellent mechanical properties and high aspect ratio of carbon nanotubes have been the reason for extensive research on nanocomposites reinforced by this nanostructure, and recently metal matrix type of these nanocomposites, due to their advantages, have received great attention. Moreover, nanoporous materials are another type of nanostructured materials which due to their very high porosity have special applications in hydrogen storage, separating molecules, purification and energy absorption. Because of completely neglecting the details of nanoscale structure and not paying attention to the length scale, classical continuum mechanics methods are not precise enough for evaluating different...
Fabrication of Al /Al3Ti in-situ Composite by Mechanical Alloying and Two-Step Hot Press
, M.Sc. Thesis Sharif University of Technology ; Maddah Hosseini, Hamid Reza (Supervisor)
Abstract
Al /Al3Ti in-situ composite have been fabricated by mechanical alloying and two-step hot pressing of powders containing Al and 20%wt Ti. Samples were characterized by using optical microscopy, density measurement, brinel hardness, XRD analysis. An increasing density was observed with increasing pressure until certain pressure and after that the density of composite decreased, which can be attributed to the increase in the level of porosity level and the amount of forming Al3Ti. The samples that hot pressed under cycle 5 and 6, showed the most volume fraction of in-situ phases on the matrix. The wear behavior of Al based composites reinforced with in situ Al3Ti particles has been investigated...
Control of Formation, Dispersion and Morphology of TiB2 Particles in Al-TiB2 Metal Matrix In-Situ Composite through Optimization of Melt Condition
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor) ; Davami, Parviz (Co-Advisor)
Abstract
A study has been carried out on the formation of TiB2 particles in an aluminum based in-situ metal matrix composite by mixing master alloys containing Ti and B i.e., Al-10Ti and Al-8B with a Ti:B weight ratio of 5:2. It was shown that the microstructure of the composite was greatly affected by the controlling factors of the in-situ reaction like temperature, reaction time and stirring of the melt. An increasing reaction time leads to the dissolusion of the primary phases (AlB2 and Al3Ti) and the increase in TiB2 volume fraction. Optical microscope and SEM images were used to study these changes and XRD analysis was applied to confirm these observations. The act of melt stirring in short...
Investigation the Machinability of Al/SiC Composite
, M.Sc. Thesis Sharif University of Technology ; Kouchakzade, Mohammad Ali (Supervisor) ; Yoosafi, Reza (Supervisor)
Abstract
Metal matrix composites (MMCs) have received considerable attention due to their excellent engineering properties, but their poor machinability has been the main deterrent to their substitution for metal parts. The hardness and abrasive nature of reinforcement phase causes rapid tool wear during machining and, consequently, high machining costs. This paper discusses an experimental investigation on the machinability of Al-SiC particulate metal matrix composite produced by powder metallurgical process with , and %SiC. Continuous dry turning of round composite bars using titanium carbide inserts has been selected as the test method. The influence of machining parameters, e.g. cutting speed,...
Sintering of Metal Matrix Nanocomposites Under Shock Wave by Coarse Grained Molecular Dynamics
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Mahnama, Maryam ($item.subfieldsMap.e)
Abstract
Nowadays, metal matrix composites due to their magnificent properties, has met diverse applications in automobile, aerospace and military industries. Decreasing the reinforcement size from micro-meter to nano-meter, properties of these structures will be improved significantly. Better properties will lead to better applications for them in the future. Thus, the main objective of the current project was investigation on the mechanical properties of metal matrix nanocomposites produced with shock wave sintering. In order to gain this aim, first the sintering of nanoparticles was modeled. A new model was proposed to consider the neighboring particles effects. Using the model, sintering of many...
Using ARB Process for Metal Matrix Foam and Composite Production
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Metal matrix composites (MMC) and metal foams (MF) have been the topic of numerous researches during the last decades. The appropriate mechanical and physical properties of these materials make them useful in various industries. In this research, a unique approach is introduced for producing MMCs and MFs in which accumulative roll bonding (ARB) is employed in order to achieve a homogeneous distribution of ceramic particles in the metal matrix. Also, foamed structures can be made by subjecting Al/TiH2 composite to an appropriate annealing heat treatment where TiH2 particles decompose to hydrogen and titanium. In this work, the effect of number of ARB cycles on the size and distribution of...
Study on Hot Extrusion of AA2017-10%SiCp
, M.Sc. Thesis Sharif University of Technology ; Serajzade, Siamak (Supervisor)
Abstract
In this study, hot extrusion of AA2017-10%SiC¬p composite during deformation process and effect of deformation parameters on mechanical properties have been investigated. At the first step, hot compression tests have been carried out to obtain the flow behavior of the material at different temperatures and strain rates. The activation energy of hot deformation was calculated 296 Kj/mol. In the next step, by using a finite element model in ABAQUS software and the results of uniaxial hot compression test behavior of AA2017 and AA2017-10%SiC¬p during hot and warm extrusion have been investigated. By using it temperature gradient and velocity field and strain distribution were predicted. In the...
Design, Fabrication and Characterization of Lead-Free Nano-Composite Solder Sn-Ag-Cu/ CeO2
, Ph.D. Dissertation Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
As one of the key technologies for high performance electronic devices, composite solders have been recently developed to improve thermal and mechanical properties of solder joints. In this study, accumulative roll bonding (ARB) process was used as an effective alternative method for manufacturing high-strength, finely dispersed, void-free and highly uniform Sn-Ag-Cu/CeO2 nanocomposite solders. Microstructural investigation of nanocomposite solders revealed that homogenous distribution of CeO2 nanoparticle has been achieved and the eutectic as-cast morphology of the solder changed to recrystallized fine grained structure. As a result of severe plastic deformation during rolling, brittle and...
Studying the Effect of Thermal Loading on Delamination Phenomenon of Composite Materials using Continuum Damage Mechanics
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
Metal and inter-metallic matrix composites offer high performance materials suitable for many low weight applications which are of growing interest in high tech industries. However, to submit their entire potential applications, their complex mechanical behavior has to be understood. Nevertheless, one of the major setbacks of designing with these materials has been the delamination phenomenon. So far, this phenomenon has been considered from macro-mechanical point of view regarding laminates to be semi-isotropic or orthotropic; which indicates the importance of micro-mechanical research to be done. Furthermore, the fact that macroscopic response and failure mechanisms of these composites are...
Fabrication of AZ91/ SiCp Composite In Semi-Solid State By Using Electromagnetic Stirring, Microstructures And Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Aashuri, Hossein (Supervisor)
Abstract
In this study AZ91 alloy reinforced by SiC particles processed by semi-solid casting was produced by using electromagnetic stirrer. In order to prevent ignition and oxidation of the melted AZ91 alloy 1 Wt.% of calcium was added to the melt. In order to surface oxidation of SiC particles, they were heat treated in 1100 ᵒC for 2 hours before adding to the melt. Different methods of adding SiC particles to the melt were investigated. Particle distribution in the matrix was studied qualitatively and quantitatively using microscopic images and image analysis, respectively. It is shown that higher amount of reinforcement particle need to be added to the melt in multi-steps. Frequency versus...
Microstructure Optimization of In-situ Al-Al3Ti Nanocomposite Fabricated by Mechanical Alloying & Hot Extrusion for Improving the Fracture Toughness
, Ph.D. Dissertation Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor) ; Seyyed Reihani, Morteza (Supervisor)
Abstract
The aim of this research was to fabricate an in-situ Al-Al3Ti nanocomposite from pure microsized aluminum and titanium powders by mechanical alloying and hot extrusion without any usage of nanometric particles or applying secondary heat treatments. The focus of the present research was fabricating a nanocomposite material with high strength, modulus and hardness accompanied with high fracture toughness that could be comparable with aluminum alloys in terms of fracture toughness. Mechanical alloying and hot extrusion techniques were employed to produce in-situ fully dense Al-Ti composites. Platenary and high energy vibratiory mill was used to produce composites with different percent of...
Investigation of Chip Formation Theories in Machining of Al/SiCp Metal Matrix Composite
, M.Sc. Thesis Sharif University of Technology ; Koochakzadeh, Mohammad Ali (Supervisor) ; Yousefi, Reza (Supervisor)
Abstract
Prediction of shear plane angle is a way for prediction of the mechanism of chip formation, machining forces and so on. In this study, Merchant, Corrected Merchant, Lee and Shaffer, Lee and Shaffer with Built up Edge, Corrected Lee and Shaffer and Slip line theories are used for prediction of shear plane angles and cutting forces in machining of Al/SiCp metal matrix composite. The experimental cutting forces are compared with the calculated cutting force based on shear plane angles extracted from Merchant, Corrected Merchant, Lee and Shaffer, Lee and Shaffer with Built up Edge, Corrected Lee and Shaffer and Slip line theories. The variation of these cutting forces with cutting speed, feed...
FEM Analysis of the Effects of Geometric Parameters on the Superplastic Forming of Metal Matrix Composit
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
In aerospace applications, the weight of structures is considered as a major performance parameter. One of the most effective ways for weight reduction is then attributed to the structurally continuous manufacturing of mechanical components. In this way, not only the weight, but also the stress concentration, the cost, joints and fasteners applications, and the time of manufacturing are noticeably reduced. With this method, components with complicated shapes could be formed in a single manufacturing step. Special specification of whisker reinforced Metal Matrix Composites (MMC’s) has made these materials very attractive for the aerospace applications.That is why the superplastic forming of...
Elastic-Plastic Behavior Analysis of Short Fiber Metal Matrix Composites under Thermal Loading
, Ph.D. Dissertation Sharif University of Technology ; Abedian, Ali (Supervisor) ; Mondali, Mahdi (Supervisor)
Abstract
The use of metal matrix composite materials (MMC) in aerospace structures and engine parts has become more frequent recently. These materials are composed of metal matrices reinforced by hard discontinuous ceramic fibers, usually oriented longitudinally within the matrix, and due to the stability of the mechanical properties, including the hardness and the strength at high working temperatures, have found various applications.Stress transfer from the matrix to the fiber is known as the most important mechanism governing the deformation and the fracture response of such MMCs. The stress transfer characteristic of fiber reinforced composite materials under various mechanical and thermal...
Multi-scale Modeling to Obtain an Equivalent Homogeneous Material for Al6061-T6/Al2 O3 Composite and its Application in Machining Simulation
, Ph.D. Dissertation Sharif University of Technology ; Movahedy, Mohammad Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Mahnama, Maryam ($item.subfieldsMap.e)
Abstract
In this study, an equivalent homogenous material model is proposed for Al6061-T6/Al2O3 metal matrix composite using the hierarchical multi-scale modeling, and the capability of this model in simulation of machining process of this composite is investigated. Molecular dynamic study of the Al/Al2O3 interface is used to obtain the effect of crystallographic orientations and terminations on the tensile and shear strengths at the interface. The Reaxff potential function is employed to estimate the traction-separation relations at Al/Al_2 O_3 interface at temperatures of 300, 400, and 500 K. Next, a cohesive zone model is used at the micro-scale to simulate the interface between the matrix and...
Using FSP Method to Create Composite and Surface Foam with Distribution Gradient of Particles and Porosity as FGM and Study of Physical and Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Nowadays, the tendency to use Al/SiC composites with FGM structure has increased in the automotive and aerospace industries, because in this type of composite, the properties can be gradually changed in the direction of thickness. For example, one composite surface is used as a wear-resistant or high-temperature-resistant coating, and the other surface can be welded, has high thermal conductivity, or has a good toughness. In recent years, methods have been used to make surface composites, most of which are in the molten state and at high temperatures. In this case, the reactions between the compounds can not be easily controlled and the possibility of the formation of undesirable or...
Experimental Study and Optimization of Laser Assisted Machining of Particle Reinforced Aluminum Matrix Composite
, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza (Supervisor) ; Khodaygan, Saeed (Co-Supervisor)
Abstract
In this thesis, the process of laser assisted machining (LAM) of metal matrix composites (MMC) is experimentally studied. The effects of process parameters (cutting speed, feed rate and depth of cut), laser parameters (laser power, laser frequency and laser beam angle), and the percentage of reinforcing particles on the tool wear and the surface roughness are investigated. Furthermore, the effects of these parameters on the built-up edge (BUE), chip shape, and workpiece temperature are explored.The experiments were performed using uncoated tungsten carbide and PCD tools under dry conditions. In order to analyze the sensitivity of the process parameters, the Plackett-Burman method was used...