Search for: aluminum-alloys
Total 296 records
Development of fcc-Al nanoparticles during crystallization of amorphous Al–Ni alloys containing mischmetal: Microstructure and hardness evaluation [electronic resource], Article Materials Science and Engineering A ; Volume 604, 16 May 2014, Pages 92-97 ; Simchi, A ; Varahram, N ; Park, E. S ; Sharif University of Technology
In the present work, fcc-Al nanoparticle development in Al90−xNi10MMx (MM: Ce mischmetal; x=2, 4) amorphous alloys was studied via non-isothermal differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, and nanoindentation test. Results showed that the crystallization of Al88Ni10MM2 alloy occurred by the precipitation of fcc-Al nanoparticles followed by the crystallization of Al11MM3 and Al3Ni phases. Transmission electron microscopy revealed that the aluminum precipitates had an average size of ~12 nm with a round morphology. Increasing the mischmetal content to 4 at% (Al86Ni10MM4 alloy) caused a three-stage crystallization process with a change in the size...
Evaluation of simultaneous effect of melt filtration and cooling rate on tensile properties of A356 cast alloy, Article Iranian Journal of Materials Science and Engineering ; Volume 16, Issue 3 , 2019 , Pages 44-51 ; 17350808 (ISSN) ; Davami, P ; Pirmohammadi, M ; Sharif University of Technology
Iran University of Science and Technology 2019
B The combined influence of both melt filtration and cooling rate on the microstructure and mechanical properties of A356 cast alloy was studied. A step casting model with five different thicknesses was used to obtain different cooling rates. The effect of melt filtration was studied by using 10 and 20 pores per inch (PPI) ceramic foam filters in the runner. Results showed that secondary dendrite arm spacing decreased from 80 μm to 34 μm with increasing cooling rate. Use of ceramic foam filters in the runner led to the reduction of melt velocity and surface turbulence, which prevented the incorporation of oxide films and air in the melt and consequently had an overall beneficial effect on...
Article Journal of Materials Processing Technology ; Volume 147, Issue 2 , 2004 , Pages 185-190 ; 09240136 (ISSN) ; Mohammadi, R ; Sepehrband, P ; Sharif University of Technology
Tearing energy of AA5010 aluminum alloy sheets has been studied by the single tensile testing (STT) and multiple tensile testing (MTT) methods. The total energy required to tear the specimens was assumed to be composed of two components; one associated with uniform plastic deformation, which occurs in the work-hardening range of the material, and the other with post-uniform deformation and tearing which leads to the failure of the specimens. In the STT method, tearing energy was calculated by subtracting the plastic deformation energy, dissipated in the uniform deformation range, from the total energy absorbed by a single specimen during tension. In the MTT method, which uses different...
Article Scientia Iranica ; Volume 11, Issue 4 , 2004 , Pages 392-397 ; 10263098 (ISSN) ; Seyed Reihani, S. M ; Sharif University of Technology
Sharif University of Technology 2004
In this work, the production and properties of Al 6061/SiC composites, made using a squeeze casting method, were investigated. SiC preforms were manufactured by mixing SiC powder, having a 16 and 22 pm particle size, with colloidal silica as a binder. 6061 Al melt was squeeze cast into the pores of the SiC preform to manufacture a DRA composite containing 30v/o reinforcement. The aging behavior, tensile properties and fracture mechanism of the cast material were studied. The results show that higher hardness, yield strength, tensile strength and Young's modulus can be obtained by the addition of SiC particles to 6061 Al alloy, whereas tensile elongation decreases. This is mainly caused by a...
Non-isothermal kinetic studies of crystallization in amorphous Al86Ni10MM4 alloy [electronic resource], Article Journal of Non-Crystalline Solids ; 1 March 2014, Volume 387, Pages 36–40 ; Simchi, A. (Abdolreza) ; Lee, J. I ; Park, E. S ; Varahram, N ; Sharif University of Technology
Al86Ni10MM4 (MM: Mischmetal) amorphous ribbons were prepared by melt spinning on a child copper wheel. Non-isothermal crystallization kinetics of the amorphous alloy was studied by differential scanning calorimetry (DSC). The crystallized phases were determined by X-ray diffraction method and transmission electron microscopy. DSC traces were analyzed by Kissinger method to determine the apparent activation energy of crystallization. Changes in the activation energy (Eα) with progression of crystallization were also evaluated by differential iso-conversional method of Friedman. For the precipitation of nanometer-sized Al particles, the activation energy slightly increased with increasing the...
Microstructural features, texture and strengthening mechanisms of nanostructured Al6063 alloy processed by powder metallurgy [electronic resource], Article Journal of Materials Science and Engineering: A ; 15 May 2011, Volume 528, Issue 12, Pages 3981–3989 ; Simchi, A. (Abdolreza) ; Kim, H. S ; Sharif University of Technology
Nanostructured AA6063 (NS-Al) powder with an average grain size of ∼100 nm was synthesized by high-energy attrition milling of gas-atomized AA6063 powder followed by hot extrusion. The microstructural features of the consolidated specimen were studied by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques and compared with those of coarse-grained AA6063 (CG-Al) produced by hot powder extrusion of gas-atomized powder (without using mechanical milling). The consolidated NS-Al alloy consisted of elongated ultrafine grains (aspect ratio of ∼2.9) and equiaxed nanostructured grains. A high fraction (∼78%) of high-angle grain boundaries with average...
Effect of multi-pass friction stir processing on the microstructure, mechanical and wear properties of AA5083/ZrO2 nanocomposites, Article Journal of Alloys and Compounds ; Volume 726 , 2017 , Pages 1262-1273 ; 09258388 (ISSN) ; Alipour, M ; Hamouda, A. M. S ; Matin, A ; Kord, S ; Afshari, B. M ; Koppad, P. G ; Sharif University of Technology
In this study, multi-pass friction stir processing using zirconia nanoparticles was performed on AA5083 sheets to fabricate surface nanocomposites. Effect of using different number of passes on the microstructure, microhardness, tensile and wear properties of the specimens was investigated. Therefore, it was found that iteration of FSP consistently improves tensile properties and microhardness of the materials. This was mainly related to microstructural modification through FSP, including better dispersion of powders, finer grain size and minimum clustered particles. EBSD and TEM analysis indicated a large number of high angle grain boundaries and occurrence of continuous dynamic...
Article Materials Science and Engineering A ; Volume 335, Issue 1-2 , 2002 , Pages 186-190 ; 09215093 (ISSN) ; Kokabi, A. H ; Sharif University of Technology
An approach for calculating weld efficiency from the results of a peel test has been developed for 5754-aluminum strips. The method is based on estimating the effective load-bearing area of peel test specimens. A convincing agreement between the results and the theoretical model-earlier developed by Wright et al. (Metals Technol. 5 (1978) 24)-has been found. The influence of surface expansion and rolling pressure on the weld efficiency has been studied by the new approach. © 2002 Elsevier Science B.V. All rights reserved
Simulation and experimental analyses of dynamic strain aging of a supersaturated age hardenable aluminum alloy, Article Materials Science and Engineering A ; Volume 585 , 2013 , Pages 165-173 ; 09215093 (ISSN) ; Karimi Taheri, A ; Kim, H. S ; Sharif University of Technology
In this paper, dynamic strain aging (DSA) behavior in a temperature range of (25-235°C) and strain rate range of (10-4-5×10-2s-1) was investigated using a supersaturated age hardenable aluminum alloy. It was found that two mechanisms consisted of pinning of solute atoms to mobile dislocations and dynamic precipitation, were responsible for DSA in the testing conditions. The effects of both mechanisms on the macroscopic flow curve were studied using experimental and improved physically based material modeling approaches. It was shown that both phenomena lead to a negative strain rate hardening in the alloy. Dynamic precipitation acting at high temperature results in considerable work...
Investigation of structural and mechanical properties of magnetic pulse welded dissimilar aluminum alloys, Article Journal of Manufacturing Processes ; Volume 37 , 2019 , Pages 292-304 ; 15266125 (ISSN) ; Abdollah zadeh, A ; Sarvari, M ; Pouranvari, M ; Miresmaeili, R ; Sharif University of Technology
Elsevier Ltd 2019
The present study aimed to join AA4014 to AA7075 by using magnetic pulse welding (MPW). In addition, acceptable joints were achieved by selecting welding parameters such as collision angle and discharge energy appropriately. Changing collision angle and discharge energy can influence the velocity, leading to the formation of three different types of welding interfaces with wavy, molten wavy and porous morphologies. The formation of these various morphologies is mainly associated with different collision angle parameters. The hardness of the welding interface with molten layer was significantly higher than that of the base metals due to the grain refinement phenomenon occurring through the...
Viscosity estimation of semi-solid alloys by drop weight backward extrusion test under high speed deformation, Article Semi-Solid Processing of Alloys and Composites 10 - Selected, peer reviewed papers from the 10th International Conference on Semi-Solid Processing of Alloy and Composites, S2P 2008, Aachen, 16 September 2008 through 18 September 2008 ; Volume 141-143 , 2008 , Pages 379-384 ; 10120394 (ISSN); 9771012039401 (ISBN) ; Aashuri, H ; Khosravani, A ; Foroughi, A ; Sharif University of Technology
Trans Tech Publications Ltd 2008
A simple method for estimating the apparent viscosity of semi-solid alloys was investigated. A drop weight of 50Kg and backward extrusion equipments were used to test the deformation. Backward extrusion was employed in a closed die system due to the very little separation of liquid from solid phases compared with other methods at very high deformation rate. The half of the calculated impact velocity, 700mm/s was considered as an average velocity for deformation during the test, since the slop of the velocity changes against time is constant in the middle stage of the deformation. The initial height of the sample and the thickness of the residual compressed solid at the bottom of the cup were...
Article Semi-Solid Processing of Alloys and Composites 10 - Selected, peer reviewed papers from the 10th International Conference on Semi-Solid Processing of Alloy and Composites, S2P 2008, Aachen, 16 September 2008 through 18 September 2008 ; Volume 141-143 , 2008 , Pages 605-610 ; 10120394 (ISSN); 9771012039401 (ISBN) ; Aashuri, H ; Narimannezhad, A ; Khosravani, A ; Kiani, M ; Sharif University of Technology
Trans Tech Publications Ltd 2008
Computer base and simulation technique have been applied for modeling the semi-solid die filling and part of the solidification process of aluminum A356 alloy. A fairly simple one-phase rheological model has been implemented into a fluid flow finite element software Procast, to solve the partial differential equations. This model is purely viscous nature and is implemented in the power law cut-off model of Procast. The constitutive parameters of this model were determined for a rheocast A356 alloy. Using these parameters and comparing the simulation results with experimental data showed good correlation with the model prediction. The designed die for rheocasting was applied for the...
Article Materials Science and Engineering A ; Volume 454-455 , 2007 , Pages 528-535 ; 09215093 (ISSN) ; Rajabi, M ; Nejati, E ; Khomamizadeh, F ; Sharif University of Technology
In this investigation, the effect of microstructural constituents on thermal fatigue resistance of A319 aluminum casting alloy was studied. For this purpose, both thermo-mechanical fatigue and thermal-shock fatigue experiments were performed in thermal cycling range between 40 and 250 °C. Following the results, samples with finer SDAS, lower porosity volume fraction and lower brittle intermetallic contents, as well as higher Si modification showed better thermal fatigue resistance. Moreover, T6 and T7 heat treatments appeared to be highly beneficial for thermal fatigue performance. According to the fractography analysis, porosities and coarse intermetallic phases were determined as the most...
Microstructure and mechanical properties of oxide-dispersion strengthened Al6063 alloy with ultra-fine grain structure, Article Metallurgical & Materials Transactions. Part A ; Mar2011, Vol. 42 Issue 3, p. 816-824 ; Simchi, A. (Abdolreza) ; Kim, H. S ; Sharif University of Technology
The microstructure and mechanical properties of the ultra-fine grained (UFG) Al6063 alloy reinforced with nanometric aluminum oxide nanoparticles (25 nm) were investigated and compared with the coarse-grained (CG) Al6063 alloy (~2 μm). The UFG materials were prepared by mechanical alloying (MA) under high-purity Ar and Ar-5 vol pct O2 atmospheres followed by hot powder extrusion (HPE). The CG alloy was produced by HPE of the gas-atomized Al6063 powder without applying MA. Electron backscatter diffraction under scanning electron microscopy together with transmission electron microscopy studies revealed that the microstructure of the milled powders after HPE consisted of ultra-fine grains...
Flow stress of 2024 aluminum alloy during multi-directional forging process and natural aging after plastic deformation, Article Materials Chemistry and Physics ; Volume 254 , 2020 ; Kazeminezhad, M ; Shadkam, A ; Sharif University of Technology
Elsevier Ltd 2020
The hardening behavior of heat treatable alloys during deformation is attributed to three mechanisms of forest dislocations, solid solution and precipitation hardening which hinder the motion of dislocations and increase the density of statistically stored dislocation. In this paper, a model for the flow stress of a 2024 heat treatable aluminum alloy during plastic deformation is developed combining the superposition of these three hardening mechanisms. This model was then implemented into the finite element model in order to evaluate the evolution of the flow stress of 2024 aluminum alloy during multi-directional forging (MDF). Subsequently, an equation is developed for evaluating the...
Article Journal of Materials Processing Technology ; Volume 205, Issue 1-3 , 26 August , 2008 , Pages 388-393 ; 09240136 (ISSN) ; Karimi Taheri, A ; Sharif University of Technology
In this paper, an Al-Mg-Si-Cu aluminum alloy was exposed to various heat treatment processes and the effect of precipitation hardening on hardness was investigated as a function of time and temperature. It was concluded that the variation in time and temperature can improve the hardness of the alloy. The work revealed that time and temperature play an important role in the precipitation hardening process of the alloy. To achieve the maximum hardness, an optimum aging cycle should be used which is heating at 180-190 °C for 15-18 h. Kinetics studies show an apparent activation energy of 58 kJ/mol. A relationship was derived which can be used to estimate the hardness at a given time and...
Article 2007 ASME Pressure Vessels and Piping Conference, PVP 2007, San Antonio, TX, 22 July 2007 through 26 July 2007 ; Volume 3 , 2008 , Pages 195-201 ; 0277027X (ISSN); 0791842819 (ISBN); 9780791842812 (ISBN) ; Farrahi, G. H ; Hoseini, S. H ; Sharif University of Technology
Real loading- unloading behavior of an A5083 aluminum alloy was recorded experimentally. This real behavior was incorporated in the variable material properties (VMP) numerical algorithm to predict residual stresses resulted from autofrettage and shrink fit in two kinds of autofrettage compound tubes. Using an analytical method, residual stresses induced by bore material removal via machining were calculated. Using developed VMP code and isotropic hardening rule in both autofrettage compound tubes, residual stresses resulted from shrink fit and autofrettage processes and via post machining, were estimated. Machining process simulation was performed for 10 mm bore material removal. ANSYS...
Article Iranian Journal of Materials Science and Engineering ; Volume 18, Issue 2 , 2021 ; 17350808 (ISSN) ; Ebadi, M ; Kokabi, A. H ; Sharif University of Technology
Iran University of Science and Technology 2021
Friction-Stir Processing (FSP) was applied on AA1050 Aluminum Alloy (AA) to find the highest mechanical properties among 28 combinations of the rotational and traverse speed (800-2000 rpm and 50-200 mm.min-1) and four different tool probe shapes (threaded, columnar, square and triangle). To this aim, the AA standard sheet went through a single pass of FSP. The 1600 rpm and 100 mm.min-1 with threaded tool probe was chosen as the best combination of rotational and traverse speed. Grain size at the Stirred Zone (SZ) was studied using Optical Microscopy (OM). The results showed that the SZ’s grain size was refined from 30 μm down to about 12 μm due to dynamic recrystallization during FSP. The...
Processing Nano Composite Structure of 1100 and 3004 Al Alloy Sheets Using ARB Technique and Study Influence of Heat Treatment on the Grain Structure, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous
At this study, nano structure sheet composite produced by1100 and 3004 strips using Accumulative role banding then mechanical and physical properties of the composites were investigated. After surface preparation, primary composite samples produced by putting different layers on each other and then rolling. The rolling was occurred in two steps; thickness reduction at first and second step were about 50% and 34%, respectively. ARB process were done till ninth cycle for Primary composite samples. To investigate mechanical properties of the samples, hardness, micro hardness and tensile strength tests have been done. Furthermore, micro structure of selective samples were studied by light...
Processing of Nanostructured Composite from Al1050 and Al2024 Via Aaccumulative Roll Bonding (ARB) and Study of Heattreatment Effects on its Microstructure and Mechanical Properties, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous
In this study nanostructured composite from Al1050 and Al2024 were manufactured via accumulative roll bonding (ARB). Process was conducted in two different ways. In one approach the Al2024 sheets were annealed and in the other they were solution treated (ST). The sheets were degreased by acetone and wire-brushed, and then one Al2024 was placed between two sheets of Al1050, so three pieces of sheets were stacked to be 3 mm in thickness. The stacked sheets were rollbonded to produce the primary composite sandwich with thickness of 1 mm. Then, this sandwich was cut in the half and the two halves were degreased and wire-brushed and stacked to be 2 mm in thickness. Roll-bonding was conducted...