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    The effect of SiC nanoparticles on the friction stir processing of severely deformed aluminum

    , Article Materials Science and Engineering A ; Vol. 602, issue , April , 2014 , p. 110-118 ; ISSN: 09215093 Sarkari Khorrami, M ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
    The 1050 aluminum sheets are severely deformed by two passes of the constrained groove pressing (CGP) process to obtain the strain of 2.32. Friction stir processing (FSP) is then performed on these specimens at two conditions of with and without SiC nanoparticles. Microhardness measurements indicate that in the state of FSP without any particle, the microhardness of stir zone is decreased due to the recrystallization and grain growth occurrence because of high stored strain energy in the CGPed specimens. In order to enhance the mechanical properties of the stir zone, SiC nanoparticles are used during FSP. Also, the effect of FSP pass number on the distribution of nanoparticles is... 

    Deformation behavior of 6061 aluminum alloy through tube channel pressing: Severe plastic deformation

    , Article Journal of Materials Engineering and Performance ; Volume 21, Issue 10 , 2012 , Pages 2099-2105 ; 10599495 (ISSN) Farshidi, M. H ; Kazeminezhad, M ; Sharif University of Technology
    Springer  2012
    The deformation behavior of solid solution-treated AA6061 tubes in a novel severe plastic deformation process named Tube Channel Pressing has been assessed. In order to do so, an analysis based on the finite element method and dislocation density model is utilized, and microhardness measurement is carried out to verify the trends of analysis results. By comparing FEM results with experimental data, the optimized geometrical parameters controlling the deformation behavior of the tube in tube channel pressing are determined to obtain the best strain homogeneity and minimum dimensional changes in tube  

    Mechanical properties of severely plastic deformed aluminum sheets joined by friction stir welding

    , Article Materials Science and Engineering A ; Volume 543 , 2012 , Pages 243-248 ; 09215093 (ISSN) Khorrami, M. S ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
    The severely plastic deformed aluminum sheets were joined by friction stir welding (FSW). The technique used for imposing the severe strain to the sheets was constrained groove pressing (CGP) process. The specimens with three different imposed strains by CGP, which lead to different initial microstructures, were joined at various rotation (. ω) and traveling (. V) speeds. The microhardness measurements and microstructure investigations were carried out. It was revealed that after FSW process of the specimens strained by CGP process, grain growth and correspondingly hardness reduction were observed at the stir zone. Also, transverse tensile test was performed at all conditions. For the CGPed... 

    Influence of stored strain on fabricating of Al/SiC nanocomposite by friction stir processing

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 46, Issue 5 , May , 2015 , Pages 2021-2034 ; 10735623 (ISSN) Khorrami, M. S ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
    Springer Boston  2015
    In this work, 1050 aluminum (Al) sheets were annealed and severely deformed by 1, 2, and 3 passes of constrained groove pressing process to obtain the various initial stored strain values of 0, 1.16, 2.32, and 3.48, respectively. Friction stir processing (FSP) was then applied using SiC nanoparticles to fabricate Al/SiC nanocomposite with approximately 1.5 vol pct reinforced particles. Microstructural examinations revealed that an increase in the initial stored strain of the base metal led to the formation of finer grain structure after 1 pass of FSP. The finer grain structure occurred in the stir zone where a sufficient amount of nanoparticles with a relatively proper distribution existed.... 

    Applicability of the FSEM for analyzing wire flat rolling process

    , Article Engineering Computations (Swansea, Wales) ; Volume 23, Issue 5 , 2006 , Pages 515-524 ; 02644401 (ISSN) Kazeminezhad, M ; Taheri, A. K ; Sharif University of Technology
    Purpose - The purpose of this paper is to present an assessment of the ability of combined finite and slab element method (FSEM) for analyzing the wire flat rolling process. Design/methodology/approach - Using the FSEM, the effective strain field of flat rolled wire is predicted for different reductions in height and frictional conditions. The validity of the method is assessed by performing the Vickers microhardness measurements on the flattened wire cross section. Also, the creation of macroscopic shear bands in cross section of the flat rolled wire is investigated and confirmed by microhardness and metallographic examinations. Moreover, the lateral spread and width of contact area are... 

    Microstructure and mechanical property change during FSW and GTAW of Al6061 alloy

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 44, Issue 5 , 2013 , Pages 2187-2195 ; 10735623 (ISSN) Fahimpour, V ; Sadrnezhaad, S. K ; Karimzadeh, F ; Sharif University of Technology
    The variation of morphology and mechanical properties of Al6061 automotive aluminum alloy due to friction stir welding (FSW) and gas tungsten arc welding (GTAW) was investigated by optical metallography, scanning electron microscopy, microhardness measurement, X-ray diffraction, tensile testing, and fractography. The center-line dendrite emergence and microhardness reduction in the heat-affected zone were observed in the GTAW process. Although similar microhardness reduction with respect to the base metal was observed in the FSW samples, higher HVs were obtained for the FSW rather than the GTAW process at almost all heat-affected locations. Ultimate tensile strengths of the FSW and the GTAW... 

    Thermal stability during annealing of friction stir welded aluminum sheet produced by constrained groove pressing

    , Article Materials and Design ; Volume 45 , 2013 , Pages 222-227 ; 02613069 (ISSN) Sarkari Khorrami, M ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
    The severely deformed aluminum sheets with strain of 2.32 were successfully joined by friction stir welding (FSW) process. Welding was carried out at various rotation speeds of 600, 800, and 1000. rpm at traveling speed of 200. mm/min corresponding to various revolution pitches of 0.33, 0.25, and 0.20. mm/r, respectively. In order to investigate the thermal stability of the joints, annealing was carried out at temperature of 200 °C for 1. h. Microstructure examinations revealed that severely deformed samples were quite unstable upon FSW process. However, during annealing it was found that in contrast to regions of heat affected zone (HAZ) and thermo mechanical affected zone (TMAZ) where... 

    Microstructure evolutions after friction stir welding of severely deformed aluminum sheets

    , Article Materials and Design ; Volume 40 , September , 2012 , Pages 364-372 ; 02641275 (ISSN) Sarkari Khorrami, M ; Kazeminezhad, M ; Kokabi, A. H ; Sharif University of Technology
    Elsevier  2012
    The microstructure evolutions of severely deformed aluminum sheets by Constrained Groove Pressing (CGP) after Friction Stir Welding (FSW) are investigated. To do so, the specimens are deformed in three different strains using CGP process which make different the initial microstructures. Then, the specimens are joined at various revolution pitches (traveling speed/rotation speed ratio) of 0.20, 0.25 and 0.33. mm/r. To understand the effect of initial strains on the properties of joints, the microhardness measurements and microstructure investigations of different areas from retreating to advancing sides of the joints are carried out. The results achieved from FSW of CGPed samples are compared... 

    Mechanical and electrochemical behaviors of butt-welded high temperature steel pipes

    , Article Engineering Failure Analysis ; 2016 ; 13506307 (ISSN) Daavari, M ; Vanini, S. A. S ; Fereiduni, E ; Rokni, M. H ; Sharif University of Technology
    Elsevier Ltd  2016
    In this study, fatigue, corrosion fatigue and electrochemical behaviors of butt-welded A106-B steel pipes were investigated. These pipes were subjected to mechanical and thermal cyclic stresses due to the internal pressure fluctuations and cooling-heating cycles. Residual stress measurements were carried out for three different depths through the thickness and were correlated to the microstructural observations and microhardness measurements. Results showed that the maximum tensile residual stresses existed at the boundary of weld metal and base metal because of the contraction-expansion effects resulting from phase transformations and cooling rate differences. Fatigue fractures occurred at... 

    Analysis and characterization of microstructural evolutions, mechanical response and fracture mechanism of laser welded Fe-Co-V ultra-thin foils

    , Article Optics and Laser Technology ; Volume 68 , 2015 , Pages 211-219 ; 00303992 (ISSN) Mostaan, H ; Shamanian, M ; Monirvaghefi, S. M ; Behjati, P ; Hasani, S ; Fathi Moghaddam, M ; Amiri, M ; Szpunar, J. A ; Sharif University of Technology
    Elsevier Ltd  2015
    The welding behavior of the Fe-Co-7 wt% V ultra-thin foils was examined using the Nd:YAG laser welding method. Scanning electron microscopy and electron backscattered diffraction were used to investigate microstructural changes and fracture mechanism of the weld joints. Tensile test and microhardness measurement were employed in order to study the mechanical behaviors of the welds. Microstructural observations indicated that a bimodal grain size distribution is seen in the fusion zone. It was found that the fracture surfaces of the welds consist of both cleavage sites and dimples. It was also revealed that the cleavage sites are mainly located in the coarse grain zone while numerous dimples... 

    Deposition of metallic molybdenum thin films on 304L steel substrate by SUT-PF

    , Article Surface and Coatings Technology ; 2016 ; 02578972 (ISSN) Hosseinzadeh, A ; Nazmabadi, M ; Vosoughi, N ; Sharif University of Technology
    Elsevier B. V 
    The present research work aims to employ plasma focus in order to deposit molybdenum (Mo) on the 304 stainless steel substrate. The processing parameters were shot numbers as well as the distance of substrate from the anode tip. Stereo, atom force microscopy (AFM) and field emission-scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDS) were used to study the deposited coatings. Microhardness measurements were also performed on the coatings. Results indicated that the plasma focus can be successfully applied to deposit Mo anode on the stainless steel substrate. The coatings contained discrete pores with sizes varying by processing parameters. The... 

    Fabrication, characterization and mechanical properties of hybrid composites of copper using the nanoparticulates of SiC and carbon nanotubes

    , Article Materials Science and Engineering A ; Volume 572 , 2013 , Pages 83-90 ; 09215093 (ISSN) Akbarpour, M. R ; Salahi, E ; Alikhani Hesari, F ; Simchi, A ; Kim, H. S ; Sharif University of Technology
    Copper based hybrid composites containing nano-sized silicon carbide and carbon nanotubes reinforcements with minimal porosity were fabricated via mechanical milling followed by hot pressing technique. Microstructures of the powders and consolidated materials were studied using scanning electron microscope, X-ray diffraction, Raman spectroscopy, and scanning transmission electron microscope. Microstructural characterization of the materials revealed that the addition of nanosized silicon carbide reinforcement lowered the grain growth rate and enhanced the homogenization during mechanical milling. Microhardness measurements and compression test showed considerable improvements in mechanical... 

    Transient liquid phase bonding of dual phase steels using Fe-based, Ni-based, and pure Cu interlayers

    , Article Journal of Manufacturing Processes ; Volume 30 , 2017 , Pages 106-115 ; 15266125 (ISSN) Azqadan, E ; Ekrami, A ; Sharif University of Technology
    Transient liquid phase (TLP) bonding is a joining process which combines benefits of diffusion bonding and brazing. Therefore, this method has widely been used in joining of materials which are sensitive to fusion welding. Interlayer composition, as one of the most important factors of TLP bonding, can affect the bonding region composition, microstructure, and hence mechanical properties of the joint. In this research, Fe-based, Ni-based, and commercially pure Cu interlayers are used to bond low-carbon steel components which are then heat treated to produce dual phase steel. The present work focuses on two main goals. Firstly, drawing a comparison of microstructure and mechanical properties... 

    The effect of current density on microstructural homogeneity, hardness, fracture toughness and electrochemical behavior of electrodeposited Cu-0.5Co/WC nano-composite coating

    , Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3505-3511 ; 10263098 (ISSN) Khaleghpanah, Sh ; Abachi, P ; Dolati, A ; Sharif University of Technology
    The Cu-0.5Co/WC nano-composite coating was synthesized on CP-copper substrate using Direct Current (DC) electrodeposition method. In this work, it was tried to increase the hardness of surface without considerable degradation of copper's particular physical properties such as electrical conductivity. The effect of current density on microstructural homogeneity, hardness, fracture toughness, and electrochemical behavior of coating was investigated. The copper plates with the purity of 99.99% were used as electrodes. The electrolyte consists of tungsten carbide particles (30 g/l), copper sulfate (200 g/l), sulfuric acid (50 g/l), cobalt sulfate (50 g/l), and Sodium Dodecyl Sulfate (SDS) (0.3... 

    Effect of dwell time on joint interface microstructure and strength of dissimilar friction stir spot-welded al-5083 and st-12 alloy sheets

    , Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 48, Issue 4 , 2017 , Pages 1744-1758 ; 10735623 (ISSN) Fereiduni, E ; Movahedi, M ; Kokabi, A. H ; Najafi, H ; Sharif University of Technology
    Springer Boston  2017
    Joining of Al-5083 alloy sheet to St-12 steel sheet was performed using a new friction stir spot welding (FSSW) technique in which the tool pin tip did not enter lower steel sheet. Effect of dwell time on the microstructure and mechanical properties of the joints was studied by various methods including microhardness measurements, shear test, stereo and light microscopy as well as scanning and transmission electron microscopy (SEM and TEM). Results indicated that compared to the conventional FSSW process, stronger joints can be achieved by this FSSW technique. Cross-sectional observation of the failed specimens indicated the occurrence of final fracture from the circumference of the tool pin... 

    Effect of angular position on the quality of dense plasma focus-based additive layer manufactured molybdenum coatings

    , Article International Journal of Advanced Manufacturing Technology ; Volume 99, Issue 9-12 , 2018 , Pages 2717-2725 ; 02683768 (ISSN) Fereiduni, E ; Hosseinzadeh, A ; Nazmabadi, M ; Vosoughi, N ; Sharif University of Technology
    Springer London  2018
    The present research aims at depositing molybdenum on stainless steel substrate using dense plasma focus (DPF) device. The varying parameter was the angular position of substrate surface from the anode tip. The deposited layers were characterized using various analyses such as X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and microhardness measurements. Microstructural observations revealed that the deposited coatings had rough surfaces containing holes as well as a stripe-featured structure covering the whole surface including the interior regions of the holes and the regions among them.... 

    Study of nanocrystallization in FINEMET alloy by active screen plasma nitriding

    , Article Journal of Alloys and Compounds ; Volume 491, Issue 1-2 , 2010 , Pages 487-494 ; 09258388 (ISSN) Shivaee, H. A ; Madaah Hosseini, H. R ; Memarzadeh Lotfabad, E ; Roostaie, S ; Sharif University of Technology
    The nanocrystallization process of amorphous Fe73.5Si13.5B9Nb3Cu 1 was investigated by active screen plasma nitriding (ASPN) treatment at temperatures ranging from 410 °C to 560 °C for 3 h in two gas mixtures of 75% N2-25% H2 and 25% N2-75% H2 at 5 mbar atmosphere. The amorphous ribbons were then annealed under vacuum at the same time and temperatures mentioned above. The structure of the samples was analyzed using various techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). Microhardness measurements, electrical resistivity and Vibrating Sample Magnetometer (VSM) were used to study mechanical, electrical and magnetic... 

    Microstructural features, texture and strengthening mechanisms of nanostructured AA6063 alloy processed by powder metallurgy

    , Article Materials Science and Engineering A ; Volume 528, Issue 12 , 2011 , Pages 3981-3989 ; 09215093 (ISSN) Asgharzadeh, H ; Simchi, A ; 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... 

    Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

    , Article Materials Characterization ; Volume 101 , March , 2015 , Pages 189-207 ; 10445803 (ISSN) Mohammadi, J ; Behnamian, Y ; Mostafaei, A ; Izadi, H ; Saeid, T ; Kokabi, A. H ; Gerlich, A. P ; Sharif University of Technology
    Elsevier Inc  2015
    Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560-1400 r/min and 16-40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS)... 

    Structural and magnetic study of active screen plasma nitrided Fe 73.5Si13.5B9Nb3Cu1and Fe77Si11B9Nb2.4Cu0.6 ribbons

    , Article Scientia Iranica ; Volume 17, Issue 1 F , 2010 , Pages 12-22 ; 10263098 (ISSN) Memarzadeh Lotfabad, E ; Madaah Hosseini, H.R ; Asghari Shivaee, H ; Roostaie, S ; Sharif University of Technology
    The comparative study of Active Screen Plasma Nitriding (ASPN) treatment of two Finemet-type alloys with the compositions of Fe73.5Si 13.5B9Nb3Cu1 and Fe 77Si11B9Nb2.4Cu0.6 was investigated in different temperatures ranging from 410°C to 56°C. Differential Scanning Calorimetry (DSC), X-Ray Diffractometery (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), electrical resistivity, microhardness measurements and magnetic characterization by a Vibrating Sample Magnetometer (VSM) were utilized to characterize the treated samples. The comparison of the DSC data for the alloys suggested that the smaller amount of Nb as a growth inhibitor shifted the crystallization...