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Journal of Materials Science & Technology 2014年第8期30卷 826-834页

作者： h.Barekatain M.Kazeminezhad a.h.kokabi Department of Materials Science and Engineering Sharif University of TechnologyAzadi AvenueTehranIran

In this study,AA 1050 aluminum alloy and commercially pure copper in annealed and severely plastic deformed conditions were *** technique used for imposing the severe strain to the sheets was constrained groove pressing（CGP） *** annealed and severely plastic deformed sheets were subjected to friction stir welding（FSW） at different rotation and traverse *** was placed in advancing *** offset of approximately 1 mm was used toward Al side for all welds.A range of welding parameters which can lead to acceptable welds with appropriate mechanical properties was *** the FSWed CGPed samples,it was observed that the welding heat input caused grain growth and decrease in hardness value at Al side of the stir *** was found that,generally the weakest parts of weld joints of annealed and CGPed samples were Al base metal and stir zone,*** investigations showed that several forms of intermetallic compounds were produced.

关键词： Friction stir welding Severe plastic deformation Aluminum Copper Intermetallics

Effects of heat input in friction stir welding on microstructure and mechanical properties of AA3003-h18 plates

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Transactions of Nonferrous Metals Society of China 2015年第7期25卷 2147-2155页

作者： B.ABNAR M.KAZEMINEZhAD a.h.kokabi Department of Materials Science and Engineering Sharif University of Technology

The non-heat-treatable AA3003-h18 plates were joined by friction stir welding（FSW） to achieve a proper joint by optimizing the welding *** this purpose,the effects of heat input on microstructure and mechanical properties of the welded samples were investigated by changing the ratios of rotational speed（800-1200 r/min） to travel speed（40-100 mm/min）（w/v）.It was revealed that the grain growth rate was strongly increased with the increase of the heat input by rotational speed at constant travel speed,while the grain growth rate was slightly increased with the increase of the heat input by travel speed at constant rotational ***,hardness reduction was observed in the stir zone at higher rotational speed compared with that at lower *** interesting observation was that various welding parameters do not have noticeable effect on the tensile strength of the FSW ***,it has been observed that the fracture location of tensile test specimens was placed in the heat-affected zone（hAZ）on the advancing side at lower travel speed,while at higher travel speed,it was placed at the hAZ/thermomechanical affected zone（TMAZ） interface on the retreating side.

关键词： AA3003-h18 alloy friction stir welding heat input microstructure mechanical properties

Improvement in the mechanical properties of Al/SiC nanocomposites fabricated by severe plastic deformation and friction stir processing

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International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 297-308页

作者： M.Sarkari Khorrami M.Kazeminezhad Y.Miyashita a.h.kokabi Department of Materials Science and Engineering Sharif University of Technology Department of Mechanical Engineering Nagaoka University of Technology

Severely deformed aluminum sheets were processed by friction stir processing(FSP) with Si C nanoparticles under different conditions to improve the mechanical properties of both the stir zone and the heat affected zone(hAZ).In the case of using a simple probe and the same rotational direction(RD) of the FSP tool between passes,at least three FSP passes were required to obtain the appropriate distribution of ***,after three FSP passes,fracture occurred outward from the stir zone during transverse tensile tests;thus,the strength of the specimen was significantly lower than that of the severely deformed base material because of the softening phenomenon in the *** improve the mechanical properties of the hAZ,we investigated the possibility of achieving an appropriate distribution of nanoparticles using fewer FSP *** results indicated that using the threaded probe and changing the RD of the FSP tool between the passes effectively shattered the clusters of nanoparticles and led to an acceptable distribution of Si C nanoparticles after two FSP *** these cases,fracture occurred at the hAZ with higher strength compared to the specimen processed using three FSP passes with the same RD between the passes and with the simple *** fracture behaviors of the processed specimens are discussed in detail.

关键词： friction stir processing plastic deformation aluminum silicon carbide nanocomposites mechanical properties

Effect of welding parameters on semisolid stir welding of Mg-9Al-1Zn magnesium alloy

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Transactions of Nonferrous Metals Society of China 2016年第10期26卷 2586-2594页

作者： V.A.hOSSEINI h.AAShURI a.h.kokabi Department of Engineering Science University West Materials Science and Engineering Department Sharif University of Technology

Semisolid stir welding of AZ91 was investigated with focus on the joining temperature and rotational speed. An Mg-25%Zn interlayer was located between two AZ91 pieces and the system was heated up to the semisolid state of base metal and interlayer. The weld seam was stirred using a drill-tip at different joining temperatures and rotational speeds. Optical and scanning electron microscopes were employedto study microstructure, cavity formation, and segregation. hardness profile and shear punch test werealso employed to rank the welds based on their quality and homogeneity. Results showed that the lowest cavity content （2.1%） withthemaximum ultimate shear strength （about 188 MPa） was obtained in weld with the joining temperatureof530℃ and the rotational speedof1600 r/min. Low quality welds and a reduction of ultimate shear strength were observed at very high orlow rotational speeds and joining temperatures. The process, in conclusion, produced close mechanical properties to those of thebase metal and homogenous quality throughout the joint, when the intermediate temperature and rotational speeds were employed.

关键词： Mg-Al-Zn alloy mechanical stirring semisolidstir welding

Butt joining of Al-Cu bilayer sheet through friction stir welding

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Transactions of Nonferrous Metals Society of China 2012年第12期22卷 2925-2929页

作者： R.BEYGI M.KAZEMINEZhAD a.h.kokabi Department of Materials Science and Engineering Sharif University of Technology

Butt joining of Al–Cu bilayer sheet produced by cold roll bonding was studied through friction stir welding (FSW). A defect free joint was obtained. Flow patterns and mixing of two layers during FSW were investigated. Microstructural investigations and hardness profile measurements were carried out. It is shown that material flow in stir zone leads to the formation of banding structure in Cu layer at advancing side. Traces of Al particles along with Al–Cu intermetallic compounds exist in the fined grain region of this banding structure which leads to higher hardness values.

关键词： bilayer sheet Al-Cu sheet friction stir welding microstructure

Semisolid joining of aluminum A356 alloy by partial remelting and mechanical stirring

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1792-1798页

作者： S.M.J.ALVANI h.AAShURI A.kokabi R.BEYGI Materials Science and Engineering Department Sharif University of Technology

A method to reach the globular weld structure of A356 aluminum alloy using stirring the localized semisolid zone during butt-joining is *** the heat conductivity of this alloy is very high, the accurate controlling of temperature during joining must be considered.A gas heating system was used to heat up the nitrogen gas up to the required temperature.A dried and free oxygen gas was prepared when a stream of nitrogen gas could pass closely around a hot *** and pure nitrogen gas flow through a precise ceramic nozzle was used to create a localized semisolid *** this stage a fine stirrer was introduced into the weld seam in order to mix the two sides into a single uniform *** were moved in direction of joint line by a small trolley to avoid the deviation of nozzle from the joint line and its distance and angle from the substrate.A fixture system was used to hold two substrates together on the trolley.A narrow hot plate was located on the trolley to heat up the joint line due to high heat conductivity of *** of gas temperature was investigated on the microstructure and mechanical properties of weld *** showed that increase in temperature promoted the final welding properties, and also at liquid fractions less than 50% joining was not fully *** best mechanical properties were achieved with liquid fraction of about 70%.

关键词： semisolid joining A356 localized stirring shear punch semi-solid holding thermal treatment

Mechanisms of joint formation throughout semisolid stir welding of AZ91 magnesium alloy

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Transactions of Nonferrous Metals Society of China 2013年第9期23卷 2585-2590页

作者： V. A. hOSSEINI h. AAShURI A. kokabi Materials Science and Engineering Department Sharif University of Technology

Joining in the semisolid state is considered a possible method to join alloys to each other. The mechanisms taking part in semisolid stir welding of AZ91 alloys were investigated. Two 7.5 mm-thick AZ91 pieces and a 2 ram-thick Mg-25%Zn interlayer piece were placed in a heating plate. After holding for 3 min at a desired temperature, the weld seam was stirred by a rotational tool. The heating plate was travelled on a trolley at a constant speed of 4.6 cm/min. In addition, one sample was welded without interlayer. Evolution of welding as a function of stirring rate, tool shape and temperature was studied throughout this welding process with scanning electron and optical microscopes. Interlayer decreases the joining temperature and assists to investigate the possible semisolid stir welding mechanisms. Increasing temperature and stirring rate, and using round stirrer instead of grooved stirrer increase the stir zone width. The results show that some possible mechanisms are helpful to achieve a proper metallurgical bonding in the welding process, such as oxide layer disruption, liquid phase blending, globule joining, and liquid penetration to the base metal, merging a group of globule into stir zone from the base metal.

关键词： AZ91 magnesium alloy semisolid joining Mg-Zn interlayer mechanical stirring metallurgical bonding

Dynamic stress concentration in an infinitely long cylindrical cavity due to a point spherical source embedded within a fluid-saturated poroelastic formation of infinite extent

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 139-156页

作者： h.hOSSEINI O.BALILAShAKI Department of Mechanical Engineering Faculty of EngineeringGolestan University

The effects of a harmonically exciting monopole source on an infinitely long cylindrical cavity embedded entirely within a fluid-saturated poroelastic formation of infinite extent are examined theoretically. It is assumed that the source is located outside the cavity at a specified distance from the borehole axis. The magnitudes of the hoop and radial stresses beside the pore pressures exerted on the interface and inside the porous medium surrounding the borehole are calculated and discussed. Biot's poroelastic modeling along with three types of boundary conditions for the cylindrical interface including the ideal fluid, empty borehole, and rigid inclusion with a hard boundary is employed for the analysis. Utilizing a proper translational addition theorem for expressing the incident spherical wave in terms of cylindrical wave expansions, the proposed boundary conditions at the interface are satisfied. Stresses are formulated by means of wave potential functions in a three-dimensional(3D) manner. The effects of the frequency and the radial distance between the source and borehole on the induced stresses are examined for the first cylindrical modes over frequency spectra. Two permeability conditions for the interface and three types of soils for the porous formation are considered throughout the analysis. To give an overall outline of the study, a numerical example is presented. The results clearly indicate that the distance is a key parameter and has considerable effects on the induced stress values. In addition, the interface permeability condition and soil characteristics play an important role in determining the dynamic response of the borehole. Finally,the obtained results are compared with the relevant analyses existing in the literature for some limit cases, and good agreement is achieved.

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Neuroinflammation as a therapeutic target in huntington's disease

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Neural Regeneration Research 2025年第3期20卷 817-818页

作者： Andrea Kwakowsky Thulani h.Palpagama Center for Brain Research and Department of Anatomy and Medical Imaging Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand Pharmacology and Therapeutics School of MedicineGalway Neuroscience CentreUniversity of GalwayGalwayIreland

In 1872, George huntington presented his essay “On Chorea” to the Meigs and Mason Academy of Medicine and, in doing so, detailed a disease that would later bear his name. huntington's disease(hD) is a genetic, neurodegenerative disease that manifests as the loss of motor control,cognitive impairment,and mood and psychiatric changes in paents.

关键词： huntington inflammation Medicine

Glial response in the midcingulate cortex in huntington’s disease

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Neural Regeneration Research 2025年第1期20卷 207-208页

作者： Thulani h.Palpagama Andrea Kwakowsky Center for Brain Research and Department of Anatomy and Medical Imaging Faculty of Medical and Health SciencesUniversity of AucklandAucklandNew Zealand Pharmacology and Therapeutics School of MedicineGalway Neuroscience CenterUniversity of GalwayGalwayIreland

huntington’s disease(hD)is a genetic disease characterized by the progressive degeneration of the striatum and *** can present with a variety of symptoms that can broadly be classified into motor symptoms,inclusive of choreatic movements and rigidity,mood and psychiatric symptoms,such as depression and apathy,and cognitive symptoms,such as cognitive *** causal mutation underlying hD results from an expansion of a CAG repeat sequence on the IT15 gene,resulting in the formation and accumulation of a mutant huntingtin protein.

关键词： huntington degeneration cortex