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magnesium nanocomposites:An overview on time-dependent plastic(creep) deformation

Defence Technology（防务技术） 2019年第2期15卷 123-131页

作者： m.haghshenas m.Gupta Department of mechanical Engineering University of North Dakota Department of mechanical Engineering National University of Singapore

magnesium(mg) nanocomposites are created when nano-size particles are embedded into the mg(or mg alloy) matrix. The mg nanocomposites, cited as high-strength energy-saving materials of future, are a group of emerging materials with excellent combination of strength and ductility and superior specific strength property(strength-to-weight ratio). Having said this, mg nanocomposites are considered as promising replacement for other structural alloys(i.e. aluminum and titanium) wherever low density and high strength are required, i.e. transportation, aerospace, defense, etc. To be able to apply this group of materials for real components, different failure mechanisms at ambient and elevated temperatures under static and dynamic loading condition must be well documented. Compared with other metals and alloys,rate-dependent plastic deformation(creep), at ambient and elevated temperatures, of these novel materials is not yet well studied which seems a tangible lack of knowledge. This is required since the materials in service are often exposed to medium and elevated temperatures and/or static loads for long duration of time and this encourages creep failure on them. To this end, the information and the controlling mechanisms on time/temperature-dependent response of the material need to be developed to be able to predict the response of the mg nanocomposites where the materials are under creep conditions. This paper aims at providing an overview on(i) creep-resistant mg alloys(as matrix) and their chemical compositions, and(ii) responses of the mg nanocomposites at different creep conditions(time and temperature). The controlling mechanisms contributing to the strength and ductility of the mg nanocomposites due to the presence of the nanoparticles have been reviewed briefly in the present article. In this paper both traditional(uniaxial) and depth-sensing indentation creep of mg nanocomposites are reviewed. Also, some fundamental questions and possible explanations have be

关键词： mg nanocomposite Creep Strength Reinforcement Nanoparticles

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Design of experiment study on hardness variations in friction stir welding of Am60 mg alloy

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Journal of magnesium and Alloys 2018年第3期6卷 215-228页

作者： S.Richmire K.Hall m.haghshenas Department of mechanical Engineering University of North DakotaGrand ForksND 58202USA Department of Chemical Engineering University of North DakotaGrand ForksND 58202USA

Identification of process parameters,their effects and contributions to the outcomes of the system using experimental approach could be a daunting,time consuming,and costly *** proper statistical methods,i.e.,Taguchi method,could significantly reduce the number of required experiments and statistical significance of the parameter can be *** stir welding is one of those welding techniques with many parameters which have different effects on the quality of the *** friction stir welding the tool rotational speed(RPm)and transverse speed(mm/min)influence the strength(i.e.,hardness distribution)of the stirred *** this study,these two factors are investigated to determine the effect they will have on the hardness in the stirred zone of the friction stir welds and how the two factors are related to one another for as-cast magnesium alloy Am60 with nominal chemical composition of mg-(5.5-6.5)Al-(0.24-0.6)*** data was taken at three different tool rotational speeds and three different transverse *** data obtained was then analyzed using a 32 factorial design to find the contribution of these *** was determined that both tool rotational speed and transverse speed possess significant effects on the stir zone ***,the interactions between the two factors were statistically assessed.

关键词： Am60 mg alloy Design of experiment(DOE) Statistical method Friction stir welding

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Texture evaluation in warm deformation of an extruded mg-6Al-3Zn alloy

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Journal of magnesium and Alloys 2016年第2期4卷 89-98页

作者： m.Kavyani G.R.Ebrahimi m.Sanjari m.haghshenas department of materials and polymer engineering hakim sabzevari universitysabzevariran department of mining and materials engineering mcgill universitymontrealcanada department of mechanical engineering university of north dakotagrand forksusa

To assess the effect of strain and strain rate on texture evolution of an extruded mg–6Al–3Zn alloy,compression tests were carried *** were prepared in the extrusion direction(ED)and normal direction(ND).The compression tests were performed at 250℃ and with different strain rates of 0.01 sec−1 and 1 sec−1 and different *** observation and texture investigation show that at early stages of deformation,extension twins lead to the development of strong basal texture intensity along rolling direction(RD)in ED samples and contraction twins result in texture evolution along transverse direction(TD)in ND ***,microstructural investigation at high strains reveals that dynamic recrystallization occurs in both samples and consequently the basal texture intensity has been decreased.

关键词： Extruded magnesium alloy Deformation texture Twinning Recrystallization

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AZ91镁合金的热力行为和显微组织演化(英文)

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Transactions of Nonferrous metals Society of China 2012年第9期22卷 2066-2071页

作者： G. R. EBRAHImI A. R. mALDAR H. mONAJATI m. haghshenas Department of materials Engineering Faculty of Engineering Ferdowsi University of Mashhad Department of materials Engineering Sabzevar Tarbiat Moallem University Department of materials Engineering Islamic Azad University Department of mechanical and materials Engineering Western University

研究AZ91镁合金在热压缩过程中的流变行为和显微组织演化。在350～425℃对试样进行热压缩变形。在应变速率为0.1 s-1时,应变分别为峰应变、0.3和0.5。使用光学和扫描电子显微镜研究显微组织的演化。结果表明, 在压缩过程中再结晶晶粒沿... 详细信息

研究AZ91镁合金在热压缩过程中的流变行为和显微组织演化。在350～425℃对试样进行热压缩变形。在应变速率为0.1 s-1时,应变分别为峰应变、0.3和0.5。使用光学和扫描电子显微镜研究显微组织的演化。结果表明, 在压缩过程中再结晶晶粒沿预先存在的晶界形核;动态再结晶晶粒的数量随着应变的增大呈指数增加,且服从Avrami方程;动态再结晶晶粒的尺寸在开始时增大,达到最大值后开始减少。

关键词： AZ91镁合金热压缩显微组织演化再结晶峰应变

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Genetic diversity of HCV among various high risk populations(IDAs,thalassemia,hemophilia,HD patients) in Iran

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Asian Pacific Journal of Tropical medicine 2013年第7期6卷 556-560页

作者： Rafiei A Darzyani Azizi m Taheri S haghshenas mR Hosseinian A makhlough A molecular and Cell Biology Research Center.Faculty of medicine Mazandaran University of Medical Sciences18KM Khazar BlvdKhazar Sq.SariIran Department of Internal medicine Faculty of MedicineMazandaran University of Medical SciencesSari.Iran Nephrology Ward Department of Internal MedicineFaculty of MedicineMazandaran University of Medical SciencesSari.Iran

Objective:To determine the patterns of distribution of HCV genotypes among high risk population in north of ***:A cross-sectional study was conducted on 135 HCV RNA-positive high risk individuals including thalassemia,hemophilia,patients under hemodialysis and intravenous drug *** genotypes were determined based on amplification with type-specific primers ***:Among the 187 anti-HCV positive samples,only 135 (72.2%)gave HCV-RNA *** all,the most identified HCV type was genotype 3a(51.1%) followed by 1a(27.4%),1b(8.2%).Sixteen(11.9%)out of 135 HCV RNA-positive participants have infected with more than one genotype or subtypes as follow:1a/1b in 11(8.2%),2/3a in 3 (2.2%),and 1a/1b/3a in 2(1.5%).Stratification of participants revealed that HCV subtype 3a was more prominent in thalassemia,hemophilia and HD patients but 1a and 1b were frequent in intravenous drug ***:This study is the first report on HCV genotypes among Iranian subjects with different exposure categories resided in *** genotype 3a was found to be the most frequent genotype in thalassemia,hemophilia,and hemodialysis patients but not in *** the addiction age is decreasing in Iran and a lot of addicts are *** might change the subtype pattern of HCV in general population.

关键词： HCV Thalassemia Hemophilia Hemodialysis Intravenous drug addicts Iran

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Statistical Analysis of Sidelobes in Random Phase-modulated Radars

Statistical Analysis of Sidelobes in Random Phase-Modulated ...

引用

2011 CIE International Conference on Radar(RADAR 2011)

作者： H.haghshenas Jariani m.Bahadori E.Tohidi m.Nazari majd m.m.Nayebi Department of Electrical Engineering Sharif University of Technology

Target detection in noise radar is always done by computing cross-correlation between transmitted and received signals. In this process, side lobes of a strong target emerge and make some troubles in detection of weak ones （masking Effect）. Therefore, finding methods to suppress this effect becomes important. These methods can be implemented at the transmitter or receiver or at both to achieve more improvement. There are many new methods developed for the receiver side and a few methods applicable at the transmitter side. The main idea of suppressing side lobes at the transmitter is to design a specific noise signal instead of using purely random noise. In this paper we begin with introducing criteria for side lobe suppression and then the statistics of side lobes are examined to see how much suppression is achievable.

关键词： Noise Radar masking Effect Side lobe

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