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Effect of ECAP consolidation temperature on the microstructure and mechanical properties of Al-Cu-Ti metallic glass reinforced aluminum matrix composite

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Journal of Materials Science & Technology 2017年第9期33卷 1031-1038页

作者： M.R.Rezaei S.G.Shabestari S.H.razavi School of Metallurgy and Materials Engineering Iran University of Science and Technology (IUST) Center of Excellence for High Strength Alloys Technology (CEHSAT) School of Metallurgy and Materials EngineeringIran University of Science and Technology (IUST)

Al;Cu;Ti;metallic glass（AMG） reinforced Al matrix composites were consolidated by equal channel angular pressing（ECAP） process. The effects of ECAP consolidation temperature ranging from room temperature to just below the first crystallization temperature of metallic glass on the consolidation of composites were investigated in terms of the relative densities, structural evolutions and mechanical properties of composites. Some intermetallic compounds included Al;CuTi;, Al;Ti and Al;Cu;precipitated from metallic glass particles at consolidation temperature of 300?C. Consolidation temperature did not affect the matrix grains size of the composite. Quantitative analysis revealed that the distribution of reinforcing particles was considerably dependent on consolidation temperature. Density of the composite was increased by increasing the consolidation temperature to 250?C. The composite consolidated at250?C through ECAP process, exhibited the best combination of yield strength and ductility of 184 MPa and 48%, respectively.

关键词： Al matrix composite(AMC) Equal channel angular pressing(ECAP) Consolidation temperature Glass particles

Single neutron hole entropy in ^(105)Cd and ^(111)Cd

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Nuclear Science and Techniques 2015年第5期26卷 98-101页

作者： Z.Moradipoor R.razavi Physics Group North Tehran Branch Islamic Azad University Department of Physics Faculty of Science Imam Hossein Comprehensive University

The nuclear level density and entropy were calculated for105 Cd,106Cd,111 Cd and112Cd based on the Back Shifted Fermi Gas(BSFG) model and the Constant Temperature(CT) model. Then, the entropies were extracted in the microcanonical ensemble according to recent experimental data on nuclear level density measured by the Oslo group for these nuclei and are compared with their corresponding macroscopic calculations. Entropies of the neutron hole were estimated from the entropy difference between the odd-mass and even-even nuclei. The results reveal that the CT model describes better the extracted microcanonical results.

关键词：熵差中子微正则系综黑洞核能级密度 T模型费米气体实验数据

Effect of Solid Solution Supersaturation on Precipitation of γ′ in Rapidly Quenched Ni-Al Binary Alloys

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Journal of Materials Science & Technology 2009年第1期25卷 130-134页

作者： A. Samadi A. Abdollah-zadeh S. Behrouzghaemi S.H. razavi Department of Materials Engineering Tarbiat Modarres University P.O. Box 14115-143 Tehran Iran Department of Materials and Metallurgical Engineering Iran University of Science and Technology (IUST) Narmak#16846 Tehran Iran

The effect of solid solution supersaturation on the precipitation of γ＇ in rapidly quenched Ni-AI binary alloys containing 11.6, 14.2 and 16.5 at. pct AI was investigated. The samples were solutioned at 1250℃, quenched in iced brine, and then analyzed by electron microscopy and XRD （X-ray diffraction） techniques. In Ni-11.6 at. pct Al alloy, ordering and phase separation took place simultaneously, resulting in a uniform distribution of γ＇. A transition from uniform to bimodal γ＇ phase distribution occurred in the composition range between 14.2 and 16.5 at. pct Al. This transition was accompanied by changes in the morphology of γ＇ precipitates. The microstructural observations were discussed in view of both kinetics and crystallographic considerations.

关键词： Ni-Al system Heat treatment γ' precipitation Lattice mismatch

Characterization and corrosion behavior of Al-Co-rare earth(Ce-La)amorphous alloy

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Journal of Rare Earths 2023年第5期41卷 771-779,I0006页

作者： Seyed Ali Mousavi Sayed Hamid Hashemi Ali Ashrafi Reza Shoja razavi Seyyed Mehdi Ghazi Mirsaeed Faculty of Materials and Manufacturing Technologies Malek Ashtar University of TechnologyTehran167885611Iran Department of Materials Engineering Malek Ashtar University of TechnologyIsfahanShahin-shahrIran Department of Materials Engineering Isfahan University of TechnologyIsfahan***Iran

A new Al-based amorphous alloy with excellent corrosion resistance and high thermal stability was produced in the Al-Co-RE(Ce-La)*** this regard,two different amorphous-nanocrystalline ribbons:Al_(87.6)-Co_(6.4)-Ce_(3.8-)La_(2.2)(M_(1))and Al_(82.3)-Co_(10.1)-Ce_(4.8)-La_(2.8)(M_(2))were prepared using melt *** results reveal the supercooled liquid region(ATx)of 218℃which shows that the M2alloy has higher thermal stability in comparison to the *** M2ribbons present the superior corrosion resistance because of the formation of amorphous *** icorr,Ecorr,Epit,and Epit-Ecorrvalues of fully amorphous Al-Co-Ce-La metallic ribbons have a better trend of anti-corrosion performance compared to other crystalline and amorphous aluminum alloys.

关键词： Amorphous alloys Melt-spinning Rare earth metal Corrosion behavior

Phenological Stage, Plant Biomass, and Drought Stress Affect Microbial Biomass and Enzyme Activities in the Rhizosphere of Enteropogon macrostachyus

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Pedosphere 2019年第2期29卷 259-265页

作者： Kevin Z.MGANGA Bahar S.razavi Muhammad SANAULLAH Yakov KUZYAKOV Department of Soil Science of Temperate Ecosystems Institute of Soil Science University of G?ttingen Department of Range and Wildlife Sciences South Eastern Kenya University Department of Agricultural Soil Science Institute of Soil Science University of G?ttingen Institute of Soil and Environmental Sciences University of AgricultureFaisalabad Institute of Environmental Sciences Kazan Federal University

Indigenous grasses have been effectively used to rehabilitate degraded African drylands. Despite their success, studies examining their effects on soil bioindicators such as microbial biomass carbon(C) and enzyme activities are scarce. This study elucidates the effects of drought stress and phenological stages of a typical indigenous African grass, Enteropogon macrostachyus, on microbial biomass and enzyme activities(β-glucosidase, cellobiohydrolase, and chitinase) in the rhizosphere soil. Enteropogon macrostachyus was grown under controlled conditions. Drought stress(partial watering) was simulated during the last 10 d of plant growth, and data were compared with those from optimum moisture conditions. The rhizosphere soil was sampled after 40 d(seedling stage), 70 d(elongation stage), and 80 d(simulated drought stress). A high root:shoot ratio at seedling stage compared with elongation and reproduction stages demonstrated that E. macrostachyus invested more on root biomass in early development, to maximise the uptake of nutrients and water. Microbial biomass and enzyme activities increased with root biomass during plant growth. Ten-day drought at reproduction stage increased the microbial biomass and enzyme activities, accompanying a decrease in binding affinity and catalytic efficiency. In conclusion, drought stress controls soil organic matter decomposition and nutrient mobilization, as well as the competition between plant and microorganisms for nutrient uptake.

关键词： African grass catalytic efficiency cellobiohydrolase chitinase β-glucosidase nutrient uptake optimum moisture soil bioindicators

Iranian healthcare professionals' perspectives about factors influencing the use of telemedicine in diabetes management

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World Journal of Diabetes 2018年第6期9卷 92-98页

作者： Haleh Ayatollahi Nader Mirani Fatemeh Nazari Narjes razavi School of Health Management and Information Sciences Iran University of Medical SciencesTehran ***Iran Zanjan University of Medical Sciences Zanjan ***Iran School of Nursing and Midwifery Iran University of Medical SciencesTehran ***Iran

AIM To identify factors influencing the use of telemedicine in diabetes management from the perspectives of hea-lthcare *** This was a quantitative study that was conducted in 2016. The participants were 240 nurses and 55 physicians from three teaching hospitals as well as from one endocrinology and metabolism research center. No sampling method was used and the data were collected by using a five-point(1 to 5) Likert scale questionnaire, which had 37 questions. Descriptive and inferential statistics(Mann-Whitney U test) were used to analyze the *** The findings showed that both physicians(4.06 ± 0.69) and nurses(4.02 ± 0.61) tended to use telemedicine technology for managing diabetes. Overall, the lowest mean value for physicians(3.79 ± 0.82) was related to the compatibility of telemedicine with other clinical activities in diabetes management. For nurses, the lowest mean value pertained to the usefulness of telemedicine in diabetes management(3.99 ± 0.53) and their attitude toward using this technology(3.99 ±0.65).CONCLUSION Although physicians and nurses agreed on using te-lemedicine technology in diabetes management, it is necessary to consider their concerns prior to the im-plementation and deployment of new technologies. This approach will help to improve the level of technology acceptance among the users.

关键词： Telemedicine Diabetes mellitus Physicians Nurses

Effect of Thermo-Mechanical Treatment on Mechanical Properties and Microstructure of Fe-31Mn-4Si-2Al-Nb-Ti TWIP Steel

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Effect of Thermo-Mechanical Treatment on Mechanical Properti...

Evaluation of hydrogen effect on the fatigue crack growth behavior of medium-Mn steels via in-situ hydrogen plasma charging in an environmental scanning electron microscope

2011 International Conference on Advanced Materials Engineering(ICAME 2011)

作者： Davood Zamani abbas Najafizadeh Hossein monajati Gholam Reza razavi Department of Materials Science and Engineering Najafabad Branch Islamic Azad University Isfahan Iran Department of Materials Engineering Isfahan University of Technology Isfahan Iran

The effect of addition of Nb and Ti also thermomechanical treatment on mechanical properties and microstructure of a twinning induced plasticity（TWIP） steel have been *** results indicated that addition of Nb and Ti enhances strength also increasing cold rolling reduction has been increased *** ductility increased with increasing annealing temperature however strength *** centric limit of partial recrystallization regime,maximum increasing in work hardening capacity and also almost high yield strength has been ***,utilization of large cold rolling reduction and subsequently annealing treatment in the centric limit of partial recrystallization region was suggested as an effective method to obtain TWIP steel with an excellent combination of strength and ductility.

关键词： TWIP Steel Ti partial recrystallization cold Rolling annealing

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Journal of Materials Science & Technology 2021年第26期85卷 30-43页

作者： Di Wan Yan Ma Binhan Sun Seyed Mohammad Javad razavi Dong Wang Xu Lu Wenwen Song Department of Mechanical and Industrial Engineering Norwegian University of Science and TechnologyRichard Birkelands vei 2B7491TrondheimNorway Steel Institute(IEHK) RWTH Aachen UniversityIntzestraße 152072AachenGermany Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 140237DüsseldorfGermany

Fatigue crack growth(FCG)tests were conducted on a medium-Mn steel annealed at two intercritical annealing temperatures,resulting in different austenite(γ)to fe rrite(α)phase fractions and differentγ(meta-)*** in-situ hydrogen plasma charging was combined with in-situ cyclic loading in an environmental scanning electron microscope(ESEM).The in-situ hydrogen plasma cha rging increased the fatigue crack growth rate(FCGR)by up to two times in comparison with the reference tests in *** investigations showed a brittle-like crack growth or boundary cracking manner in the hydrogen environment while a ductile transgranular manner in *** both materials,the plastic deformation zone showed a reduced size along the hydrogen-influenced fracture path in comparison with that in *** difference in the hydrogen-assisted FCG of the medium-Mn steel with different microstructures was explained in terms of phase fraction,phase stability,yielding strength and hydrogen *** refined study can help to understand the FCG mechanism without or with hydrogen under in-situ hydrogen charging conditions and can provide some insights from the applications point of view.

关键词： Hydrogen embrittlement Fatigue crack growth(FCG) Electron channeling contrast imaging(ECCI) Medium-Mn steel Hydrogen plasma

Cluster decay half-lives using asymmetry dependent densities

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Chinese Physics C 2022年第4期46卷 131-140页

作者： V.Dehghani S.A.Alavi R.razavi A.Soylu F.Koyuncu Department of Physics University of Sistan and BaluchestanZahedanIran Physics Department Faculty of ScienceImam Hossein Comprehensive UniversityTehranIran Department of Physics Nigdeomer Halisdemir UniversityNigde 51240Turkey Program of Opticianry Golhisar Vocational School of Health ServicesBurdur Mehmet Akif Ersoy University15400GolhisarBurdurTurkey

By adopting different neutron and proton density distributions,cluster decay half-lives were investigated using double-folding potentials with constant and nuclear asymmetry dependent sets of nuclear density *** adopted asymmetry dependent sets of parameters were fitted based on microscopic calculations,and they were calculated based on the neutron skin/halo-type nuclei assumption and by employing experimental rms charge radii.A bulk agreement between theory and experiment was obtained for all sets of parameters using a calculated cluster preformation *** differences were observed between the skin and halo-type ***,the notable role of the asymmetry parameter was observed in the relatively large differences between the skin and skintype with zero thickness.

关键词： cluster decay double-folding charge radii density