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The Gondwana Orogeny in northern North Patagonian Massif:Evidences from the Caita Có granite, La se?a and Pangaré mylonites,Argentina

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Geoscience Frontiers 2016年第4期7卷 621-638页

作者： Daniel A.Gregori Bernhardt saini-Eidukat Leonardo Benedini Leonardo strazzere Mercedes Barros José Kostadinoff Cátedra de Geología Argentina Departamento de Geología Universidad Nacional del Sur and INGEOSUR Department of Geosciences North Dakota State University Cátedra de Campos Gravitacionales Departamento de Física Universidad Nacional del Sur

structural analyses in the northern part of the North Patagonia Massif, in the foliated Caita Co granite and in La sefia and Pangare mylonites, indicate that the pluton was intruded as a sheet-like body into an opening pull-apart structure during the Gondwana Orogeny. Geochronological studies in the massif indicate a first, lower to middle Permian stage of regional deformation, related to movements during indentation tectonics, with emplacement of foliated granites in the western and central areas of the North Patagonian Massif. Between the upper Permian and lower Triassic, evidence indicates emplacement of undeformed granitic bodies in the central part of the North Patagonian Massif. A second pulse of deformation between the middle and upper Triassic is related to the emplacement of the Caita CO granite, the development of mylonitic belts, and the opening of the Los Menucos Basin. During this pulse of deformation, compression direction was from the eastern quadrant.

关键词： Gondwana Orogeny Northern Patagonia Foliated granite Mylonites Argentina

Phase Formation and Magnetic Properties of Nanocomposite Nd-Fe-B Adjusted by small Amount of Dy and Co

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Journal of Rare Earths 2004年第Z2期22卷 89-94页

作者： T s Jang T W Lim h s Aum D h Lee M B Kim Division of Materials and Chemical Engineering Sun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Mechanical EngineeringSun Moon University 100 Kalsan LiTangjung MyonAsan CityChoongnam 336-708Korea Division of Materials and Chemical EngineeringSun Moon UniversityKorea Division of Materials and Chemical EngineeringSun Moon UniversityKorea

In order to improve and stabilize the magnetic properties of nanocomposite Nd2Fe14B/α-Fe magnetic alloys by a compositional adjustment, small amount of Dy and/or Co was added to Nd9Fe84B7 alloys. DTA analysis on the amorphous of the alloys took place as the soft magnetic phases were crystallized, and then the hard magnetic Nd2Fe14B was precipitated from them. While α-Fe and a metastable 1:7 (TbCu7-type) phase were formed simultaneously in Dy and Co-free alloys, they were crystallized separately at different temperatures after Dy or Co was added. This phase separation occurred more clearly in the Dy-treated alloys and the other soft magnetic phase Fe3B was also stabilized by Dy and/or Co. The 1: 7 phase that was stabilized by Dy and/or Co was not eliminated at 700 ℃, decreasing magnetic properties of the alloys. It was eventually disappeared above 725 ℃, but Fe3B was not eliminated even at 750 ℃ when Dy was added more than 0.5 at% or Co was added more than 2.0 at%. Amount of Nd2Fe14B in the alloys tended to increase as Dy addition increased,whereas Co addition did not lead to any appreciable change in the ratio of α-Fe and Nd2Fe14B. Moreover, Dy addition apparently increased coercivity of an alloy while Co addition had a beneficial effect on remanence. The grains in the Dytreated alloys were usually finer than those in the Co-treated alloys. The grain size of both α-Fe and Nd2Fe14B in the alloys exhibiting mr ≥ 0.72 was in the range of 20 ～ 40 nm or even larger 50 nm, which is larger than the theoretical optimum size ( ～ 10 nm). Typical magnetic properties obtained from a Nd7.5Dy1.5Fe82.5Co1.5B7 alloy annealed for 12 min at 725 ℃were ihc=4.85 kOe, Br= 11.32 kG, (Bh)max = 15.73 MGOe, and mr=0.73.

关键词： nanocomposite Nd-Fe-B magnetic properties remanence coercivity

TENsILE CREEP DEFORMATION AND DAMAGE BEhAVIOR IN A NICKEL-BAsE sUPERALLOY AT 900℃

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Acta Metallurgica sinica(English Letters) 2004年第4期17卷 606-611页

作者： h.C.Yu s.s.Xie h.C.Yang Beijing Institute of Aeronautical Materials Beijing 100095 ChinaR & D Center Baosteel Co. Ltd. Shanghai 201900 ChinaCollege of Materials and Metallurgy Northeastern University Shenyang 110004 China

The tensile creep deformation and damage evolution in a Ni-base superalloy at 900℃/170MPa were investigated. At the first creep stage, abnormal creep occured due to the resolution of fine particles, and the deformation initiated from grain boundary areas. It is evident that nearly all of the dislocations were in γ matrix channels in form of dislocation pairs and the dislocations were impeded at γ/γ' interfaces, thus the dislocation networks developed deformation. At the steady creep stage, impeded dislocations atγ/γ' interfaces climbed over γ' phases by diffusion-dominant mechanism. At the last creep stage, voids were formed around carbides at grain boundary which leaded to accumulated damage and caused creep rate accelerated. With the dislocation networks being broken, the voids connected and grew into micro-cracks gradually. Finally the cracks propagated along grain boundary area and resulted in failure.

关键词： creep deformation and damage dislocation microstructure su-peralloy

Mode filtering based on ponderomotive force nonlinearity in a plasma filled rectangular waveguide

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Plasma science and Technology 2017年第10期19卷 70-74页

作者： h sOBhANI h R sABOUhI s FEILI E DADAR Young Researchers and Elite Club Qom Branch Islamic Azad University Department of Electrical Engineering Hormoz Branch Islamic Azad University Department of Physics Shahid Bahonar University Faculty of Economic Mofid University

here a new scheme for mode filtering is proposed. Based on the ponderomotive force effect,propagation of the microwave dual-mode through a plasma-filled metallic rectangular waveguide is investigated. To excite the TE_（20） mode in a rectangular waveguide, the existence of fundamental modes is unavoidable. To filter the destructive mode（TE_（10））, the waveguide is filled with a collisional plasma. Based on the coupling effect, the energy of this destructive TE_（10） mode is transferred to the TE_（20） mode. The proposed structure acts like a mode convertor. The TE_（10） mode become more attenuated and instead the TE_（20） mode is amplified. The plasma filled rectangular waveguide acts as a mode filtering tool.

关键词： mode filtering mode convertor collisional plasma ponderomotive force

Effects of Austempering and Martempering Processes on Amount of Retained Austenite in Cr-Mo steels (FMU-226) Used in Mill Liner

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Journal of Iron and steel Research International 2010年第2期17卷 53-58页

作者： M h shaeri h saghafian s G shabestari school of Metallurgy and Materials Engineering Iran University of Science and Technology

The presence of retained austenite gives rise to deterioration of the wear resistance and fracture strength of Cr-Mo steels in many cases. Thus, the effects of heat treatments including direct quenching, martempering, and austempering on the retained austenite existing in the microstrueture of these steels were investigated. specimens were austenized at 950 ℃ followed by direct quenching using compressed and still air. The specimens were also isothermally quenched in salt bath at 200 and 300 ℃ for 2, 8, 30, and 120min. Microstructures of the specimens were studied using optical microscope （traditional black and white etching as well as color etching）, scanning electron microscope （sEM）, microhardness tester, and X-ray diffraction （XRD）. The results showed that the lowest amount of retained austenite in the microstructure was obtained in the specimens quenched isothermally at 300 ℃ for 120 min.

关键词： Cr-Mo steel austempering martempering retained austenite microstructure

structural, electronic, elastic, and thermal properties of CaNih3 perovskite obtained from first-principles calculations

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Chinese Physics B 2018年第3期27卷 384-390页

作者： s Benlamari h Bendjeddou R Boulechfar sAmara Korba h Meradji R Ahmed s Ghemid R Khenata s Bin Omran Laboratoire LPR Departement de Physique Faculté des Sciences Université Badji Mokhtar Annaba Algeria Department of Physics Faculty of Science Universiti Teknologi Malaysia UTM Skudai 81310 Johor Malaysia Laboratoire de Physique Quantique et de Modelisation Mathematique de la Matiere (LPQ3M) Universite de Mascara-29000-Algeria Department of Physics and Astronomy College of Science King Sand University P.O. Box 2455 Riyadh 11451 Saudi Arabia

A theoretical study of the structural, elastic, electronic, mechanical, and thermal properties of the perovskite-type hydride CaNih3 is presented. This study is carded out via first-principles full potential （FP） linearized augmented plane wave plus local orbital （LAPW＋lo） method designed within the density functional theory （DFT）. To treat the exchange-correlation energy/potential for the total energy calculations, the local density approximation （LDA） of Perdew-Wang （PW） and the generalized gradient approximation （GGA） of Perdew-Burke-Ernzerhof （PBE） are used. The three independent elastic constants （C11, C12, and C44） are calculated from the direct computation of the stresses generated by small strains. Besides, we report the variation of the elastic constants as a function of pressure as well. From the calculated elastic constants, the mechanical character of CaNih3 is predicted. Pertaining to the thermal properties, the Debye temperature is estimated from the average sound velocity. To further comprehend this compound, the quasi-harmonic Debye model is used to analyze the thermal properties. From the calculations, we find that the obtained results of the lattice constant （ao）, bulk modulus （Bo）, and its pressure derivative （B0′） are in good agreement with the available theoretical as well as experimental results. similarly, the obtained electronic band structure demonstrates the metallic character of this perovskite-type hydride.

关键词： perovskite-type hydrides elastic constants hydrogen storage materials

Low-temperature green synthesis of boron carbide using aloe vera

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Chinese Physics B 2018年第10期27卷 578-583页

作者： h V sarithaDevi M s swapna G Ambadas s sankararaman Department of Optoelectronics and Department of Nanoscience and Nanotechnology University of Kerala Kariavattom Thiruvananthapuram-695581 Kerala India Government Victoria College Palakkad Kerala India

The unique structural and physical properties of boron carbide, which make it suitable for a wide range of applications,demands the development of low-cost and green synthesis method. In the present work, the commonly available leaves of aloe vera are hydrothermally treated to form the carbon precursor for the synthesis of boron carbide. The morphological characterization reveals the porous nature of the precursor turning into a tubular structure upon boron carbide *** structural characterization by x-ray diffraction and other spectroscopic techniques such as Fourier transform infrared,Raman, photoluminescence and uv-visible near-infrared spectroscopy confirm the formation of boron carbide. The thermogravimetric analysis of the sample is found to exhibit good thermal stability above 500 °C. When the sample is annealed to 600 °C, boron carbide with phase purity is obtained, which is confirmed through XRD and FTIR analyses. The optical emission properties of the sample are studied through CIE plot and power spectrum. Compared with other natural precursors for boron carbide, the aloe vera is found to give a good yield above 50%.

关键词： aloe vera boric acid boron carbide hydrothermal method

Friction-stir welding and processing of Ti-6Al-4V titanium alloy:A review

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Journal of Materials science & Technology 2018年第1期34卷 58-72页

作者： s.Mironov Y.s.sato h.Kokawa Department of Materials Processing Graduate School of Engineering Tohoku University

In this work, the current understanding and development of fliction-stir welding and processing of Ti- 6Al-4V alloy are briefly reviewed. The critical issues of these processes are addressed, including welding tool materials and design, tool wea,, processing temperature, material flow, processing window and residual stresses. A particular emphasis is given to microstructural aspects and microstructure-properties relationship. Potential engineering applications are highlighted.

关键词： Ti-6Al-4V titanium alloy Friction-stir welding Friction-stir processing Microstructure Properties

Anisotropy in dynamic recrystallization behavior of AZ31 magnesium alloy

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Journal of Magnesium and Alloys 2022年第12期10卷 3470-3484页

作者： s.M.Fatemi s.Kheyrabadi h.Paul Department of Metallurgy and Materials Engineering Shahid Rajaee Teacher Training University136-16785 TehranIran Institute of Metallurgy and Materials science Polish Academy of Sciences(PAS)25 Reymonta Street30-059 KrakowPoland

Deformation behavior as well as microstructural evolutions of a rolled AZ31 magnesium alloy with and without pre-existing extension twins were studied using compression tests which performed along different orientations at a temperature range of 25–350 ℃. The results implied that the initial texture not only influence the evolution of flow stress, but also change the size and fraction of recrystallized *** contrast to samples parallel to rolling and transverse directions, compression along normal direction resulted in a respectful softening at 150 ℃. The largest size and fraction of new grains at 250 ℃ were recorded after deformation along rolling direction, while the maximum flow softening was observed during deformation along normal direction. The anisotropy in microstructural evolutions was still retained at 350 ℃. Pre-existing twins could reduce the anisotropy of material in respect of flow stress as well as DRX progression, where TD sample showed the lowest DRX fraction at 250 ℃. Quaternion misorientation data obtained from EBsD analysis of pretwinned material implied that initial texture could not significantly influence final texture. A different misorientation distribution was realized after deformation of pretwinned material along ND and RD directions.

关键词： slip Recrystallization Grain size Growth Twin