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Episodes 2005年第3期28卷 177-186页

作者： j. Brilha C. Andrade A. Azeredo f.j.A.S. Barriga m. Cachāo2 H. Couto P.P. Cunha j.A. Crispim P. Dantas L. V. Duarte m. C freitas H.m. Granja m.H. Henriques P. Henriques L. Lopes j. madeira j.m.x. matos.f. noronha j. Pais j. Pifarra m.m. Ramalho j.m.R.S. Relvas A. Ribeiro A. Santos V.f.Santos P. Terrinha University of minho University of Lisbon National Natural History museum University of Porto University of Coimbra Portuguese Speleological Society INETInovacāo University of évora New University of Lisbon League for Nature Protection University of Algarve

This work constitutes the first contribution for the systematisation of geological heritage knowledge in Portugal, following the international recommendations for the characterisation of geological heritage （IUGS, ProGEO）. The application of the ProGEO methodology has resulted in the creation of fourteen frameworks with international relevance, established by consensus among the Portuguese geological community. The description of each category in this paper is not exhaustive and only the most relevant scientific settings are presented. The following are the three key outcomes of this work： i） At a national level, the most important geosites are identified, indicating where geoconservation efforts should be prioritised based on scientific justification; ii） At a regional level, conditions have been developed to foster dialogue with Spanish colleagues in order to create Iberian frameworks; iii） At an international level, it is now possible to integrate Portuguese geosites into the global inventories promoted by IUGS, UNESCO, and ProGEO.

关键词：葡萄牙欧洲地质条件地质图地形特征

Phase Selection in Solidi?cation of Undercooled Co–B Alloys

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journal of materials Science & Technology 2017年第4期33卷 352-358页

作者： x.x.Wei W.xu j.L.Kang m.ferry j.f.Li State Key Laboratory of metal matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240.China Australian Research Council Centre of Excellence for Design in Light metals School of Materials Science and EngineeringThe University of New South WalesSydneyNSW 2052Australia

A series Co-（18.5–20.7） at.% B melts encompassing the eutectic composition（Co81.5B18.5） were solidified at different degrees of undercooling. It is found that the metastable Co23B6 phase solidifies as a substitute for the stable Co3 B phase in the alloy melts undercooled above a critical undercooling value of -60 *** Co23B6 and α-Co phases make up a metastable eutectic. The corresponding eutectic composition and temperature are Co80.4B19.6 and 1343 K, respectively. On exposure of the metastable Co23B6 phase at a given temperature above 1208 K, it does not decompose even after several hours. But it transforms by a eutectoid reaction to α-Co ＋ Co3 B at lower temperature.

关键词： Undercooling Rapid solidi?cation metastable phase diagram Structure evolution

ON THE mONTE CARLO SImULATION Of NORmAL GRAIN GROWTH

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Acta metallurgica Sinica(English Letters) 2008年第4期21卷 282-288页

作者： Y.T. Liu x.j. Guan x.m. Shen x.f. ma L.j. Wang School of materials Science and Engineering Shandong University Jinan 250061 China

The microstructures and their kinetics of normal grain growth are simulated using different monte Carlo （mC） algorithms. Compared with the relative figures and the theoretical normal grain growth exponents of n =0.5, the effects of some factors of mC algorithm, i.e. the lattice types, the methods of selecting lattice sites, and the neighbors selection for energy calculations, on the simulation results of grain growth are studied. Two methods of regression were compared, and the three-parameter nonlinear regression is much more suitable for fitting the grain growth kinetics. A better model with appropriate factors included triangular lattice, the attempted site randomly selected, and the first and second nearest neighbors for energy calculations is obtained.

关键词： Grain growth microstructure monte Carlo method Computer simulation Grain growth kinetics Nonlinear regression

A pathway to improve low-cycle fatigue life of face-centered cubic metals via grain boundary engineering

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journal of materials Science & Technology 2022年第18期113卷 82-89页

作者： x.j.Guan Z.P.jia S.m.Liang f.Shi x.W.Li Department of materials Physics and Chemistry School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Key Laboratory for Anisotropy and Texture of materials Ministry of EducationNortheastern UniversityShenyang 110819China

To probe a pathway to improve the low-cycle fatigue life of face-centered cubic(fCC)metals via grain boundary engineering(GBE),the tension-tension fatigue tests were carried out on the non-GBE and GBE Cu-16 at.%Al alloys at relatively high stress *** results indicate that the cyclic strain localiza-tion and cracking at grain boundaries(GBs)can be effectively suppressed,especially at increased stress amplitude,by an appropriate GBE treatment that can result in a higher resistance to GB cracking and a greater capability of compatible ***,the sensitivity of fatigue life to stress amplitude can be weakened by GBE,and the low-cycle fatigue life of Cu-16 at.%Al alloys is thus distinctly improved.

关键词： Cu-Al alloy Grain boundary engineering fatigue life Crack nucleation Stress amplitude

Ab initio molecular dynamics study on the local structures in Ce_(70)Al_(30) and La_(70)Al_(30) metallic glasses

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Chinese Physics B 2018年第5期27卷 405-411页

作者： f x Li j B Kong m Z Li Department of Physics Beijing Key Laboratory of Opto-electronic Functional Materials ＆ Micro-nano Devices Renmin University of China Beijing 100872 China

Ab initio molecular dynamics simulations were performed to investigate the effect of similar elements on the shortto medium-range atomic packing features in Ce70Al30 and La70Al30 glass-forming alloys. 4 f electrons of Ce element in Ce70Al30 alloy were properly treated in electronic calculations. The local atomic structures in both alloys are qualitatively similar. However, the local environments of Al atoms in Ce70Al30 alloy show fluctuation with temperature in the cooling process, which could result from 4 f electrons of Ce elements. Surprisingly, the medium-range atomic packing features of Al atoms in both mGs are quite different, although Ce and La elements are similar. These findings are useful for understanding the enhanced glass-forming ability by similar element substitution in RE-based mGs from a medium-range structure perspective.

关键词： rare earth-based metallic glasses medium-range order molecular dynamics simulation

Semi-solid processing of hypereutectic A390 alloys using novel rheoforming process

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1743-1748页

作者： m.TEBIB j.B.mORIN f.A jERSCH x.GRANT CHEN Université du Québec à Chicoutimi cole polytechnique de montréal

The feasibility of semi solid processing of hypereutectic A390 alloys using a novel rheoforming process was investigated. A combination of the swirl enthalpy equilibration device （SEED） process, isothermal holding using insulation and addition of solid alloy during swirling was introduced as a novel method to improve the processability of semi solid slurry. The effects of isothermal holding and the addition of solid alloy on the temperature gradient between the centre and the wall and on the formation of a（Al） particles were examined. In additional tests, phosphorus and strontium were added to the molten metal to refine the primary and eutectic silicon structure to facilitate semi solid processing. The results show that the combination of the SEED process with two additional processing steps can produce semi-solid A390 alloys that can be rheoprocessed. The microstructure reveals an adequate amount of non-dendritic a（Al） globules surrounded by liquid, which greatly improves the processability of semi-solid slurry.

关键词： semi-solid forming rheoforming process hypereutectic A390 alloys microstructure

mICROSTRUCTURES AND PROPERTIES Of RECIPROCATINGLY ExTRUDED mg-6.4Zn-1.1Y ALLOYS

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Acta metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： Z.m. Zhang C.j. xu x.f. Guo School of materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral mg3 YZn6 quasicrystalline phase can be produced in mg-Zn- Y system alloys when a proper amount of Zn and Y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast mg-6.4Zn-1.1 Y alloy are analyzed. The microstructure of the as-cast mg-6.4Zn-1.1 Y alloy consists of the α-mg solid solution, icosahedral mg3YZn6 quasicrystal, and mg3 Y2Zn3 and mgZn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, mg3 Y2 Zn3 and mgZn2 phases dissolved into the matrix, whereas, mg3 YZn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 mPa, 258.2 mPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast mg-6.4Zn-1.1 Y alloy, particularly for elongation. The high performance of the mg-6.4Zn-1.1 Y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion mg-Zn- Y alloy Icosahedral quasicrystal

mICROSTRUCTURE Of mg-6.4Zn-1.1Y ALLOY fABRICATED BY RAPID SOLIDIfICATION AND RECIPROCATING ExTRUSION

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Acta metallurgica Sinica(English Letters) 2008年第1期21卷 30-36页

作者： Z.m. Zhang C.j. xu x.f. Guo School of materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified mg-6.4Zn-1.1 Y magnesium alloy with a thickness of 50-60μm were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEm, and the constituent phases were identified by xRD. Phase transformation and its onset temperature were determined by differential thermal analyzer （DTA）. The analysis result shows that rapid solidification for *** alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in α-mg solute solution, and impede the formation of mg3 Y2Zn3 and mgZn2 compounds, and thus help the icosahedral mg3 YZn6 quasicrystal formed directly from the melt. The microstructure of the flakes consists of the α-mg solid solution and icosahedral mg3 YZn6 quasicrystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more mg3 YZn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases： α- magnesium solid solution as matrix and fine icosahedral mg3 YZn6 quasicrystal which disperses uniformly in the matrix.

关键词： magnesium alloy Rapid solidification Reciprocating extrusion Quasicrystal

NiTi laser textured implants with improved in vivo osseointegration:An experimental study in rats

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journal of materials Science & Technology 2022年第19期114卷 120-130页

作者： m.m.Costa A.miranda f.Bartolomeu O.Carvalho S.matos G.miranda f.S.Silva Center for microElectromechanical Systems(CmEmS-Uminho) University of MinhoCampus de AzurémGuimarães 4800-058Portugal Life and Health Sciences Research Institute(ICVS) School of MedicineUniversity of MinhoCampus de GualtarBraga 4710-057Portugal ICVS/3B’s-PT Government Associate Laboratory Braga/GuimarãesPortugal Center for Innovation and Research in Oral Sciences(CIROS) Faculty of MedicineUniversity of CoimbraFMUCPortugal CICECO Aveiro Institute of MaterialsDepartment of Materials and Ceramic EngineeringUniversity of AveiroAveiro 3810-193Portugal

Laser surface texturing is a versatile approach for manufacturing implants with suitable surfaces for *** work explores the use of laser to fabricate NiTi textured implants,testing two dif-ferent groove-based *** performance was evaluated in vivo through implantation in Sprague Dawley rats’femur,being then analyzed after 4 and 12 weeks of ***-out experiments and histological characterization allowed to assess bone-implant bond and osseointegration and to compare the laser textured solutions with non-textured *** showed that,at 4 weeks of implantation,mainly immature woven bone was present whilst at 12 weeks a more mature bone had ***-sidering the largest implantation time(12 weeks),results showed extraction forces considerably higher for textured implants(G2 and G3).moreover,when comparing G2 and G3,it was found that G2(having the highest textured surface area)displayed the maximum extraction force among all groups,with an increase of 212%when compared to non-textured implants(G1).These results prove that the design and manufacturing technology are effective to promote an im-proved bone-implant bond,aiming the development of orthopedic implants.

关键词： NiTi Laser surface texturing In vivo studies Osseointegration Implants

Interface Shape and marangoni Effect Around aBubble Within the Thermal Boundary Layer

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journal of Thermal Science 1998年第1期7卷 54-60页

作者： x.f.Peng j.m.Ochterbeck 等 ThermalEngineeringDepartment TsinghuaUniversityBeijing100084China mechanicalEngineeringDepartment C

The characteristics of a vapor bubble within the thermal boundary layer were theoretically *** physical models accounting for the variation of ioterfacial tension and nuid density with tempera-ture were proposed to investigate bubble interfaCe aspects and the fluid flow around the bubble. The analyses demonstrated that the variation in interfacial tension results in variations in the liquid-vapor interface shape and bubble dynamics, which may play a significant role in the departure process of a vapor bubble from a heated wall surface. Increasing temperature gradients in the boundary layer and the gravitational field induce a contact line contraction and correspondingly promotes bubble depar-ture. The simulation of liquid now around the bubble shows that natural convection dominates the flow for earth conditions; however, the thermocapillary forces provide the principal catalyst for bubble departure in a microgravity environment. The results indicate that both the vapor bubble contraction and the marangoni flow may increase the heat transfer around the vapor bubble and may cause the bubble to mov away from the heating surface, further increasing heat transfer.

关键词： interfacial phenomenon marangoni effect bubble boiling