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Journal of Materials Science & Technology 2023年第29期160卷 34-45页

作者： Hao Li kuishan sun Xianglong Meng Wei Cai Liancheng Zhao School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Recently the isothermal martensitic transformation in shape memory alloys(SMAs)has been reported in many literatures,and several models have been proposed to interpret the isothermal and athermal ***,the underlying mechanisms remain inadequately *** this work,the isothermal transformation from B2 to B19 is confirmed in Ti-Ni-Cu-Co melt-spun ribbons at the temperature range between M s and M *** reaches a saturation point at every isothermal temperature T iso,and the saturation points correspond to the f−T curve at the cooling rate of 0.5 K/*** experimental results indicate that the isothermal accumulation of martensite is a relaxation process from the transient state to the thermoelastic balance one.A thermally activated kinetic model is developed in this study to characterize the isothermal and athermal *** model is able to estimate the evolution of martensite volume fraction under any temperature path T(t)and it agrees with the experimental results *** to the model,the effects of elastic energy,nucleation density,and activation energy on the kinetics are *** those,a small nucleation density n i as well as a large activation energy Qwill result in a significant isothermal *** this work,the slighter isothermal effects originate from the higher value of n *** for the non-stoichiometric SMAs,the higher value of Qis responsible for the accumula-tion of martensite at the isothermal ***,the present work provides a novel view from a kinetic model to understand the isothermal martensitic transformation in SMAs.

关键词： Shape memory alloys Thermoelastic martensitic transformation Kinetics Thermal activation

Revealing the interface structure of{111}typeⅠtwin in Ti-Ni-Hf shape memory alloy composite

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Journal of Materials Science & Technology 2022年第10期105卷 237-241页

作者： Xiaoyang Yi Bin sun kuishan sun Haizhen Wang Shangzhou Zhang Zhiyong Gao Xianglong Meng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China College of Nuclear Equipment and Nuclear EngineeringYantai UniversityYantai264005China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China College of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai264005China

*** Ti-Ni-Hf high temperature shape memory alloys have attracted great interests of many researchers due to the higher transformation temperatures and relatively lower cost[1,2].However,the recoverable strain is about 3%,which is signifcantly lower than the theoretical value[3-5].The functional performances of shape memory alloys are closely related to the substructure of twinned martensite and the structure of intervariant interface.

关键词： alloys alloy martensite

Tailoring the microstructure,martensitic transformation and strain recovery characteristics of Ti-Ta shape memory alloys by changing Hf content

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Journal of Materials Science & Technology 2021年第24期83卷 123-130页

作者： Xiaoyang Yi kuishan sun Jingjing Liu Xiaohang Zheng Xianglong Meng Zhiyong Gao Wei Cai College of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai264005China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China

In the present work,the microstructure features,martensitic transformation,mechanical properties and strain recovery characteristics of Ti-Ta based shape memory alloys were tailored by changing Hf *** singleα"martensite phase was dominated in Ti-Ta alloy with 2 at.%H *** Hf content exceeded2 at.%,βphase started to ***,the amount ofβphase gradually increased with Hf content *** martensitic transformation temperatures continuously decreased with the increased Hf content,which was attributed to the rising of valence electron ***,Hf addition improved the thermal cycling stability of Ti-Ta alloys due to the suppression ofω*** yield stress of Ti-Ta based alloys firstly decreased and then increased with Hf content *** addition,the completely recoverable strain of 4%can be obtained in Ti-Ta alloy with 6 at.%Hf as a consequence of the higher critical stress for dislocation ***,the Ti-Ta based alloy containing 8 at.%Hf had the superior superelasticity behavior with the fully recoverable strain of 2%at room temperature.

关键词： Ti-Ta high temperature shape memory alloy Microstructure Martensitic transformation Mechanical properties Strain recovery characteristics

Tailoring of microstructure and martensitic transformation of nanocrystalline Ti–Ni-Hf shape memory thin film

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Progress in Natural Science:Materials International 2021年第2期31卷 288-295页

作者： Xiaoyang Yi Haizhen Wang kuishan sun Bin sun Lengxi Wu Xianglong Meng Zhiyong Gao Wei Cai School of Materials Science and Engineering Harbin Institute of Technology Center of Testing and Analysis College of Materials Science and Chemical Engineering Harbin Engineering University College of Nuclear Equipment and Nuclear Engineering Yantai University

The amorphous Ti-Ni-Hf thin films with the specific compositions were prepared from single Ti-Ni-Hf alloy target by adjusting processing parameters of direct current magnetron sputtering deposition. Prior to the crystallization,a glass transition occurred in the present Ti-Ni-Hf thin films. The annealed Ti-Ni-Hf thin films were characterized by the nano-crystalline. With the annealing temperature increasing, the grain size firstly increased and then decreased owing to the presence of(Ti,Hf)Ni precipitate. Two endothermic and exothermic peaks corresponding to B19’■B2 martensitic transformation in heating and cooling curves were observed for the Ti-Ni-Hf thin films with the lower annealing temperature and shorter annealing time, which was closely related to the inhomogeneous composition. However, the Ti-Ni-Hf thin films annealed at higher annealing temperature and longer annealing time showed the single stage B19’■B2 martensitic transformation. In addition, the martensitic transformation temperatures firstly increased and then decreased with the annealing temperatures rising.

关键词： High temperature shape memory alloy Ti–Ni-Hf thin Film Crystallization Microstructure Martensitic transformation

Mechanisms of two-stage martensitic transformation in Ti-Ni-Hf alloy powder

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Progress in Natural Science:Materials International 2021年第5期31卷 749-754页

作者： Zhongli Liu Xinxin Feng Xiaoyang Yi kuishan sun Haizhen Wang Zhiyong Gao Xianglong Meng College of Nuclear Equipment and Nuclear Engineering Yantai University School of Materials Science and Engineering Harbin Institute of Technology

The Ti-Ni-Hf shape memory alloy powders were prepared by plasma rotating electrode *** the powders were featured with the perfect sphericity and smooth ***,the grain size was refined in the Ti-Ni-Hf alloy powders due to the rapid cooling rate during plasma rotating electrode *** was found that the Ti-NiHf alloy powders had the typical self-accommodation configuration including spear-like,mosaic-like and lath-like *** twins,such as (001) compound twin,(011) type I twin as well as{111}type I twin,were observed in Ti-Ni-Hf alloy *** from the bulk Ti-Ni-Hf alloy,two-stage transformation corresponding to B2■B19’martensitic transformation was detected in the as-received Ti-Ni-Hf alloy *** addition,the martensitic transformation behaviors were closely related to the annealing *** Ti-NiHf alloy powders with low annealing temperature of 500~°C still exhibited two-stage martensitic transformation,while two-stage martensitic transformation changed into single martensitic transformation in the Ti-Ni-Hf alloy powders with the higher annealing temperature of 900~°*** finally the possible mechanisms for the evolution of martensitic transformation behaviors were discussed.

关键词： Ti-Ni-Hf alloy Powders Shape memory shape PREP Martensitic transformation Microstructure

Tuning microstructure, transformation behavior, mechanical/functional properties of Ti-V-Al shape memory alloy by doping quaternary rare earth Y

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Progress in Natural Science:Materials International 2021年第2期31卷 296-302页

作者： Xiaoyang Yi kuishan sun Haizhen Wang Yifu Gong Xianglong Meng Zhiyong Gao Hua Zhang Wei Cai College of Nuclear Equipment and Nuclear Engineering Yantai University Institute for Advanced Studies in Precision Materials Yantai University School of Materials Science and Engineering Harbin Institute of Technology

The microstructure features, martensitic transformation behavior and mechanical/functional properties of Ti–V–Al alloy were tailored by changing rare element Y content in the present investigation. The results showed that Y doping resulted in the grain refinement and formation of Y-rich phase mainly distributing along grain boundary in Ti–V–Al alloys. The martensitic transformation temperatures of Ti–V–Al alloys slightly increased due to the variation of matrix composition induced by the presence of Y-rich phase. The mechanical and functional properties of Ti–V–Al alloys doped moderate Y addition were significantly improved, which can be ascribed to grain refinement, solution strengthening and precipitation strengthening. The 1.0 at.%Y-doped Ti–V–Al alloy exhibited the highest ultimate tensile stress of 912 MPa and largest elongation of 17.68%. In addition, it was found that the maximum recoverable strain of 5.42% can be obtained in Ti–V–Al alloy with adding 1.0 at.%Y,under the pre-strain of 6% condition, which is enhanced by approximate 0.6% than that of Ti–V–Al alloy without Y addition.

关键词： Light weight shape memory alloy Ti–V–Al alloy Microstructure Phase transformation Mechanical properties

Effect of thermo-mechanical treatment on Ti–Ta-Hf high temperature shape memory alloy

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Progress in Natural Science:Materials International 2021年第5期31卷 779-782页

作者： Jun Li Xiaoyang Yi Haizhen Wang kuishan sun Jingjing Liu Xianglong Meng Zhiyong Gao College of Mechanical and Electrical Engineering Northeast Forestry University School of Materials Science and Engineering Harbin Institute of Technology College of Nuclear Equipment and Nuclear Engineering Yantai University

The microstructure, martensitic transformation and mechanical/functional properties of Ti–Ta-Hf alloys with various thermo-mechanical treatments were investigated. The results reveal that the hot-rolling could refine the grain size and introduce a certain number of defects, resulting in the disappearance of martensitic *** as-casted and solution treated Ti–Ta-Hf alloys were composed of α’’ martensite phase and smaller volume of βphase. In contrast, the grain size of solution treated Ti–Ta-Hf alloy was slightly less than that of as-casted Ti–Ta-Hf alloy. This should be responsible to the higher yield stress and superior strain recovery characteristics for solution treated Ti–Ta-Hf alloy. The yield stress for the dislocation slip and the maximum recoverable strain of solution treated Ti–Ta-Hf alloy were 723 MPa and 5.06%, respectively.

关键词： High temperature shape memory alloy Hot-rolled Microstructure Martensitic transformation Shape memory effect

Divergent responses of runoff to climate change in the upper basins of the Third Pole dominated by westerlies and monsoon

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Science China Earth Sciences 2024年第8期67卷 2592-2614页

作者： Qikai sun Fengge SU He sun State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100101China

The diverse climates,distribution of snow and glaciers,and geographic locations directly affect the runoff response to climate change in the upper basins of the Third *** present,a comprehensive analysis of runoff variations and their distinct responses to climate change in the westerlies-and monsoon-dominated upper basins is still *** study comprehensively analyzed annual runoff variations in westerlies-dominated basins(the upper basins of the Aksu(UAKS),Syr Darya(USRD),Yarkant(UYK),Hotan(UHT),Amu Darya(UAMD),and Indus(UI))and monsoon-dominated basins(the upper basins of the Yangtze(UYA),Yellow(UYE),Lancang(ULC),Nujiang(UNJ),and Yarlung Zangbo(UYZ))of the Third Pole from 1961 *** multi-source meteorological data and large-scale circulation factors,this study investigated the divergent responses of runoff in the upper basins to climate change,and explored the large-scale circulation mechanisms underlying runoff variations in these upper *** results showed that:(1)The annual runoff in the majority of upper basins(except for the UYE and UYZ)exhibited an increasing trend,and the annual runoff in the UAKS,UYK,and UI showed a significant increasing trend from1961 to *** annual runoff in the upper basins of the Third Pole changed abruptly from decreasing to increasing between the 1980s and 2000s,with the exception of the UYE.(2)The runoff in the monsoon-dominated upper basins has been controlled primarily by changes in precipitation over the past 55 *** contrast,the runoff in the westerlies-dominated upper basins exhibited three distinct long-term responses to climate change:temperature-dominated(UYK and UHT),precipitation-dominated(USRD and UAMD),and the combined influence of precipitation and temperature(UAKS and UI).Since the 1960s,the sensitivity of runoff to warm season temperature changes in the most westerlies-dominated upper basins has decreased,while the response of runoff to precipitation changes has intensified.(3)The stud

关键词： Upper basins of the Third Pole Climate change Westerlies and monsoon Runoff variations Large-scale circulation factors

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Fossil Equidae in the Linxia Basin with Biostratigraphic and Paleozoogeographic Significance

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 1-9页

作者： sun Boyang Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijing 100044China

The Linxia Basin is characterized by an abundance of Cenozoic sediments,that contain exceptionally rich fossil *** are abundant in the Linxia Basin,the fossil record of equids in this region including 16 species that represent 10 *** comparison to other classic late Cenozoic areas in China,the Linxia Basin stands out,because the fauna and chronological data accompanying Linxia equids render them remarkably useful for *** anchitheriines in the region,such as Anchitherium and Sinohippus,represent early equids that appeared in the late stages of the middle and late Miocene,*** the equines,most species of Chinese hipparions have been identified in the Linxia Basin and some species of the genera Hipparion and Hippotherium have FAD records for ***,Equus eisenmannae is one of the earliest known species of Equus in the Old World and is well-represented at the Longdan *** species with precise geohistorical distributions can serve as standards for high-resolution chronological units within this *** at the eastern margin of the Tibetan Plateau and subject to considerable uplift,the Linxia Basin has served as a biogeographic transition area for equids throughout the late Cenozoic.

关键词： Equidae Cenozoic biostratigraphy paleozoogeography Linxia Basin

Achieving simultaneously high conversion and high selectivity for light olefins directly producing from syngas

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Science China Chemistry 2024年第3期67卷 753-754页

作者： Yuhan sun Shanxi Research Institute Huairou Research LaboratoryTaiyuan 030032China Institute of Carbon Neutrality ShanghaiTech UniversityShanghai 201210China

The activity and selectivity are two primary indexes of a successful catalyst for chemical reactions. However,achieving a high activity and a high selectivity simultaneously is a long-standing challenge in catalysis, the socalled activity-selectivity trade-off. In the article recently published in Science, a research team led by Prof.

关键词： selectivity simultaneous catalysis