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Microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with different prestrain levels

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Journal of Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.h.Zhang h.Li Z.W.Yang X.Liu Q.F.Gu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of high-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(sma)is a promising material in the aerospace field due to its wide transformation *** application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to ***-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of sma ***,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)sma subjected to vari-ous prestrain levels are still *** this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(M_(s)+30℃)were *** results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.Whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,*** stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb *** stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SIMVs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced ***{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density of{114}austenite twins form in the specimen with a larger prestrain of 16%.With increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then ***ε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%*** increase ofε_(re)^(T)can be attributed to the formation of new SIMVs,the further growth of existing SIMVs,and the recoverable(001)compound *** the decrease ofε_(re)^(T)is mainly associated with the irrecoverable strain by{20−1}martensite *** effe

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy Wide transformation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

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对cN0喉及下咽癌患者进行Ⅳ区和Ⅴ区的颈清扫是否合理

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临床耳鼻咽喉头颈外科杂志 2008年第21期22卷 998-1001页

作者： hSEYN KATILMIS SEDAT ZTRKCAN smaLZDEMR BLGE TUNA ISIL ADADAN GVENC YILMAZ ZKUL 王彦君孔维佳 Department of Otorhinolaryngology and head and Neck Surgery Atatürk Research and Training Hospital Ministry of Health Department of Otorhinolaryngology and head and Neck Surgery Borcka State HospitalMinistry of Health 华中科技大学同济医学院附属协和医院耳鼻咽喉科武汉430022

目的:为了制定恰当的颈清扫治疗方案,对cN0喉癌和下咽癌患者的淋巴结累及区域和复发率作一评价。方法:回顾性分析接受局限性颈淋巴结清除术的238例cN0患者,至少随访24个月,并对局部复发进行评估。结果:Ⅳ区的隐匿性淋巴结转移率是3.4%;... 详细信息

目的:为了制定恰当的颈清扫治疗方案,对cN0喉癌和下咽癌患者的淋巴结累及区域和复发率作一评价。方法:回顾性分析接受局限性颈淋巴结清除术的238例cN0患者,至少随访24个月,并对局部复发进行评估。结果:Ⅳ区的隐匿性淋巴结转移率是3.4%;其中单独转移至Ⅳ区的是1.5%。我们观察发现颈部的局部复发率是5.6%,在Ⅴ区没有发现淋巴结转移和局部复发。结论:当术中颈淋巴结冷冻切片为阴性,对cN0患者可合理性做出Ⅱ、Ⅲ区清扫术,Ⅳ区部分清扫术及对侧颈部淋巴结清扫术,得出结论:Ⅴ区颈清扫术是没有必要的,除非在Ⅴ区有明显的转移灶。

关键词：喉肿瘤下咽肿瘤颈淋巴清扫术颈淋巴结淋巴道转移

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Microstructural evolution and superelastic properties of ultrafine-graine d NiTi-base d shape memory alloy via sintering of amorphous ribbon precursor

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Journal of Materials Science & Technology 2023年第7期138卷 80-92页

作者： W.S.Cai h.Z.Lu h.Z.Li Z.Liu h.B.Ke W.h.Wang C.Yang National Engineering Research Center of Near-net-shape Forming for Metallic Materials Guangdong Provincial Key Laboratory for Processing and Forming of Advanced Metallic MaterialsSouth China University of TechnologyGuangzhou 510640China Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China

NiTi-based shape memory alloys(smas)are considered as cutting-edge intelligent functional ***,it remains a great challenge to obtain ultrafine-grained(UFGed)bulk materials with mm-scale size as well as outstanding superelastic ***,UFGed bulk Ti_(35)Zr_(15)Ni_(35)Cu_(15)NiTi-based sma is successfully prepared via spark plasma sintering of amorphous ribbon precursor at different sintering temperatures,and microstructural evolution and superelastic properties are symmetrically *** is found that its grain size ranges from UFG to micro-grain with increased sintering temperature regard-less of the predominant B2 matrix in all bulk ***,the orientation relationships between B2 matrix and nano-scale fcc(Ti,Zr)_(2)Ni precipitate evolve from coherent to ***,the UFGed samples exhibit perfect superelasticity with the high recoverable strain of∼5.8%,the stable recov-ery rate above 99%,and the great critical stress inducing martensitic transformation higher than 1 GPa,far superior to the corresponding ones of suction-cast micro-grained TiZrNiCu ***,the perfect superelasticity is attributed to the good resistance to dislocation slip or grain boundary slip by residual nano-scale amorphous phase or secondary phase of coherent and semi-coherent fcc(Ti,Zr)_(2)Ni *** addition,the gentle superelastic plateau is associated to the favorable transfer stress and the strong ability to accommodate dislocation movement,which is generated by the coherent interface between nano-scale fcc(Ti,Zr)_(2)Ni and UFGed B2 *** results suggest that spark plasma sintering of amorphous alloy precursor is a feasible route to obtaining excellent superelasticity in NiTi-based smas.

关键词： Shape memory alloy Amorphous alloy Microstructure Superelasticity

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Calculation of electric field–temperature (E, T) phase diagram of a ferroelectric liquid crystal near the sma–SmC_α~* transition

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Chinese Physics B 2018年第3期27卷 444-450页

作者： F Trabelsi h Dhaouadi O Riahi T Othman Universite de Tunis El-Manar Faculte des Sciences de TunisLaboratoire de physique de la matiere molle et de modelisation electromagnetique(LP3ME)Campus Universitaire Farhat Hached 2092 Tunis Tunisie

In this work we perform a theoretical calculation in order to reconstitute the （E-T） phase diagram of a chiral smectic liquid crystal in the vicinity of the sma-SmCα＊ transition. This reconstruction is carried out on the basis of a thermo-dynamic calculation of the slope of the curve joining the SmC＊ domain and the unwound SmC＊. An empiric correction of the mean field term of Landau De-Gennes development is necessary to accomplish this reconstruction. Thereafter, an experimental validation is performed to verify our calculations.

关键词： field-temperature phase diagram liquid orystal

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局地大气扩散试验研究

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环境科学学报 1985年第1期 96-104页

作者：俎铁林国家气象局气象科学研究院

本文主要介绍昆明附近某地的一次扩散试验.结果表明,水平扩散参数对不同稳定度分辨得较好.导出的垂直扩散参数能反映出地面不同粗糙度的差别,所得最大落地点浓度点距离及稀释因子比采用P-G参数提级办法算出的结果更符合实测值,并指明平... 详细信息

本文主要介绍昆明附近某地的一次扩散试验.结果表明,水平扩散参数对不同稳定度分辨得较好.导出的垂直扩散参数能反映出地面不同粗糙度的差别,所得最大落地点浓度点距离及稀释因子比采用P-G参数提级办法算出的结果更符合实测值,并指明平均气流的上升或下沉对落地浓度的影响不可忽视.在有风条件下,导出了扩散参数随取样时间变化的指数q值.在小风条件下,对稀释效果起主要作用的是水平风方位变化的范围及垂直气流的方向和强弱,而垂直稳定度所起的作用往往是间接的.在模式选用上,小风和静风应加以区别.静风时可忽略模式中各速度分量,小风和静风的界线约在0.6m/s左右.

关键词：扩散参数垂直气流结构参数稳定度浓度分布分布(力学) 正态分布 Gauss 分布平均风速取样时间风向变化横截大气扩散气体扩散

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An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memory effect in shape memory alloys

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Frontiers of Structural and Civil Engineering 2015年第4期9卷 466-477页

作者： S. hAShEMI h. AhMADIAN S. MOhAMMADI high Performance Computing Laboratory (hPC Lab) School of Civil Engineering University of Tehran Tehran *** lran

Thermo-mechanical coupling in shape memory alloys is a very complicated phenomenon. The heat generation/absorption during forward/reverse transformation can lead to temperature-dependent variation of its mechanical behavior in the forms of superelasticity and shape memory effect. however, unlike the usual assumption, slow loading rate cannot guarantee an isothermal process. A two-dimensional thermo-mechanically coupled algorithm is proposed based on the original model of Lagoudas to efficiently model both superelasticity and shape memory effects and the influence of various strain rates, aspect ratios and boundary conditions. To implement the coupled model into a finite element code, a numerical staggered algorithm is employed. A number of simulations are performed to verify the proposed approach with available experimental and numerical data and to assess its efficiency in solving complex sma problems.

关键词： shape memory alloy thermo-mechanical coupling superplasticity shape memory effect

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Simultaneous enhancement of mechanical and shape memory properties by heat-treatment homogenization of Ti_(2)Ni precipitates in TiNi shape memory alloy fabricated by selective laser melting

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Journal of Materials Science & Technology 2022年第6期101卷 205-216页

作者： h.Z.Lu L.h.Liu C.Yang X.Luo C.h.Song Z.Wang J.Wang Y.D.Su Y.F.Ding L.C.Zhang Y.Y.Li National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640China Musculoskeletal Oncology Department Sun Yat-Sen University Cancer CenterGuangzhouGuangdong ProvinceChina Shenyang Aircraft Design and Research Institute Shenyang 110035China Guangdong huayi Plumbing Fittings Industry Co. Ltd.Kaiping 529321China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia

The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(smas) fabricated using selective laser melting(SLM) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)sma fabricated using SLM. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant sma exhibited an ultrahigh tensile strength of 880 ± 13 MPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni smas fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni smas and will accelerate the wider application of smas.

关键词： Shape memory alloy Selective laser melting heat treatment Mechanical properties Shape memory properties

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Numerical and Experimental Research on Modular Oscillating Fin

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Journal of Bionic Engineering 2008年第1期5卷 13-23页

作者： Yong-hua Zhang Yan Song Jie Yang K. h. Low Department of Precision Machinery and Precision Instrumentation University of Science and Technology of China Hefei 230026 P. R. China School of Mechanical and Aerospace Engineering Nanyang Technological University 639798 Singapore

Fishes are famous for their ability to position themselves accurately even in turbulent flows. This ability is the result of the coordinated movement of fins which extend from the body. We have embarked on a research program designed to develop an agile and high efficient biologically inspired robotic fish based on the performance of hybrid mechanical fms. To accomplish this goal, a mechanical ray-like fin actuated by Shape Memory Alloy （sma） is developed, which can realize both oscillatory locomotion and undulatory locomotion. We first give a brief introduction on the mechanical structure of our fin and then carry out theoretic analysis on force generation. Detailed information of these theoretical results is later revealed by Computational huid Dynamic （CFD）, and is final validated by experiments. This robotic fin has potential application as a propulsor for future underwater vehicles in addition to being a valuable scientific instrument.

关键词： oscillating fin Shape Memory Alloy (sma) Computational huid Dynamics (CFD) modular design

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Social Scale and Collective Computation:Does Information Processing Limit Rate of Growth in Scale?

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Journal of Social Computing 2022年第1期3卷 1-17页

作者： Timothy A.Kohler Darcy Bird David h.Wolpert the Department of Anthropology Washington State UniversityPullmanWA 99164-4910USA Santa Fe Institute Santa FeNM 87501USA Crow Canyon Archaeological Center CortezCO 81321USA Cluster of Excellence ROOTS Christian-Albrechts-UniversitätKiel 24118Germany. Max Planck Institute for the Science of human history Jena 07745Germany the Santa Fe Institute Santa FeNM 87501USA Center for Biosocial Complex Systems Arizona State UniversityTempeAZ 85281USA Complexity Science hub Vienna 1080Austria

Collective computation is the process by which groups store and share information to arrive at decisions for collective *** societies engage in effective collective computation depends partly on their *** arrangements and technologies that work for small-and mid-scale societies are inadequate for dealing effectively with the much larger communication loads that societies face during the growth in scale that is a hallmark of the *** important bottleneck for growth may be the development of systems for persistent recording of information(writing),and perhaps also the abstraction of money for generalizing exchange *** on Shin et al.,we identify a Scale Threshold to be crossed before societies can develop such systems,and an Information Threshold which,once crossed,allows more or less unlimited growth in *** introduce several additional articles in this special issue that elaborate or evaluate this Thresholds Model for particular types of societies or times and places in the world.

关键词： social evolution thresholds model information processing writing demographic scale collective computation

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Rosmarinic acid attenuates hepatic fibrogenesis via suppression of hepatic stellate cell activation/proliferation and induction of apoptosis

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Asian Pacific Journal of Tropical Medicine 2017年第5期10卷 423-432页

作者： Naglaa M.El-Lakkany Walaa h.El-Maadawy Sayed h.Seif el-Din Olfat A.hammam Salwa h.Mohamed Shahira M.Ezzat Marwa M.Safar Samira Saleh Department of Pharmacology Theodor Bilharz Research InstituteWarak El-HadarImbaba P.O.Box 30Giza 12411Egypt Department of Pathology Theodor Bilharz Research InstituteWarak El-HadarImbaba P.O.Box 30Giza 12411Egypt Department of Immunology Theodor Bilharz Research InstituteWarak El-HadarImbaba P.O.Box 30Giza 12411Egypt Department of Pharmacognosy Faculty of PharmacyCairo UniversityCairo 11562Egypt Department of Pharmacology and Toxicology Faculty of PharmacyCairo UniversityCairo 11562Egypt

Objective:To investigate the antifibrotic role of rosmarinic acid(RA),a natural polyphenolic compound,on hSCs activation/proliferation and apoptosis in vitro and in vivo. Methods:The impact of RA on stellate cell line(hSC-T6) proliferation,activation and apoptosis was assessed along with its safety on primary hepatocytes. In vivo,rats were divided into:(i) normal;(ii) thioacetamide(TAA)-intoxicated rats for 12 weeks;(iii) TAA+silymarin or(iv) TAA+RA. At the end of experiment,liver functions,oxidative stress,inflammatory and profibrogenic markers,tissue inhibitor metalloproteinases type-1(TIMP-1) and hydroxyproline(hP) levels were evaluated. Additionally,liver histopathology and immunohistochemical examinations of alpha-smooth muscle actin(α-sma),caspase-3 and proliferation cellular nuclear antigen(PCNA) were determined. Results:RA exhibited anti-proliferative effects on cultured hSCs in a time and concentration dependent manner showing an IC50 of 276 μg/mL and 171 μg/mL for 24 h and 48 h,respectively,with morphological reversion of activated stellate cell morphology to quiescent form. It significantly improved ALT,AST,oxidative stress markers and reduced TIMP-1,hP levels,inflammatory markers and fibrosis score(S1 vs S4). Furthermore,reduction in α-sma plus elevation in caspase-3 expressions of hSCs in vitro and in vivo associated with an inhibition in proliferation of damaged hepatocytes were recorded. Conclusions:RA impeded the progression of liver fibrosis through inhibition of hSCs activation/proliferation and induction of apoptosis with preservation of hepatic architecture.

关键词： hepatic fibrosis hepatic stellate cells Rosmarinic acid Apoptosis Proliferation Profibrogenic markers

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