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承受各种循环加载的TiNi形状记忆合金的超弹性变形行为 总被引:6,自引:0,他引:6
TiNi形状记忆合金由于其优良的机械性能、抗腐蚀能力和生物适应性得到广泛的使用。超弹性是TiNi形状记忆合金重要的力学性能之一。本文通过实验研究了不同加载速率和不同实验温度下承受完全循环加载以及部分加载卸载的TiNi形状记忆合金超弹性变形行为。分析了循环变形期间马氏体相变应力和弹性模量变化的特性。研究表明在完全循环加载过程中,由于残余应变的存在,马氏体相变应力随循环增加而减小。马氏体相变应力的变化量(即残余应力)与残余应变成线形关系。对于受过循环变形的机械训练的TiNi形状记忆合金,研究了部分加载和卸载情况下其超弹性变形,分析了相变开始与结束的应力特性。 相似文献
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简述了由于马氏体相变而出现的新型合金,主要有:形状记忆合金,超弹性合金,超塑性合金,减振合金及马氏体的增强增韧现象。 相似文献
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采用考虑塑性的超弹性材料模型和基于损伤塑性的准脆性材料模型,建立了三维单胞有限元模型,模拟了形状记忆合金颗粒增韧大块金属玻璃基复合材料的单调拉伸行为。讨论了形状记忆合金的力学参数、体积分数、界面厚度和界面材料参数对金属玻璃增韧效果的影响。结果表明:提高形状记忆合金的相变应变和马氏体塑性屈服应力将显著提高形状记忆合金颗粒增韧大块金属玻璃基复合材料的拉伸失效应变;形状记忆合金弹性模量超过50.0GPa、马氏体塑性屈服应力超过1.8GPa后,复合材料的拉伸失效应变变化不大。能同时兼顾失效应变和失效应力的形状记忆合金体积分数为15%左右。复合材料界面弹性模量和界面屈服应力的增加将提高复合材料的失效应力,但对失效应变影响不大;复合材料界面厚度的增加在提高失效应变的同时,也降低了复合材料的失效应力。 相似文献
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《中国材料进展》2016,(11)
Cu基形状记忆合金以其良好的形状记忆性能、优秀的导电导热性能、相变温度可调范围宽以及价格低廉等诸多优点,成为具有重要发展前景的一类形状记忆合金。但普通多晶组织Cu基形状记忆合金在应用时存在塑性差、易发生晶界开裂、疲劳寿命短、马氏体相变临界应力低等问题,严重制约了其应用范围,通过合理的组织设计可有效解决这些问题。综述了近年来高超弹性、高马氏体相变临界应力Cu基形状记忆合金组织设计方面的研究进展。研究发现,按照获得具有高相变应变的晶粒取向、获得大的晶粒尺度、获得平直的低能晶界等组织设计原则制备的竹节晶组织和柱状晶组织Cu基形状记忆合金的超弹性可达到7%以上。再经热处理析出贝氏体强化相后,可获得超弹性大于5%,马氏体相变临界应力大于650 MPa的优秀性能。 相似文献
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《中国材料进展》2016,(8)
形状记忆合金因具有形状记忆效应和超弹性等奇异的功能特性而受到广泛关注。但是,受限于一级马氏体相变的原理性制约,形状记忆合金的超弹性行为长期以来存在着能量耗散大的难题,并因此降低了材料的精密控制、疲劳性能和能量转化效率等,成为这类材料在高性能领域使用的瓶颈之一。从相变形核的角度综述了相关降低形状记忆合金超弹性能量耗散的研究工作,指出了通过降低材料相变能垒进而降低超弹性能量耗散的两个可行方案:(1)弱化自发晶格畸变量;(2)引入空间不均匀性。现有的分子动力学模拟发现纳米尺度的形状记忆合金由于其奇异的核-壳结构而同时满足以上两个解决方案,从而使得块体材料中强烈的一级马氏体相变转变为纳米尺度下的连续相变,导致材料出现奇异的零滞后的超弹性行为。这一理论也得到了近期实验的支持,从而为设计具有窄滞后超弹性行为的形状记忆合金提供了新思路与新方法。 相似文献
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《材料导报》2020,(14)
为充分发挥超弹性SMA的减振特性,奠定应用理论基础,对SMA丝进行了力学性能试验研究,探讨了循环训练次数、应变幅值和应变速率对SMA滞回性能的影响。基于SMA丝力学性能测试结果,在广义粘塑性框架下,对Graesser宏观唯象本构模型进行了拓展。新模型考虑了马氏体正/逆相变过程中特征参量的差异以及大应变幅值下的马氏体硬化特性,并通过引入的内变量演化方程,描述了应变幅值和应变速率对超弹性SMA滞回性能的影响;通过Matlab/Simulink模块对超弹性SMA滞回曲线进行了模拟,并将预测结果和试验结果进行了对比。结果表明:所建立的应变幅值-应变速率相关型SMA宏观唯象本构模型可较为精确地描述SMA在应力诱发相变过程中的超弹性力学行为,同时可反映应变速率和应变幅值对SMA滞回性能的影响。 相似文献
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本文简要介绍了形状记忆合金中的热弹性马氏体转变、相变伪弹性和形状记忆效应。目前镍钛合金和铜基合金已被广泛应用,如在医疗和自动控制技术中。在智能机器人的研制中形状记忆合金具有主要作用。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献
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Kyo-Hong CHOI Kwon-Koo CHO Gyu-Bong CHO Hyo-Jun AHN Ki-Won KIM Yoo-Young KIM 《材料科学与工程学报》2007,25(6):886-891
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD. 相似文献
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Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously. 相似文献