不同Cu含量的TiNiCu形状记忆合金薄膜的组织与相变

利用TEM、XRD、DSC测试方法,首次系统地研究了直流磁控溅射制备的3种不同Cu含量的TiNiCu形状记忆合金薄膜的退火组织和加热与冷却过程中发生的相变.结果表明:退火后的薄膜获得了形状记忆性能;随着薄膜中Cu含量的增加,薄膜的退火组织出现差异,相变滞后明显变小,相变温区变窄;使获得快速响应的形状记忆合金薄膜成为可能.     

Influence of temperature rate on transitory internal friction during reverse martensitic transformation for Ti50Ni27Cu23 alloy

Internal friction (IF) spectra during reverse martensitic transformation from 35 to 135°C at different temperature rates of 0.5,0.75,and 1°C/min for Ti50Ni27Cu23 shape memory alloy (SMA) samples were measured with a dynamic mechanical analyzer,respectively.The IF spectra were characterized by IF peak increasing progressively and peak shifting toward high temperature with an increase in temperature rate.An iterative approach was used to calculate the precise intrinsic and approximate transitory IF contributions to the normal IF spectrum.The quantitatively analyzed results indicate that the transitory IF of this alloy is nonlinearly dependent on the temperature rate and obeys a power law with a power coefficient of 0.55.The predicted and experimental IF spectra at different temperature rates of 0.75 and 1°C/min agree well with each other,respectively.     

Analysis of the internal friction spectra during martensitic transformation by a new temperature rate method

The internal friction spectra of a martensitic transformation obtained as a function of temperature with , consists of three different contributions: transitory, phase transition, and intrinsic. In order to get a more quantitative information from these internal friction spectra, such as the volume fraction of transformed material, it is necessary to separate the spectra in their different contributions. This paper proposes a new method which allows to analyse the IF spectra. The new procedure is based on the strong dependence of the transitory term on the temperature rate. Thus, the separation of the three different contributions to the IF is completed starting from several IF spectra carried out at different temperature rates. Using this method it is possible to check the validity of the different models proposed in the literature for the explanation of the transitory term. Along with the presentation of the method, its application to a thermoelastic Cu–Al–Ni shape memory alloy is shown.     

TiNiCu形状记忆合金薄带研究进展

TiNiCu形状记忆合金薄带凭借其窄相变滞后、优异的形状记忆效应与超弹性、良好的热循环稳定性成为一种很有前途的微驱动器材料。本文全面阐述了国内外在TiNiCu薄带研究方面的最新进展,主要包括晶化行为、显微组织、马氏体相变行为、形状记忆效应与超弹性,重点介绍了热处理工艺-显微组织-性能之间的内在联系,探讨了TiNiCu薄带今后的研究重点     

Temperature memory effect of Ti50Ni30Cu20 (at.%) alloy

After the reverse thermal induced martensitic transformation process of shape memory alloy is arrested at a temperature between the reverse transformation start and finish temperatures (A_s and A_f), and then cooled to a temperature below M_f, a kinetic stop will occur in the next heat flow curve during the heating process. The kinetic stop is closely related to the arrested temperature. This phenomenon is called temperature memory effect (TME). TME of Ti₅₀Ni₃₀Cu₂₀ (at.%) shape memory alloy with phase transformation between B2 austenite and B19 martensite has been investigated by differential scanning calorimeter in this paper. The results indicate that TME of Ti₅₀Ni₃₀Cu₂₀ alloy only exists in the heating process.     

Internal friction of Ti–Ni alloys

The low-frequency internal friction and the modulus have been measured on Ti–Ni alloys of varying compositions, from Ni 49.89 to 51.0 at. %, in a wide range of temperatures covering the martensitic and the reverse transformations. The effect of heat treatment on the internal friction has also been investigated. The internal friction shows a sharp peak around the martensitic transformation and/or the formation of pre-martensitic state ‘R-phase’. The height and temperature of the peak depend strongly on the composition and on the heat treatment. Corresponding to the internal friction peak a remarkable depression of the modulus has been observed. At temperatures lower than 250 K two types of temperature dependences were observed; one is a step-type that changes slowly with temperature, and the other is a peak-type around 200 K. An annealing at 873 K has enhanced the low-temperature internal friction, while the solution heat treatment at 1273 K has appreciably decreased it. In all cases the damping of the parent phase is very low; the internal friction is lower than 10·10⁻⁴. The electrical resistivity and the thermoelectric power have been measured.     

Phase transformation behavior of a TiNiCu shape memory alloy electrolytically charged with hydrogen

The transformation behavior of a TiNiCu shape memory alloy electrolyticaUy charged with hydrogen was investigated by means of different scanning calorimetry (DSC), optical microscope and X-ray diffraction (XRD). The results showed that inter- and inner-granular hydrides formed after charging with hydrogen, and the hydrides suppressed martensitic transformation. The electrolyticaUy charged hydrogen can be easily released by heat treatment and the transformation occurred again, which was verified by the DSC and XRD experiments.     

热机械训练影响TiNiCu记忆合金DSC曲线特征的研究

利用示差扫描量热法(DSC)研究了加热伸长、冷却收缩和加热收缩、冷却伸长2种TiNiCu双向记忆效应弹簧训练过程中相变特征。研究结果表明，训练前升温时，DSC曲线表现出吸热峰由多个小峰组成，随着训练次数的增加，峰的个数减少，具有稳定双向记忆效应的试样中，升温时只出现1个锐利的峰。这是因为在训练过程中引入特定取向的位错，产生一定的应力场，使得马氏体变体的取向比较一致，相变点基本相同所导致。并由于位错的引入，引起相变点As和Af下降。     

Microstructures and transformation characteristics of thin films of TiNiCu shape memory alloy

Both sputtering conditions and crystallizing temperatures have great influence on the microstructures and phase transformation characteristics for TislNi44Cus. By means of the resistance-temperature measurement, X-ray diffraction and atomic fore microscopic study, the results indicate that the transformation temperatures of the thin films increase and the “rock candy“ martensitic relief is more easily obtained with promoting the sputtering Ar pressure, sputtering power, orcrystallizing temperature. However, when sputtering Ar pressure, sputtering power, or crystallizing temperature are lower, a kind of “chrysanthemum“ relief, which is related with Ti-rich GP zones, is much easier to be observed. The reason is that during crystallization process, both of the inherent compressive stresses introduced under the condition of higher sputteringpressure or higher crystallizing temperature are helpful to the transition from GP zones to Ti2(NiCu) precipitates and the increase of the transformation temperatures. The addition of copper to substitute for 5 96 nickel in mole fraction can reduce the transformation hvsteresis width to about 10 - 15 ℃.     

Effect of heat treatment on the transformation behavior and temperature memory effect in TiNiCu wires

The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed that with increasing annealing temperature and annealing time, the phase transformation temperatures of TiNiCu wires were shifted to higher temperatures in the heating and cooling process. It was also found that incomplete thermal cycles, upon heating the TiNiCu wires, which were arrested at a temperature between the start and finish tem-peratures of the reverse martensite transformation, could induce a kinetic stop in the next complete thermal cycle. The kinetic stop tempera-ture was closely related to the previous arrested temperature. This phenomenon was defined as the temperature memory effect. The result of this study was consistent with the previous report on the phenomenon obtained using the differential scanning calorimetry method, indicating that temperature memory effect was a common phenomenon in shape memory alloys.     

Ni49.8Ti50.2合金马氏体逆相变的瞬态内耗与频率间关系的定量分析

采用动态力学分析仪测定了Ni49.8Ti50.2形状记忆合金在不同振动频率下的内耗-温度曲线,利用迭代法定量分析了内耗-温度曲线,将其分为本征和瞬态两个分量,定量研究了瞬态内耗与频率间的关系.研究表明该合金的内耗值随着频率的增加而降低.根据所确定的理论模型由某个频率下的瞬态内耗-温度曲线可预测其他频率下的瞬态内耗-温度曲线.     

Strain amplitude-dependent internal friction of as-cast high damping magnesium alloy during cyclic vibration

An investigation on strain amplitude-dependent internal friction (IF) of an as-cast high damping Mg-7 wt% Ni alloy was carried out. In the range of our tested strain amplitudes, whether the strain amplitude is increasing or decreasing, the strain amplitude-dependent IF curve can be divided into two stages: one is the strain amplitude weakly dependent part and the other is the strain amplitude strongly dependent part. However, after several cyclic vibrations, the IF values measured during the strain amplitude increasing are smaller than those obtained during the strain amplitude decreasing. The phenomenon is also observed at 100 ℃. Partial dislocations generate a short-range slip under the cyclic stress to be responsible for it.     

Effect of Pd additions on phase stability and hydrogen-induced internal friction of Ti34Zr11Cu47Ni8 glassy alloys

The effects of additions of Pd below 10 at.% on the stability and hydrogen-induced internal friction behavior of Ti₃₄Zr₁₁Cu₄₇Ni₈ glassy alloys have been investigated. Thermal analyses indicate that the supercooled liquid region decreases distinctly with increasing Pd content. It was found that internal friction peak temperatures of Ti₃₄Zr₁₁Cu₄₇Ni₈–Pd hydrogenated glassy alloys (HGAs) in the hydrogen content range below approximately 30 at.% H were higher than those of the original Ti₃₄Zr₁₁Cu₄₇Ni₈ HGAs, especially at hydrogen contents below 10 at.% H. It was also found that the internal friction peaks of Ti₃₄Zr₁₁Cu₄₇Ni₈–Pd HGAs increased with increasing hydrogen content below 15 at.% H, after which they tended to saturate. These results are in contrast to the effects of Si addition as previously reported. The effects of Pd are discussed from the viewpoint of the interstitial site distribution for hydrogen and local atomic structure of the glassy alloy.     

Cu–13.2Al–3Ni (wt%) single crystal studied by isothermal mechanical spectroscopy

The internal friction has been measured under isothermal conditions over a large frequency range (10⁻³ to 40 Hz) in a Cu–13.2Al–3Ni (wt.%) single crystal at temperatures between 293 and 473 K, including the martensitic transformation. On one hand, atypical behavior was revealed in the martensitic state. Indeed, the damping level measured at low frequency, below Ms, is much more important when it is determined under cooling conditions than on heating. On the other hand, a high damping level was observed in a very narrow temperature range during direct transformation. This last effect was ascribed to the nucleation process of the martensite, whereas a freeze in interface motion could be responsible for the thermal asymmetric behavior.     

形状记忆合金微型阀的研制

本文阐述了形状合金的特性,形状记忆合金作为驱动元件,具有结构紧凑、功率重量比大、易控制等优点,大大推动了微型机器人的发展。本课题利用形状记忆合金作为驱动元件,开发了微型气动阀,实现了与微机器人主体的集成。     

铁含量对Al—Si—Fe合金微观组织及内耗性能的影响

采用快速冷凝－粉末包套挤压工艺制备了含铁量分别为1．2％和3．5％的Al-Si-Fe合金。研究了这两合金在挤压和退火状态下的微观组织特征和内耗行为。解决了Fe含量及其析出相、热处理状态等对内耗的影响,提出了该合金在系在60－250℃温度范围产生内耗峰的机制。     

A chemical sensor based on internal friction

This study demonstrates the detection of and differentiation between airborne chemicals using high resolution internal friction and frequency measurements. In essence, we determine the loss (1/Q) per unit mass of analyte absorbed by a chemoselective polymer deposited on a resonator. We report the selectivity and sensitivity of this sensing technique for AT-cut quartz resonators coated with two different chemoselective polymers exposed to each of six different analytes. We also used spectra subtraction to extract the mechanical response changes of the thin film polymer coating from that of the coated resonators both with and without an analyte present.     

2219铝合金搅拌摩擦焊接头晶间腐蚀分析

采用晶间腐蚀试验研究了2219铝合金搅拌摩擦焊接头的晶间腐蚀行为,结合接头显微组织、微观硬度、腐蚀形貌及腐蚀深度,分析母材与焊核区的差异,并对接头晶间腐蚀机理进行了初步的探讨.结果表明,焊核区为细小的等轴晶组织,且接头上表面焊核区的晶粒要大于下表面焊核区的晶粒;母材区硬度最高,下表面焊核区硬度最低;焊核区的耐蚀性优于母材,且上表面焊核区耐蚀性优于下表面焊核区,母材最大腐蚀深度为145.9 μm,上表面焊核区及下表面焊核区最大腐蚀深度为46.3 μm和84.1 μm.     

轧制对Mg-3Cu-1Mn合金温度阻尼峰的影响(英文)

经过变形量4.7%的单道次室温轧制变形,Mg-3Cu-1Mn合金的一次温度—阻尼谱出现了3个明显的阻尼峰;在二次温度—阻尼谱中,3个阻尼峰均发生变化,特别是第3阻尼峰P3受到抑制,变得非常不明显。对各阻尼峰峰温处淬火样品进行金相、XRD、EBSD等实验,研究轧制对Mg-3Cu-1Mn合金温度—阻尼峰的影响。结果表明:在一次温度—阻尼谱中的P3峰处出现织构增强、孪晶急剧消失的现象;轧制变形后,3个温度—阻尼峰依次为位错阻尼峰、晶界阻尼峰和孪晶引发的再结晶阻尼峰;另外,随着拉伸孪晶的消失,室温轧制态Mg-3Cu-1Mn合金的应变阻尼性能大幅度恢复,高应变下接近均匀化退火态Mg-3Cu-1Mn的应变阻尼性能。这说明拉伸孪晶对Mg-3Cu-1Mn合金应变阻尼性能有不利的影响。