Microstructure,martensitic transformation and shape memory effect of polycrystalline Cu-Al-Mn-Fe alloys

In this study, two Cu-Al-Mn-Fe polycrystalline alloys were prepared, and their microstructure, reversible martensitic transformation, mechanical properties and shape memory effects were investigated. The results show that the reversible martensitic transformation temperatures of the studied alloys are between room temperature and 373 K, which are suitable for practical applications. Two typed martensites of 18R and 2H coexist both in two alloys. The bcc β(FeAl) nanoparticles are Fe-rich, Mnrich and Cu-poor, whereas the martensite is Cu-rich, Fe-poor and Mn-poor. The size of nanoparticles ranges from tens to hundreds of nanometers. Full shape recovery property is displayed in Cu-12.9Al-4.5Mn-2.6Fe alloy all the time while applying different deformation from 5% to 8%. The maximum recoverable strain is up to 4.4% with a recovery rate of 100%.     

加热速度对Cu－Zn－Al－Mn淬火态合金马氏体逆相变的影响

用直流电阻法对Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ淬火态试样在不同加热速度下的马氏体逆相变进行了研究．结果表明，加热速度对Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ水淬及油淬试样的逆相变有较大的影响，尤其对水淬试样，加热速度慢到一定程度可以阻止马氏体逆相变的发生，或者使逆相变中出现反向过程，即ＤＯ３→ＭＩ８Ｒ转变．在慢速加热时，同时存在着马氏体时效及母相时效两种时效作用，加热速度越慢，这两种时效作用影响越大，从而使马氏体逆相变表现出对加热速度的敏感性．     

一种微合金化马氏体不锈钢的连续冷却转变研究

用膨胀法结合金相与硬度分析研究了一种新型水轮机叶片用V、N微合金化CrNiMo不锈钢的连续冷却转变行为,获得了该钢的连续冷却转变（CCT）曲线及不同冷却条件下的显微组织和硬度。结果表明,试验用钢的1、3、和温度分别为580℃、730℃、295℃和190℃,其贝氏体和铁素体分别在冷速小于0.5和0.2℃/s时出现,冷速在0.056~0.5℃/s之间时,硬度随着冷速的增大迅速增加,尔后随着冷速的增大,硬度缓慢升高。     

Effects of Annealing Temperature on the Electrical Conductivity and Mechanical Property of Cu-Te Alloys

The effects of annealing temperatre on the electrical conducitivity and mechanical property of Cu-Te alloys were studied via an AG-10TA electronic universal machine, an SB2230 digital electric bridge, SEM, EDS and XPS. The results show the electrical conductivity increases while the tensile strength fluctuates when the annealing temperature becomes higher because the recrystallization occurs during the annealing process, leading to the density of dislocation decreasing, grain size growing up, but the second phase precipitating sufficiently and simultaneously.     

基于人机交互的界面故障数据属性识别方法

为了提高故障数据识别精度,提出基于人机交互的界面故障数据属性识别方法.利用LCD显示与小键盘构成具备数据采集功能的人机交互模块采集界面故障数据,通过离群熵提取界面故障数据噪声并进行消噪处理,结合低通、高通滤波器重构界面故障数据信号,构建待选数据属性池,计算目标数据和待选数据之间的距离相似因子,从而实现界面故障数据属性识别.结果表明,该方法复杂度较低,识别复杂系数介于0.4~0.52之间,查全率可达到95%,识别精度约为91%,大大提升了设备界面故障数据识别性能.     

退火处理对La-Mg-Ni-Co合金电化学性能的影响

为了改善La-Mg-Ni-Co系贮氢电极合金的综合电化学性能，研究了退火处理对La0.7Mg0.3(Ni0.85Co0.15)3.4相结构和电化学性能的影响.在1 073 ～1 223 K下退火9 h制得样品，并进行了XRD分析以及恒电流充放电、线性极化和恒电位阶跃3种电化学测试.结果表明，铸态和退火态合金均由具有PuNi3结构的主相及少量杂相组成.退火态合金相的成分和结构均匀性得到明显改善，并具有较低的吸氢体积膨胀率.退火处理使合金的最大放电容量有所提高，循环稳定性得到明显改善.退火态合金放电容量的提高与合金中主相丰度的增大密切相关.合金循环稳定性的改善主要归结于退火态合金具有较低的吸氢体积膨胀率和较好的合金成分均匀性.     

Atomistic simulations of martensitic transformation processes for metastable FeMnCoCr high-entropy alloy

Non-equiatomic Fe Mn Co Cr high-entropy alloy(HEA), which exhibits a great potential to break the strength-ductility trade-off relationship, has drawn abundant attention from researchers in experiments. However, atomic simulations of such excellent alloys are limited due to the lack of proper interatomic potentials. In this work, the complete martensitic transformation of nonequiatomic HEA is reproduced via atomic simulations with a novel interatomic potential under EAM framework. The physical p...     

退火温度对FeCoNbVSiBCu合金高频性能的影响

研究了经不同温度退火后纳米晶合金(Fe0.5Co0.5)73.5Nb2V1Si13.5B9Cu1的磁化曲线及磁谱曲线.实验结果表明,(Fe0.5Co0.5)73.5Nb2V1Si1.5B9Cu1合金在460℃退火可获得良好的软磁性能.随退火温度的升高,纳米晶合金的畴壁钉扎场逐渐增加,初始磁导率降低,其截止使用频率却有明显提高.实验发现,经不同温度退火生成的纳米晶合金其在很宽的温度范围内基本保持不变,因此可以通过提高退火温度适当降低初始磁导率来提高纳米晶合金的截止使用频率范围.     

Microstructural evolution and tensile properties of low-carbon steel with martensitic microstructure during warm deforming and annealing

For preparing large-scale nano-grained and ultrafine-grained steel sheets by warm rolling and annealing,the effects of de- forming temperature on both the flow stress and the microstructure evolution of 09MnNiD steel with lath martensitic microstructure were studied by warm-compression test and transmission electron microscopy(TEM)observation.Thereafter,the steel with the lath martensitic structure was multi-pass warm-rolled and then annealed.TEM results indicate that nano-grained and ultrafine-grained steel sheets are formed by warm rolling at 400℃and annealing at 400-600℃.In comparison with the as-warm-rolled specimen,the tensile strength at room temperature changes a little when the rolled samples are annealed below 450℃,and the tensile strength is greatly lowered as the annealing temperature increases to above 550℃.     

Alter martensitic phase transformation kinetics by forming Ni-rich nanolayer in metastable austenitic steels

A 5 nm Ni-rich nanolayer has been introduced along nanoscale martensite/austenite phase boundaries(PBs) by one-step lowtemperature annealing treatment of cold-rolled meta-stable austenitic steels. Control experiments reveal that the martensitic phase transformation kinetics can be significantly altered by presence of the nanolayers. The growth of pre-existed martensites is substantially suppressed while the martensite nucleation in austenites is less affected, as revealed by a statistical investigation on the martensite size distribution under different tensile strains. Enhanced strength and excellent ductility have been achieved simultaneously in the annealed samples, demonstrating that PBs can be effectively engineered to achieve optimized mechanical properties.     

退火工艺对Mg-4Zn-1．5RE合金显微组织的影响

介绍了Mg-4Zn-1．5RE合金。实验利用小型轧机对挤压态Mg-4Zn-1．5RE合金进行多道次轧制,研究了轧制后合金板材经不同的退火工艺处理后其显微组织随退火温度和退火时间的变化情况．观察了合金中的第二相的TEM形貌并进行能谱分析。结果表明,该镁合金在常温下可进行多道次轧制,但每两道次之间进行300℃x30min的退火处理,总变形量可达到60％;轧制后的板材经再次退火后发生再结晶,合金中第二相为含有稀土元素的w相。     

Cooling rate effects on the structure and transformation behavior of Cu-Zn-Al shape memory alloys

Different fragments of a hot-rolled and homogenized Cu–Zn–Al shape memory alloy（SMA） were subjected to thermal cycling by means of a differential scanning calorimetric（DSC） device. During thermal cycling, heating was performed at the same constant rate of increasing temperature while cooling was carried out at different rates of decreasing temperature. For each cooling rate, the temperature decreased in the same thermal interval. During each cooling stage, an exothermic peak（maximum） was observed on the DSC thermogram. This peak was associated with forward martensitic transformation. The DSC thermograms were analyzed with PROTEUS software： the critical martensitic transformation start（Ms） and finish（Mf） temperatures were determined by means of integral and tangent methods, and the dissipated heat was evaluated by the area between the corresponding maximum plot and a sigmoid baseline. The effects of the increase in cooling rate, assessed from a calorimetric viewpoint, consisted in the augmentation of the exothermic peak and the delay of direct martensitic transformation. The latter had the tendency to move to lower critical transformation temperatures. The martensite plates changed in morphology by becoming more oriented and by an augmenting in surface relief, which corresponded with the increase in cooling rate as observed by scanning electron microscopy（SEM） and atomic force microscopy（AFM）.     

退火处理对Ti-Zr-Cu-Be块体非晶合金力学性能的影响

采用铜模铸造法制备了直径为2mm的Ti55-xZr10+xBe27.5Cu7.5(x=0,10,20)块体非晶合金,并对其进行等温退火处理.利用X射线衍射(XRD)、扫描电镜(SEM)、差氏扫描量热仪(DSC)及压缩试验等方法研究了非晶合金的相结构、显微组织和热稳定性,以及退火处理对其力学性能的影响.结果表明:该系列合金在553 K及583 K下保温长达5 h时间内依然表现为非晶态.退火处理后,Ti35Zr30Be27.5Cu7.5合金屈服强度、断裂强度均提到了提高,其中在583 K下保温1 h后屈服强度、断裂强度分别达到了1 921、2 169 MPa;其塑性由处理前的3.47%提高到了6.57%.Ti45Zr20Be27.5Cu7.5合金在退火后其力学性能变化不明显.Ti55Zr10Be27.5Cu7.5合金随着退火温度及保温时间的增加其屈服强度、断裂强度及塑性均明显降低.     

Effect of Cu doping and annealing treatment on the microstructure and magnetic properties of nanocrystalline single-phase Nd-Fe-B alloys

The effects of Cu addition and annealing treatment on the magnetic properties and microstructure of Nd12.3Fe81.7-xCuxB6 (x=0-1.2) ribbons melt-spun and annealed were systematically investigated by the methods of vibrating sample magnetometer (VSM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Optimum magnetic properties were achieved by annealing melt-spun Nd12.3Fe81.5Cu0.2B6 ribbons at 550°C for 15 min, which only contained Nd2Fe14B phase. The remanence, coercive force, and maximum ...     

终轧温度及轧后冷却速度对Q460C钢组织和相变的影响

在Gleebl-1500热应力／应变模拟实验机上热压缩模拟Q460C含铌钢的轧制过程,并控制终轧温度和轧后冷却速度。通过观察金相组织和膨胀曲线研究控轧控冷对Q460C钢组织和相变的影响,分析了轧制过程中可能诱导其裂纹产生的原因。结果表明,Q460C钢组织分布不均、控轧控冷工艺不合理均可能造成其裂纹的产生,提高终轧温度可促进相变提前发生,而在较高终轧温度下,轧后冷却速度对Q460C钢组织变化的影响很小。     

Influences of 2.5wt% Mn addition on the microstructure and mechanical properties of Cu-Al-Ni shape memory alloys

The influences of 2.5wt%Mn addition on the microstructure and mechanical properties of the Cu-11.9wt%Al-3.8wt%Ni shape memory alloy(SMA) were studied by means of scanning electron microscopy(SEM),transmission electron microscopy(TEM),and differential scanning calorimeter(DSC).The experimental results show that Mn addition influences considerably the austenite-martensite transformation temperatures and the kind of martensite in the Cu-Al-Ni alloy.The martensitic transformation changes from a mixedβ_1→β'_1...     

Reverse Transformation Behavior of TiNi Shape Memory Alloys Prestrained in the Parent Phase

1 IntroductionShape memory alloys (SMAs) prestrained at a tem-perature belowAs(the reverse martensitic transformationstartingtemperature) can generate a large stress or me-chanical energy when constrainedly heated at aboveAf(the reverse martensitic transformation finishing tempera-ture) ,therefore they are regarded as one of the most im-portant actuatorsinsmart composites[1-4].The relationshipbetweenthe prestrain level and the reversible martensitictransformationof TiNi SMAs has beenstudie…     

Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni_(50)Mn_(19)Fe_6Ga_(25) ribbons

~~Influence of stresses on martensitic transformation in ferromagnetic shape memory Ni_(50)Mn_(19)Fe_6Ga_(25) ribbons1. Ullakko, K., Huang, J. K., O'Handley, R. C. et al., Large magnetic-field-induced strains in Ni2MnGa single crystals, Appl. Phys. Lett., 1996, 69(13): 1966-1968. 2. James, R. D., Wuttig, M., Magnetostriciton of martensite, Philos. Mag., 1998, A 77: 1273-1275. 3. Wu, G. H., Yu, C. H., Meng, L. Q. et al., Giant magnetic-field-induced strains in H…     

肥液浓度对膜孔灌氮素运移转化的影响

为研究膜孔灌灌施条件下氮素运移转化分布规律,利用研制的膜孔点源入渗装置,在室内进行灌施条件下的氮素入渗试验,测试不同尿素肥液浓度下膜孔累积入渗量及土壤中氮素含量。结果表明：累积入渗量随灌施肥液浓度增大而增大;尿素肥液浓度对土壤中铵态氮及硝态氮含量在剖面分布影响较小,对其含量影响较大;转化生成的土壤铵态氮、硝态氮含量及土壤硝态氮分布范围随灌施肥液浓度增大而增大。     

烧结淬冷MnBi合金的相变和磁性

采用密封低温烧结再淬冷的方法制备了高纯度MnBi合金.利用差热分析仪(DTA)分析烧结过程中Mn-Bi的相变.利用X射线衍射仪(XRD)和振动样品磁强计(VSM)分析了烧结样品的物相和磁性.结果 表明:n(Bi)∶n(Mn)为1∶1.3,275℃下烧结20 h后淬冷可获得高纯度的低温相MnBi合金块体材料;温度为50～...