Fe/Ru界面对多层膜磁性的影响

采用高分辨透射电镜结合振动样品磁强计研究了Fe/Ru多层膜,对不同层厚的Fe/Ru多层膜的界面结构及其对磁性能的影响进行了分析。Fe层很薄时薄膜不连续,岛状分布的Fe颗粒使多层膜显示超顺磁特性。Fe/Ru界面的高分辨电镜观察发现,界面存在粗糙度的不对称性,它是多层膜中产生正磁阻的重要原因。Fe/Ru多层膜的负磁阻在退火后得到较大的提高,表明Fe/Ru多层膜的负磁阻主要来源于界面的粗糙度。     

低转速下多弧离子镀制备的Mo-Ti-Al-N超晶格硬质涂层的微结构及背散射谱分析

目的研究低基片转速对纳米多层膜微结构和性能的影响。方法采用阴极多弧离子镀技术在单晶硅基片上沉积制备了MoTiAlN/MoN/Mo纳米复合结构涂层,借助X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)、背散射谱(RBS)和纳米硬度计,分别对样品的物相、形貌、组分和硬度进行表征分析。结果 XRD显示不同转速下制备的涂层的物相结构主要为六角密排结构的Mo N和面心立方(Ti,Al)N,较高基片转速下涂层的结晶性较好。SEM和TEM图像证实,2 r/min基片转速下的目标涂层具有平均调制周期26 nm的Ti AlN/MoN超晶格结构,总厚度为1.15μm,且界面清晰。纳米显微硬度测试表明,低基片转速下,涂层硬度和杨氏模量分别达到(30±2)GPa和(500±30)GPa。结论不同能量的~7Li~(2+)离子卢瑟福背散射谱结合SIMNRA拟合程序,可定量评估该超晶格结构涂层的原子百分比、每个子层的物理厚度及调制周期,这为纳米多层膜的微结构表征提供了一种有效的分析手段。     

Co/Cu/Co纳米多层膜的铁磁耦合效应

采用洛仑兹电子显微镜研究了磁控溅射沉积制备的Cu(20 nm)/Co/Cu/Co纳米多层膜磁畴结构随铁磁层间耦合效应的变化. Cu中间层厚度较薄时, 由于铁磁层之间的耦合作用, 纳米多层膜为垂直易磁化, 磁畴为磁泡结构, 磁泡的平均直径随Cu中间层厚度的增加而减小, 多层膜矫顽力呈减小趋势. 当Cu中间层厚度大于3 nm时, 铁磁层之间的耦合作用减弱, 纳米多层膜为面内易磁化, 磁泡结构的磁畴消失, 全部为具有波纹状的接近180°畴壁的磁畴结构.     

气相沉积铁钇多层膜的磁学性能

研究了气相沉积技术制备的Fe/Y多层膜的磁学性能,试验结果表明,当多层膜中铁层厚度减少到1．4nm时,薄膜由铁磁性转变为超顺磁性;多层膜的饱和磁化强度随铁层厚度的减少和钇层厚度的增加而显著降低。     

亚稳态化合物Ce_2Fe_(23)B_3的结构与磁性

研究了非晶态Ce_2Fe_(23)B_3合金的晶化以及亚稳态化合物Ce_2Fe_(23)B_3的结构与磁性XRD分析证实,Ce_2Fe_(23)B_3为bcc结构,晶格常数α=1.417nm由Ce_2Fe_(23)B_3的室温Mossbauer谱,确定不同Fe位Fe原子磁矩的大小依次为:μFe(48e_1)>μFe(48e_2)>μFe(48e_3)>μFe(16c)>μFe(24d),平均每个Fe原子和Ce原子的磁矩分别为1.94和0.85μB     

TiAlN/CrAlN纳米结构多层膜的结构与性能

采用射频磁控溅射方法制备了单层TiAlN、CrAlN复合薄膜以及不同调制周期和不同层厚比(lTiAlN/lCrAlN)的TiAlN/CrAlN纳米结构多层膜.薄膜采用X射线衍射仪、扫描电子显微镜、显微硬度仪进行表征.结果表明:TiAlN、CrAlN复合薄膜和TiAlN/CrAlN多层膜均为面心立方结构,呈(111)面择优取向.TiAlN/CrAlN多层膜的择优取向与调制周期和层厚比无关.层厚比为1的TiAlN/CrAlN多层膜的硬度依赖于调制周期,在调制周期为8 nm时,达到最大;固定TiAlN的厚度为4 nm,改变CrAlN层的厚度,在研究范围内,多层膜的硬度随着CrAlN层厚度的增加而增加.探讨了多层膜的致硬机制.TiAlN/CrAlN多层膜抗氧化温度比其组成单层膜高了近200 ℃,并讨论了其抗氧化机制.     

反应磁控溅射TiN/AlON纳米多层膜的微结构与显微硬度

采用Ti靶和Al2O3靶在Ar、 N2混合气氛中进行反应磁控溅射的方法,制备了一系列不同AlON层厚度的TiN/AlON纳米多层膜,利用EDS、XRD、HRTEM和微力学探针研究了AlON的形成条件以及AlON调制层厚的改变对多层膜生长方式和显微硬度的影响.结果表明,在Ar、N2混合气氛中对Al2O3进行溅射,N原子会部分取代Al2O3中的O原子,形成非晶态的AlON化合物.在TiN/AION纳米多层膜中,由于TiN晶体层的模板效应,AlON层在厚度小于0.6 nm时被强制晶化并与TiN形成共格外延生长结构,多层膜显示出最高硬度达40.5 Gpa的超硬效应;进一步增加AlON的层厚,其生长模式由晶态向非晶态转变,破坏了多层膜的共格外延生长结构,多层膜的硬度随之降低.     

金刚石表面镀钛及界面微结构的研究

本文研究了应用真空微蒸发镀方法实现了金刚石表面镀钛.X-射线衍射分析表明:镀钛层物相为TiC和Ti,反应形成的界面结构层次为:金刚石-TiC-Ti.TiC层一般厚度在几百到上千埃,镀Ti层总厚度大约150 nm-200 nm.根据金刚石、TiC和Ti的晶体结构特点,应用结构对应原则,创建了金刚石/TiC/Ti共格界面模型.金刚石和TiC之间的共格界面为:(111)金刚石∥(111)TiC,C原子的周期性对应关系为:6 ×0.252 nm≈5×0.304 nm,C原子错配率为0.526%;金刚石和TiC界面间的C原子形成垂直的键、偏斜的键和桥式三中心键.六方结构α-Ti的和面心立方的TiC之间的共格界面为:(1000)α-Ti∥(111)TiC,形成垂直键,Ti原子错配率为0.66%.     

电化学法制备Fe/Pt多层膜的工艺研究

通过电化学沉积法制备Fe/Pt多层膜。分别以FeSO4.7H2O和H2PtCl6.6H2O作为Fe2+源和Pt4+源,配置Fe/Pt摩尔浓度比为100:1混合溶液,调整其pH值为2.5。然后以铂片为阳极,以纯铜片为阴极,接通脉冲电源,调节电位、换向时间等参数实现Fe、Pt的反复沉积,获得Fe/Pt多层膜。结果表明,变换富Fe层沉积电位对多层膜的表面形貌有一定影响。在富铂层沉积电位为-2V,沉积6min和富铁层沉积电位为-5V,沉积3min,循环4个周期得到的多层膜的Fe/Pt原子比接近3:1。将此多层膜在550℃热处理30min之后,其矫顽力从5.12kA/m增大至42.18kA/m,饱和磁化强度从43.1kA/m增大至459.1kA/m。     

Ru籽晶层对CoCrPt-SiO_2垂直记录层形貌及结构的影响

采用磁控溅射方法,制备了以不同厚度Ru薄膜为籽晶层的CoCrPt-SiO2垂直磁记录薄膜。利用原子力显微镜(AFM)、透射电镜(TEM)分析Ru薄膜的结构和形貌,并研究了其结构对CoCrPt-SiO2薄膜表面形貌、粗糙度及结构的影响。结果表明,CoCrPt-SiO2记录层的晶粒尺寸和粗糙度均随着Ru籽晶层厚度的增加而增加,薄而粗糙的籽晶层适合于高密度磁记录介质。对于CoCrPt-SiO2记录层晶粒的优化,厚度为70nm的Ru籽晶层有利于记录层薄膜晶粒的完全隔离,从而提高了磁记录性能。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。