钴镍铜合金纳米线的制备及微波吸收性能

采用脉冲电化学法沉积法在AAO模板上制备了钴镍铜合金纳米线,XRD测试表明纳米线有Co,Ni,NiCu和CoCu4个磁性相共存。在平行于和垂直于长轴方向上所测的磁滞回线表明:钴镍铜合金纳米线阵列具有弱的各向异性。磁性合金纳米线与石蜡的复合材料在GHz频段内具有较好的电磁波吸收性能:当吸波涂层的厚度为4mm时,其最小反射损耗可达–30dB。     

非水体系中电沉积稀土永磁功能合金纳米线

利用多孔阳极氧化铝模板，在尿素-NaBr-KBr-酰胺体系中电沉积稀土-铁系金属（La-Co）合金纳米线。用扫描电子显微镜（SEM）观察（La-Co）合金纳米线的表面形貌，用磁振动样品磁强计（VSM）研究了LaCo合金的磁性。结果表明，纳米线直径较为均匀，且每条纳米线的尺寸为70～80nm，与AAO模板的纳米孔径大小相符合：X射线衍射（XRD）分析表明，La-Co合金为LaCo5晶体;在室温下呈现顺磁性的La，当与Co形成合金后，饱和磁矩接近于磁性金属Co。     

随机分布Fe纳米线复合材料的吸波性能

在具有纳米级孔洞的多孔氧化铝模板上,用电沉积方法制备出α-Fe纳米线有序阵列组装膜.用10%NaOH将纳米线溶液解离,并使之与树脂混合均匀,制成随机分布Fe纳米线/绝缘体复合吸波材料,并对其吸波性能进行了研究.研究结果表明:随铁纳米线体积分数的提高,随机分布的Fe纳米线/绝缘体复合吸波材料的电磁参数也随之增大;用测试电磁参数计算了不同厚度的反射率,体积分数为25%随机分布的铁纳米线/绝缘体的复合吸波材料最佳吸收厚度为1.14 mm;在9.7 GHz时,反射率达-45 dB,小于-5 dB时,反射率带宽达到9 GHz;随铁纳米线/绝缘体的复合吸波材料厚度的增加,吸收峰位向低频移动;随铁纳米线体积分数的增加,其吸收率明显增大,同时最佳吸收厚度也减小.     

AAO模板合成法制备金属Ni磁性纳米线阵列的研究

利用电化学沉积法,在AAO模板上制备了铁磁性金属Ni纳米线有序阵列.通过XRD、SEM等分析测试方法研究了制备工艺与Ni纳米线结构的关系,并在此基础上研究了结构对其磁性能的影响.在恒定沉积电压为-2 V时,适当的电流密度(2 mA/cm2)以及较长的沉积时间(9 h),有助于得到沿着[220]方向的高织构性纳米线.另外,相对于多晶结构,单晶或高织构性结构的Ni纳米线具有较高的矫顽力、剩磁及更显著的磁各向异性.     

AAO模板法制备Pd-Ni合金纳米线

在孔深60gm，直径200nm的通孔氧化铝模板中，用60mmol·dm^-3。Pd（NH3）4Cl2＋40mmol·dm^-3NiSO4·6H2O＋0．2mol·dm^-3NH4Cl，pH8．5和70mmol·dm^-3。Pd（NH3）4Cl2＋30mmol-dm^-3NiSO4·6H2O＋0．2mol·dm^-3NH4Cl，pH8.5的2种电解液，采用直流电沉积的方法制备钯镍合金纳米线阵列。借助扫描电子显微镜（SEM）和X-射线能谱仪（EDX）表征纳米线的形貌和成分。结果表明，用-0．6V～-0．8V（vsSCE）的直流电沉积，在氧化铝（AAO）模板中可以成功地制备出镍含量在8％～15％（质量分数，下同）之间的Pd-Ni合金纳米线有序阵列，其直径和模板的孔径是一致的。沉积电势负移将使得电流密度增加，有利于合金中电势较负金属镍含量的增大。     

CO/Al2O3纳米线有序阵列的制备与磁性

用电化学法制备了高度有序的多孔氧化铝模板(AAO),用交流沉积法以硫酸盐为电解液在多孔氧化铝模板中还原生长了Co纳米线,制备了Co/Al2O3纳米线有序阵列.通过电化学脉冲剥离法去除了沉积在阵列表面的过剩金属钴和金属铝基底,提高了样品的磁垂直各向异性.分别用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)对多孔氧化铝模板和纳米线阵列的微观形貌和结构进行了分析,用振动样品磁强计(VSM)对样品的磁学性质进行了测试.分析了模板孔径、孔心距、长径比以及交流电化学沉积条件如pH值、温度等对纳米线结构和磁性能的影响.孔心距和长径比一定的条件下,孔径增大引起孔壁厚度降低会导致纵向矫顽力和剩磁比下降.纳米线中的晶粒在生长过程中(100),(002)择优取向.当外场垂直磁化时,磁滞回线有较高的矩形比(0.6～0.85)和矫顽力(80 000A/m～150 400A/m),具有明显的垂直膜面各向异性,矩形比和矫顽力都比一般的二维合金薄膜材料大得多.     

双相FeNd纳米晶的微波磁导率调控及其吸波特性研究

采用熔体快淬制备NdFe二元合金甩带，获得较细的纳米晶，经粉碎及处理后，采用体积比为50％的含量与石蜡混合，进行2GHz～12GHz频段的电磁性能测试，获得了较好的微波电磁性能，其中Nd8Fe92在2GHz处μr=4．5-j2．2，εr=128-j45，当厚度为1．2mm，分别模拟得到微波频率在4GHz附近反射率衰减为-8．5dB（86％的能量损耗），在2GHz附近衰减为-5．8dB（75％的能量损耗）的性能。模拟后可根据不同频率需要设计成在一定厚度和Nd元素含量比的微波吸收材料。     

模板法电沉积钆钴合金纳米线阵列

在草酸电解液中用二次阳极氧化法制备多孔阳极化氧化铝(Anodic Aluminum Oxide,AAO)模板。通过对电流密度、氧化时间、电解液浓度等参数的调整,最终获得孔洞分布均匀、孔径基本一致、孔口呈六边形的AAO模板。采用不去除中间铝,用逐级降压法和电化学法减薄阻挡层,然后利用中间铝作为电极,在非水体系中以AAO为模板,直流电沉积钆钴合金纳米线阵列。经过SEM观测,AAO模板孔径在60nm左右,去阻挡层前后变化不大,制备的钆钴合金纳米线排列有序、尺寸一致;EDS测定表明纳米线为钆钴合金及少量氧化物纳米线,钆钴摩尔质量比为1:7.5,钆钴合金质量分数为90.66%;XRD分析图谱表明所得到的钆钴合金纳米线为非晶态。     

原位模板法在铝基底上制备TiO2纳米管阵列薄膜

采用液相沉积法，将铝基多孔阳极氧化铝（AAO）模板浸入到（NH4）2TiF6溶液中，制备出高度有序的TiO2纳米管阵列薄膜，并在不同的温度下进行了热处理。用场发射扫描电子显微镜、透射电子显微镜和X射线衍射仪等手段对试样的微观形貌、结构及物相进行了表征。结果表明，TiO2纳米管的形貌依赖于AAO的特征，薄膜是由外径大约200nm，壁厚约40nm的TiO2纳米管阵列组成，薄膜厚度约25μm。原位模板法制备的TiO2纳米管阵列薄膜为非晶态，在400℃空气中焙烧2h转变为锐钛矿相TiO2。经过650℃焙烧仍保持纳米管结构，表现出较好的热稳定性。     

模板法制备CdSe纳米线及其光学性质的研究

利用恒电位沉积方法,在阳极氧化铝(AAO)模板里沉积了CdSe纳米线。对其进行了结构和光学性质的表征,并且用循环伏安法讨论了其沉积机理。结果表明:室温下,0.1 mol·L-1CdSO4+0.25 mol·L-1H2SO4+50 mmol·L-1 SeO2配比的溶液,0.4 V恒电位沉积,在AAO模板中制备出了CdSe纳米线。EDS的结果表明Cd和Se的化学计量比接近于1:1;通过XRD确定了所沉积的CdSe为面心立方结构,其择优取向为(111)晶面。紫外可见分光光度计吸收光谱表明其吸收范围在400~700 nm,吸收最大处在500 nm,PL发射谱表明CdSe纳米线的发光峰在400 nm左右。     

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。