Cu-Cr合金在3.5％NaCl+H2SO4溶液中脱铬腐蚀行为

通过金相、扫描电镜(SEM／EXD)，结合X射线衍射(XRD)研究了Cu-Cr合金在3.5％NaCl+H2SO4溶液中脱铬腐蚀行为。结果表明，Cu-Cr合金脱铬腐蚀首先发生在Cr相的界面处，并向Cr相内继续扩展，随H2SO4浓度增大及温度升高，其脱铬腐蚀倾向加大。     

变形对Cu-Cr合金脱铬腐蚀的影响

针对Cu—Cr合金在HCl溶液中脱铬腐蚀问题，借助金相测试手段研究了变形对Cu-Cr合金脱铬腐蚀的影响。结果表明：试样变形量越大，Cu-Cr合金脱铬孕育期越短，脱铬倾向增大。     

Cu-Cr合金在3.5%NaCl+NH3溶液中的腐蚀行为

通过金相、X射线衍射及扫描电镜(SEM／EDX)，结合电化学测试手段，研究了Cu-Cr合金在3．5％NaCl NH3溶液中的腐蚀行为，并探讨了NH3浓度对其腐蚀性能的影响。结果表明：Cu-Cr合金中铜相较铬相易腐蚀，其腐蚀速率随NH3浓度的增加而增大。     

Cu—Cr合金在H2—H2S混合气中的腐蚀行为

研究了Cu-Cr合金及纯铜、纯铬在500－600℃,硫分压为10^-5Pa时的硫化腐蚀。两种Cu-Cr合金的腐蚀速度均介于两种纯金属之间,并随温度的升高而增大,但在两种Cu-Cr合金的表面均形成了复杂的腐蚀产物膜,外层为Cu2S层,有时不连续甚至剥落,中间层为二元Cu-Cr硫化物CuCrS2,内层为二元Cu-Cr硫化物CuCr2S4和CrS的混合物,有时也包含未被腐蚀的金属铬颗粒。在腐蚀区以下的合金基体中没有铬的贫化现象发生。这种腐蚀膜结构的形成是合金中存在两相的结果。     

Ti-Zr基块体非晶合金在NaOH溶液中的腐蚀研究

采用电化学极化曲线和变温失重法研究了Ti_(35)Zr_(30)Be_(20)Cu_(7.5)Co_(7.5)块体非晶合金分别在0.5、1、2 mol/L NaOH溶液中的腐蚀行为,并比较了304不锈钢的耐蚀性。极化曲线测试结果表明,Ti_(35)Zr_(30)Be_(20)Cu_(7.5)Co_(7.5)块体非晶合金在0.5、1、2mol/L NaOH溶液中均表现出良好的耐蚀性,阳极极化曲线表现出明显的钝化特征。随着NaOH溶液浓度的增大,极化曲线左移,耐蚀性降低。非晶合金的自腐蚀电位高于不锈钢。在293、313、333K,2mol/L NaOH溶液的不同温度失重腐蚀中,随温度增加,其非晶合金均较不锈钢耐蚀性高。探讨了NaOH溶液浓度变化、温度变化对Ti_(35)Zr_(30)Be_(20)Cu_(7.5)Co_(7.5)块体非晶合金的耐蚀性机理。     

变电站电缆用Cu-Cr合金在高温暴露环境下的腐蚀行为研究

研究了电缆用二元合金Cu-Cr在600℃下的腐蚀行为。结果表明,未经过晶粒细化处理的Cu-Cr二元合金腐蚀后的氧化产物主要是氧化铜,存有极少数的氧化铬附在氧化铜的内膜上。经过晶粒细化处理后的Cu-Cr二元合金,其氧化产物为氧化铜和氧化亚铜,还有一些氧化铬弥散分布于氧化物的内部。二元合金的氧化速度随铬含量的升高而降低,腐蚀氧化物的分布与形态还与具有抗氧化能力的β相有关。     

Al-In-Mg系铝合金阳极在NaOH溶液中的电化学行为

以Al-In-Mg合金为基础，选择添加Pb、Mn、sn制备了4类铝合金阳极材料。通过自腐蚀、开路电位、阳极极化方式研究了该系列合金阳极在c(NaOH)=4mol／L溶液中的电化学腐蚀行为，初步分析了合金成分、介质温度及溶液缓蚀剂对合金阳极性能的影响。结果发现：制备的3#(Al-In-Mg-Sn)合金、4#(Al-In-Mg-Sn-Pb)合金阳极在c(NaOH)=4mol／L c(Na2SnO3)=0．04mol／L溶液中表现出更好的电化学性能，具有比纯铝(99．95％)更负的开路电位，更小的自腐蚀速率和更低的阳极极化。     

国产825合金的耐腐蚀性能研究

采用腐蚀失重法、电化学测试和慢应变速率拉伸应力腐蚀研究了国产825合金在HCl、NaOH和NaCl溶液中的腐蚀行为,并采用金相显微镜和扫描电镜（SEM）对腐蚀后的样品进行观察。结果表明,国产825合金在HCl溶液中浸泡7 d后发生了明显的腐蚀,腐蚀速率随HCl浓度的增加而增大,而在NaOH和NaCl溶液中浸泡5个月后未发生明显腐蚀,并且在HCl、NaOH和NaCl溶液中合金的腐蚀电流随溶液浓度增加而增大。慢应变速率拉伸应力腐蚀结果表明在HCl、NaOH和NaCl溶液中合金的应力腐蚀敏感性很小,因此,一般情况下不会发生应力腐蚀开裂。     

氢氧化钠溶液浓度对Fe-Cr-Mo-C-B非晶合金涂层耐腐蚀性能的影响

利用电化学极化曲线方法、交流阻抗谱(EIS)技术和扫描电子显微镜(SEM)研究了Fe44Cr16Mo16C18B6非晶合金涂层在不同浓度NaOH(质量分数为10%,20%,30%)溶液中的电化学腐蚀行为。电化学测试结果表明,Fe44Cr16Mo16C18B6非晶合金涂层在NaOH溶液中的阳极极化曲线出现了宽的钝化区,并且发生了二次钝化,钝化区随着NaOH溶液浓度的增大而变窄。EIS图谱由高频感抗弧和低频容抗弧构成,利用R(RL)(Q(R(CW)))等效电路模型能有效地解释此合金涂层的腐蚀性能。SEM观察发现,Fe44Cr16Mo16C18B6非晶合金涂层的表面腐蚀产物随着溶液浓度的增加而变厚,并伴有脱落的现象。     

C——Cr合金在3.5％NaCl＋H2SO4溶液中脱铬腐蚀行为

通过金相、扫描电镜(SEM/EXD)，结合X射线衍射(XRD)研究了Cu—Cr合金在3．5％NaCl H2SO4溶液中脱铬腐蚀行为。结果表明，Cu—Cr合金脱铬腐蚀首先发生在Cr相的界面处，并向Cr相内继续扩展，随H2SO4浓度增大及温度升高，其脱铬腐蚀倾向加大。     

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).     

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.     

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.     

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。