双辉等离子渗铬T8钢碳迁移现象的分析

用双辉等离子渗铬技术，进行了880～900℃温度下的T8钢表面渗铬合金化研究；测量了渗铬层中Fe、Cr和C等元素的浓度分布，分析了渗铬合金化层形成过程中碳迁移行为。结果表明，对T8钢进行双辉等离子渗铬处理时，奥氏体中碳化学位下降引起的从基体向渗层的碳迁移是必然的，但通过控制工艺参数，由阴极溅射引起的表面脱碳是可以减轻的。     

45钢表面含钛高速钢渗层的研究

在45钢表面进行W、Mo、Ti离子三元共渗，以形成类似高速钢成分的合金化渗层；对该合金化渗层进行渗碳、淬火、回火处理。结果表明，离子渗金属后，渗层组织为合金铁素体，表面合金元素浓度(质量分数，％)为8W、10Mo、1．8Ti；渗层经渗碳后，显微组织为粒状合金珠光体 不同形状的合金碳化物，合金碳化物的分布与普通高速钢相比更为细小、弥散、均匀；渗碳试样经淬火、回火处理后，渗层显微组织为回火马氏体和均匀细小的粒状碳化物，合金碳化物为M。C(Fe，w，C)、M。C，[(FewMo)7C3]和MC(TiC、r-MoC)，硬度为800～890HV0．1(相当于64～67HRC)，红硬性为760HV0．1左右(相当于63HRC)。     

等离子表面复合渗合金层碳化物相的研究

利用等离子表面合金化技术，在碳钢表面进行W、Mo、C共渗，共渗合金层中W当量质量分数超过10％，含碳量超过平衡碳计算值，碳饱和度达1．6以上，约是一般冶金高速钢碳饱和度的两倍。用X射线衍射分析了共渗合金层中碳化物的结构类型；用电子探针进行微区成分分析，测定碳化物的成分，并计算了碳化物中碳原子与合金元素之间的原子比。结果表明，共渗合金层中的碳化物主要是由合金元素W、Mo和C形成的M6C型碳化物及少量的M2C型碳化物。M6C型碳化物中碳原子与合金元素之间的原子比为1．6～3．2：1平均为2．4。与一般冶金低合金高速钢中的合金元素与碳原子比相比较，范围窄，且偏低。     

Q235钢铬铝共渗及耐高温氧化性

为提高Q235钢的耐氧化性和耐蚀性，进行了渗铬和渗铝，在此基础上进行了铬铝共渗。用光学显微镜、透射电镜和电子探针研究了渗层的显微组织、相结构及成分分布．结果表明，渗剂成分为93％Cr、7％Al时，经1100℃×16h共渗后，渗层表面铬、铝含量分别为18％和8．2％；表层组织为（Cr，Fe）23C6＋AlFe3C0.69，里层为α－Fe（Cr，Al），渗层具有较高的耐高温氧化性和抗蚀性。     

表面高Cr高C合金层摩擦性能的研究

介绍一种Q235钢表面进行双层辉光离子渗Cr方法,表面Cr含量达到40%左右.然后进行超饱和渗C,形成高Cr高C表面合金化层.表面含碳量达到2.7%左右,超过平衡碳计算值.随后进行淬火 低温回火热处理,使表面合金层获得马氏体基体上均匀分布的细小弥散碳化物组织,没有共晶莱氏体.经X射线衍射分析,合金化层碳化物类型为M23C6、M7C3,尺寸1～2 μm,表面硬度达到1200HV左右.将双层辉光离子渗Cr 渗C淬火试样,进行摩擦因数和耐磨性能试验,结果表明,高Cr高C合金化层的平均摩擦因数为0.11,相对耐磨性是Q235钢渗C淬火试样的1.83倍.     

Cr12MoV钢低温盐浴渗铬复合处理

研究Cr12MoV钢低温复合盐浴渗铬处理后复合渗铬层的金相组织、相结构、渗层厚度、渗层硬度、铬浓度分布和氮碳浓度分布，并进行渗层的耐磨性对比试验。结果表明，Cr12MoV钢经氮碳共渗加低温盐浴渗铬复合处理可获得良好的渗铬层及优异的耐磨性。     

W18Cr4V钢的低温盐浴渗铬研究

讨论W18Cr4V钢低温复合盐浴渗铬，分析复合渗铬层的成分、组织、结构和机械性能，并检验了复合渗铬层的耐磨性。结果表明，W18Cr4V钢经氮碳共渗加低温盐浴渗铬复合处理可获得良好的渗铬层及优异的耐磨性。     

碳含量及合金元素对低温盐浴渗铬层的影响

以45钢、T10钢及3Cr2W8V钢为例,使用OM、SEM等方法,研究了碳以及合金元素含量对低温盐浴渗铬层的影响.结果表明,钢的碳含量在低温盐浴渗铬过程中起到了促进作用,能增加渗铬层的深度,提高渗层的显微硬度和铬浓度,T10钢表面铬浓度为85.4％,45钢为81.3％,T10钢表面硬度为1 380 HV,45钢为1 290 HV;而合金元素则起到了阻碍作用,减少了渗铬层的深度,渗层的显微硬度和铬浓度均有所下降,3Cr2W8V钢表面硬度为1 280 HV,表面铬浓度为76.3％.     

3Cr2W8V模具钢低温盐浴渗铬复合热处理

研究了3Cr2W8V钢的低温盐浴渗铬工艺，分析了渗铬层的金相组织、结构和力学性能，并进行渗铬层的耐磨实验。结果表明，3Cr2W8V钢在经过低温盐浴渗铬复合处理后可以获得良好的渗铬层及优异的耐磨性。     

碳钢表面等离子高Cr合金层耐蚀性能的研究

在Q235钢表面进行双层辉光离子渗Cr，表面Cr含量约为40％，渗层厚度近50 μm；然后进行超饱和渗碳，表面含C量达到2.7％左右，超过Fe-Cr-C平衡碳计算值0.3％.随后进行淬火＋低温回火处理，经X射线衍射分析，合金化层碳化物类型为M23C6、M7C3.将双层辉光离子渗Cr＋渗碳淬火试样，在10％H2SO4、3.5％NaCl水溶液和H2S富液(含H2S 5～8 g/L，NH3·H2O 20 g/L)中，进行电化学腐蚀试验.结果表明，渗Cr试样在10％H2SO4、3.5％NaCl水溶液和H2S富液中的耐腐蚀程度比Q235基体试样，分别提高了2.35、3.10、2.14倍.     

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。