镍基单晶合金的厚度效应

考察了镍基单晶合金ＤＤ３板试样在厚度为０．５，１．０，２．０ｍｍ、晶体取向为［００１］，［０１１］，［１１１］和［１１２］以及试验温度为１０００，９５０，８５０和７６０℃下的变形和破坏规律。宏观结果表明，厚度效应表现出与温度的相关性：１０００℃时，试样越薄，屈服强度越高；９５０℃以下，试样越厚，屈服强度越高。ＳＥＭ细观断口形貌分析表明，除１０００℃［００１］取向试样断口表现出韧窝断裂模式外，其余试     

纯铁离子渗稀土表层结构研究

本文利用辉光放电离子溅射法成功地将稀土元素Ｌａ，Ｃｅ离子化，并以较高的浓度渗入纯铁．采用金相、电子探针、能谱（ＥＤＡＸ）及透射电镜（ＴＥＭ）等方法研究了被渗试样的渗层结构，确定出稀土元素在纯铁中的两种存在形式：固溶和亚稳的金属间化合物（Ｃｅ，Ｌａ）Ｆｅ_７，选区电子衍射证明，ＣｅＦｅ_７与α－Ｆｅ之间存在如下取向关系（０１１）α－Ｆｅ∥（１１０）ＣｅＦｅ７，［１１１］α－Ｆｅ∥［００１］ＣｅＦｅ７．观察表明，稀土元素原子的渗入可促使铁基体中固溶的微量碳原子向试样外表面扩散并偏聚．     

镍基单晶高温合金CMSX—4相形态演变及蠕变各向异性

研究了１２５３Ｋ，３５０ＭＰａ拉伸蠕变过程中（００１），（１１０）和（１１１）取向镍基单晶高温合金ＣＭＳＸ－４基体相γ和析出相γ的演变方式及相尺寸的变化规律，比较了不同取向单晶试样中γ和γ′特征尺寸的变化对蠕变应变量和应变速率的影响，结果表明，沿γ′定向粗化方向上γ基体通过宽度（即相邻γ′的间距）的变化经对蠕变应变量和应变速率的影响较为明显，根据不同取向试样中γ基本通道的演变规律和塑性变形机制综合     

DD15单晶高温合金的蠕变各向异性

在定向凝固炉中制备了［001］、［011］和［111］3种不同取向的DD15单晶高温合金，研究了980 ℃/300 MPa条件下不同取向的蠕变性能。为对比分析不同蠕变时间后的微观组织，蠕变50和100 h后停止试验。采用扫描电镜和透射电镜分析不同取向的合金组织。结果表明，不同取向合金在垂直于生长方向的截面上具有不同的组织特征，［001］取向γ′相为规则的正方形，［011］取向γ′相为矩形，［111］取向γ′相为多边形。合金在 980 ℃/300 MPa条件下的蠕变性能呈现明显的各向异性，蠕变寿命按［111］、［001］、［011］取向的顺序减小，应变量按［001］、［011］、［111］取向的顺序降低。3种取向合金蠕变曲线的共同特征为具有非常短的蠕变第1阶段，与［001］和［111］ 取向相比，［011］取向合金具有较短的蠕变第3阶段。不同取向合金蠕变后的γ′相具有明显不同的筏排化程度。［001］取向合金的γ′相筏排化速率大于［011］和［111］取向合金。蠕变断裂后，［001］或［111］取向合金的位错密度大于［011］取向合金。     

单晶Nb拉伸,压缩及恒应变疲劳后的滑移系和滑移特征

研究了单滑移位向和多滑移位向Ｎｂ单晶在拉伸，压缩及循环变形时的滑移系，根据试样表面滑移线的方向，在极图上确定滑移面，单滑移位向（［３２１］）的单晶，在拉伸时的滑移系为（１０１）［１１１］，在压缩时是（１０１）［１１１］和（２１３）［１１１］．根据ｂｃｃ晶体变形特点，分析了拉伸，压缩和循环变形的滑移系之间的关系，用光学显微镜和透射电镜复型观察了试样的表面形貌，确定了多滑移位向（［１１０］位向）单晶滑     

LOW－ANGLE TILT GRAIN BOUNDARY BETWEEN MARTENSITE LATHES IN 9Ni STEEL

利用透射电镜和高分辨电镜对９Ｎｉ钢合金显微结构进行了观察，发现在几种不同热处理条件下，样品中的同一马氏体束内二相邻马氏体片的［１１０］_Ｍ方向间存在约５．３°的角度差．本文提出了一个类Ｂａｉｎ转变关系：［１０１］_Ａ∥［１１１］_Ｍ，（０１０）_Ａ∥（１１０）_Ｍ，可以合理解释这一现象．     

TiAl单晶中〈011]超点阵位错滑移的临界分切应力(CRSS)与晶体取向的关系

γ—ＴｉＡｌ单晶中,＜０１１］超点阵位错的运动方向同晶体取向有关、当沿极射投影图００１一１１０—０１０单位三角形的００１－１１１－０２１区域中的取向变形时,ＳＩＳＦ偏位错为领先位错;而沿三角形中其余区域中的取向变形时,ＡＰＢ偏位错为领先位错．在反常温度区域中（即超点阵位错开动的温度范围内）,前者的ＣＲＳＳ较高,形变的热激活焓也较高,＜０１１超点陈位错的脱钉过程更为困难,造成ＣＲＳＳ反常上升的速率较快．     

一种镍基单晶高温合金中γ＇沉淀的定向粗化

研究了［００１］取向单晶高温合金ＣＭＳＸ—４在１２５３Ｋ，３５０ＭＰａ拉伸蠕变中γ＇沉淀沿垂直于外应力轴方向的粗化过程及其机理。发现在定向粗化期间立方形γ＇沉淀的边缘部分优先生长，γ—γ＇界面呈内凹形方式推进，进而封闭了与之相邻的垂直基体通道（平行于［００１］）；相互连接的γ＇沉淀逐渐消耗并最终耗尽被封闭的残余垂直通道而发展成完整的筏形组织。定向粗化导致了γ＇沉淀沿［００１］方向的尺寸逐渐减小，水平基体通道（垂直于［００１］）的宽度大幅度增加。对γ＇沉淀的特殊生长方式和两共格相形貌的演变特征进行了分析与讨论。     

DIRECTIONAL COARSENING OF γ'PRECIPITATES IN A SINGLE CRYSTAL NICKEL BASE SUPERALLOY

研究了［００１］取向单晶高温合金ＣＭＳＸ—４在１２５３Ｋ，３５０ＭＰａ拉伸蠕变中γ＇沉淀沿垂直于外应力轴方向的粗化过程及其机理。发现在定向粗化期间立方形γ＇沉淀的边缘部分优先生长，γ—γ＇界面呈内凹形方式推进，进而封闭了与之相邻的垂直基体通道（平行于［００１］）；相互连接的γ＇沉淀逐渐消耗并最终耗尽被封闭的残余垂直通道而发展成完整的筏形组织。定向粗化导致了γ＇沉淀沿［００１］方向的尺寸逐渐减小，水平基体通道（垂直于［００１］）的宽度大幅度增加。对γ＇沉淀的特殊生长方式和两共格相形貌的演变特征进行了分析与讨论。     

纯铁离子渗氮扩散层中α″→γ′氮化物的转变

利用透射电子显微镜对纯铁离子渗氮扩散层中的γ′－Ｆｅ４Ｎ氮化物进行微观分析时发现,组织中存在两种类型的γ′－Ｆｅ４Ｎ 通过其内部是否含有高密度的单方向平行层错片可以将二者区分开来、实验中观察到了直接生长在α″－Ｆｅ１６Ｎ２上的 γ′－Ｆｅ４Ｎ氮化物,证实组织中存在α″→γ′氮化物的转变．通过此氮化物转变生成的γ′－Ｆｅ４Ｎ,其内部含有单方向排列的平行层错片,根据 α″－Ｆｅ１６Ｎ２和γ′－Ｆｅ４Ｎ的晶体结构讨论了氮化物转变的结构条件,转变过程中二者保持如下的取向关系：（１１１）γ′／／（１１０）α″,［１１０］γ′／／［１１１］α″．     

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。