PZT陶瓷的氢致滞后断裂

ＰＺＴ压电陶瓷单边缺口恒载荷试样两面镀镍后在ＮａＯＨ溶液中动态充氢时能发生氢致滞后断裂．研究了氢致滞后断裂门槛应力强度因子和试样中可扩散氢浓度的定量关系．结果表明,氢致断裂归一化门槛应力场强度因子ＫＩＨ/ＫＩＣ(ＫＩＣ＝１．３４Ｍｐａ·ｍ１/２)随氢浓度对数的升高而线性下降,即ＫＩＨ/ＫＩＣ＝０．４－０．１５５ｌｎＣｏ．当Ｃｏ＝９．８４×１０－４%(对应充氢电流３００ｍＡ/ｃｍ２)时,ＫＩＨ＝０．０１ＫＩＣ．这表明,ＰＺＴ陶瓷具有极高的氢致开裂敏感性．     

金属分散的陶瓷基纳米复合材料

利用还原烧结法成功地制得Ａｌ２Ｏ３／金属复合材料。采用微细α－Ａｌ２Ｏ３（平均粒径０．２μｍ）与Ｗ金属粉（粒径０．６μｍ）混合物经烧结制取Ａｌ２Ｏ３／Ｗ复合材料时,为了获得分散的微细金属可采用ＷＯ３（平均粒径７０μｍ）相当于α－Ａｌ２Ｏ３粉末体积的２．５％至１０％,经球磨机混合后装入石墨模中,于１１７３～１３７３Ｋ进行３．６ｋｓ氢还原,再于１６７３Ｋ和３０ＭＰａ下热压烧结。还可以采用ＮｉＯ平均粒径６０μｍ）作为Ｎ原料,通过还原烧结制得Ａｌ２Ｏ３／Ｎｉ系复合材料。采用ＷＯ３作Ｗ原料通过还原烧结法制…     

机械合金化过程中粉末的形变及其能量转化

从分析实际机械合金化（ＭＡ）过程的碰撞出发,引入了碰撞角度因子,建立粉末应变及热温升高等与球磨工艺参量和碰撞角度因子之间的理论关系,粉末的热温长可表示为：△Ｔ＝ＣＰ＾－１／σ０εｍａｘ＋Ｋεｍａｘ＾ｎ＋１／（ｎ＋１）＿ｆｐｍａｘｖｂｔｓｉｎθ／２ｈ０」,粉末正应变及切应变分别为：ε＝ｌｎ「２ｈ０／２ｈｏ－ＶｂｃｏｓθＴ」γ＝ｖｂｓｉｎθＴ／ｈ０－πｆｐｍａｘｒｃ＾２Ｔ＾２／２０ｍｂｈｏ,可见ＭＡ过     

高强度高韧性钢的热处理与力学性能

研究了真空冶炼低碳Ｎｉ１０Ｃｏ１４Ｃｒ２Ｍｏｌ钢的碳含量，时效温度与力学性能的关系，初步探索了钢中加入稀土，镁元素的作用，试验结果表明，钢中含碳量为０．１６％时，经５１０℃时效，可获得高强度和高韧性：σｂ＝１５８５ＭＰａ，σ０．２＝１４７０ＭＰａ，Ｖ型缺口冲击韧度为５６Ｊ／ｃｍ＾２，平面断裂韧性ＫＩＣ＝１０５ＭＰａｍ＾１／２，钢中添加过量稀土，韧性显著降低，镁对性能影响不大。     

开关电源用的纳米晶Fe74Cu1Nb1Mo2Si13B9合金的磁性能

本文报道了新开发的纳米晶Ｆｅ７４Ｃｕ１Ｎｂ１Ｍｏ２Ｓｉ１３Ｂ９合金的综合磁性能。无磁场最佳退火后,直流磁性能达到下列水平：Ｂ８０＝１．１７Ｔ,Ｂ８＝１．０９Ｔ,Ｂｒ＝０．５４Ｔ,Ｈｃ＝０．８Ａ／ｍ,μｉ＝１３．１８×１０４,μｍ＝３１×１０４。典型高频铁损达到下列水平：Ｐ５／２０ｋ＝１３５ｋＷ·Ｍ－３,Ｐ２／１００ｋ＝３３０ｋＷ·Ｍ－３,Ｐ１／２００ｋ＝２７３ｋＷ·Ｍ－３,Ｐ０．５／７００ｋ＝５９８ｋＷ·ｍ－３,Ｐ０．２／１０００ｋ＝１８６ｋＷ·Ｍ－３。在宽的频率及幅值磁通密度范围内,对铁损进行了分析,给出了几个近似表达式,可用来粗略地估算铁损。简单地叙述了在较大输出功率的开关电源中试用情况。     

热处理引起的残余应力对LC4铝合金腐蚀开裂行为的影响

研究了时效制度对Ａｌ－Ｚｎ－Ｍｇ－Ｃｕ合金（ＬＣ４）双悬臂梁（ＤＣＢ）试样的残余应力分布及其对应力强度因子，腐蚀开裂行为的影响。结果表明，轴向残余拉应力可以引起试样弯曲成弓形，相当于ＤＣＢ试样附加一应力强度因子Ｋ１Ｒ，Ｋ１Ｒ随时效温度提高而减小，在自然时效状态Ｋ１Ｒ约１０ＭＰａ．ｍ＾１／２，１２０℃时效时态Ｋ１Ｒ约７．５ＭＰａ．ｍ＾１／２时，无外加载荷均可产生严重的腐蚀开裂现象，且具有沿晶断裂特征     

高强钢应力腐蚀门槛值随强度的变化规律

恒位移试样测量表明,４０ＣｒＭｏ钢在３．５％ＮａＣｌ水溶液中应力腐蚀（ＳＣＣ）门槛应力强度因子ＫＩＳＣＣ随屈服强度σｓ指数下降、即ＫＩＳＣＣ＝１．３８×１０６ｅｘｐ（－８．２６×１０－３σｓ）．动态充氢时氢致开裂（ＨＩＣ）门槛应力强度因子ＫＩＨ随试样中可扩散氢浓度Ｃ０（１０－６）的对数而线性下降,即ＫＩＨ＝３１．１－９．１１ｎＣ０． ＳＣＣ时也遵循这个规律．发生ＨＩＣ型ＳＣＣ的临界氢浓度Ｃｔｈ随σｓ指数下降,从而可导出ＫＩＳＣＣ＝ａｋ１ｅｘｐ（－ｋ２σｓ）;其中ａ＝３ＲＴ　／２（１＋ν）ＶＨ,ＲＴ是热能,ρ是裂纹止裂时的曲率半径,ＶＨ是氢在钢中的偏摩尔体积,ν为Ｐｏｉｓｓｉｏｎ比,ｋ１和ｋ２则是和成分及组织有关的常数．     

快速凝固（Sm1—xBx）Fe2合金的结构和磁性

采用真空单辊快淬法（铜辊,线速度达２０～２３ｍ／ｓ）将成分为（Ｓｍ１－ｘＢｘ）Ｆｅ２（ｘ＝０,０．０１５,０．０３,０．０４５,０．０６）合金锭,制成快速凝固的鳞片状合金,再经粉碎在３０ＭＰａ压力下,模压成φ１０ｍｍ圆片,然后进行ＸＲＤ分析,比磁化强度和磁致伸缩（λ″－λ┴）的测量。实验结果表明各样品只有少量非晶相,主要是ＳｍＦｅ２及少量的ＳｍＦｅ５和ＳｍＦｅ７化合物。样品（Ｓｍ０．９８５Ｂ０．０１５）Ｆｅ２和（Ｓｍ０．９４Ｂ０．０６）Ｆｅ２,在７２０ｋＡ／ｍ磁场下,比磁化强度分别为：５９．５,５２．３Ａｍ２ｋｇ－１,在８８５ｋＡ／ｍ磁场下（λ″－λ┴）分别为：－５１０×１０－６和－３１０×１０－６。     

Zr_（1－x）Ti_xM_（2．1）合金（M＝V_（0．1）Ni_（0．53）

Ｚｒ_（１－ｘ）Ｔｉ_ｘＭ_（２．１）合金（Ｍ＝Ｖ_（０．１）Ｎｉ_（０．５３）Ｍｎ_（０．３２）Ｆｅ_（０．０５）的吸氢特性和电化学特性用小电弧炉在氩气保护下熔炼了Ｚｒ１－ｘＴｉｘ（Ｖ０．１Ｎｉ０．５３Ｍｎ０．３２Ｆｅ０．０５）２．１（Ｘ＝０、０．１、０?..     

《ms》易溃散水玻璃砂的研究

研制了《ｍｓ》溃散剂及《ｍｓ》改性水玻璃。《ｍｓ》改性水玻璃砂ＣＯ２硬化抗拉强度大于０．２ＭＰａ，烘干抗拉强度大于２ＭＰａ，７２ｈ抗拉强度大于０．６ＭＰａ，６００～１１００℃的溃散功降到１～１６．３Ｊ。用于生产中、小型铸钢件，易清砂，旧砂回用率达７０％。     

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。