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．     

C90油管钢的氢损伤

对比研究了三种油管钢（宝钢的Ｃ９０和日本的ＳＭ９０及ＳＭ９５）的氢致开裂性能．ＳＭ９０，ＳＭ９５和Ｃ９０产生氢损伤的临界扩散氢质量分数（×１０~（－６））分别为１．７６，４．３和８．３８；临界全氢质量分数（×１０~（－６））分别为４．２４，６．３５和１０．２２三种钢在Ｈ_２Ｓ中的门槛应力σ_（ｔｈ）／σ_ｓ分别为０．６４，０．８０和０．８５．三种油管钢抗氢损伤能力和抗氢致滞后断裂的能力是一致的，以Ｃ９０为最好，它和氢的扩散系数无关．Ｃ９０钢缺口试样氢致滞后断裂门槛值Ｋ_（ＩＨ）与可扩散的氢质量分数ｗ_０有关，实验获得Ｋ_（ＩＨ）＝４６－１２．５１ｌｎ_（ｗ０）．理论分析和实验结果完全一致．对Ｃ９０钢，当ｗ_０≤４．８×１０－６时，在任何Ｋ_Ｉ／Ｋ_Ｃ下均将获得韧窝断口；ｗ_０≥７．６×１０~（－６），Ｋ_Ｉ／Ｋ_Ｃ≥０．５时，则氢致韧断；Ｋ_Ｉ／Ｋ_Ｃ≤０．４时，则氢致脆断．     

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．     

油井管钢氢致开裂门槛值研究

四种高强度油井管钢动态及氢时,进入试样的可扩散氢含量ｃ０和充氢电流ｉ成正比,而氢致断裂门榄应力σｃ与名义屈服强度σｔ之比和ｌｎｃ０成正比,即σｃ／σｔ＝Ａ－Ｂｌｎｃ０,测量了四种钢在Ｈ２Ｓ中浸泡进入试样的Ｃ０,求出相应的ｉｃ,用ｉｃ充氢时同的门槛应力σｃ（Ｈ）／σｔ和Ｈ２Ｓ中应力腐蚀门槛应力σＣ（Ｈ２Ｓ）／σｔ相一致,这表明,可用特定电流下的动态充氢来代替Ｈ２Ｓ应力腐蚀。     

不锈钢焊缝金的氢脆

用慢应变速率拉伸方法研究了不稳定型奥氏体不锈钢焊缝金属（３０８Ｌ和 ３４７Ｌ）以及母材（３０４Ｌ）的氢脆敏感性,分别研究了原子氢以及氢致马氏体对氢致塑性损失的贡献,结果表明,当可扩散的氢浓度Ｃ０大于临界值（约 ２５×１０－６－３０×１０－６）后三种不锈钢均会出现氢致马氏体（ε＋α’）,其含量 Ｍ随 Ｃ０升高而升高,即 Ｍ（ε＋α’）＝５４．２－２５ ｅｘｐ（－Ｃ０／１５３）．氢致马氏体引起的塑性损失Ｉδ（Ｍ）随马氏体含量线性升高,即 Ｉδ（Ｍ）＝０４５Ｍ＝２４．４－１１．３ ｅｘｐ（－Ｃ０／１５３）１００％马氏体引起的最大塑性损失约为 ４５％,动态充氢引起的塑性损失几减去充氢除气试样的塑性损失就是原子氢引起的塑性损失Ｉδ（Ｈ）,它随 Ｃ０升高而升高,但当 Ｃ０＞１０－４后,Ｉδ（Ｈ）趋于最大值（对应 ε＝５ × １０－６／ｓ）,即 Ｉδ（Ｈ）ｍａｘ＝４４％（３０８Ｌ）,Ｉδ（Ｈ）ｍａｘ＝４５％（３４７Ｌ）以及 Ｉδ（Ｈ）ｍａｘ＝４０％（３０４Ｌ）．随应变速率ε升高,Ｉδ（Ｈ）逐渐下降,直至为零（对应 ε＝０．０１８／ｓ—０．０３２／ｓ）;即 Ｉδ（Ｈ）＝－１６．４—１０．６ ｉｇε（３０８Ｌ）,Ｉδ（Ｈ）＝－２０．９—１２．１     

环境诱导氢致断裂的非比例过载效应

研究连续充氢条件下短时非比例过载对４２ＣｒＭｏ钢／０．５ｍｏｌ／Ｌ Ｈ２ＳＯ４体系氢致断裂寿命的影响。结果表明；短时非比例过载对于ＨＩＦ的影响较之比例过载更为严重     

Nd含量对Fe76.5—xCu1.0NbxSi13.5B9.0纳米软磁合金磁性的影响

研究了Ｆｅ７６．５－ｘＣｕ１．０ＮｂｘＳｉ１３．５Ｂ９．０纳米软磁合金的磁性，发现当Ｎｄ含量ｘ＝３．０ａｔ％４时，合金的软磁性能最高，起始磁导率μｉ可达１４．８×１０＾４，讨论了Ｎｂ贪ｘ影响合金磁性的本质。     

TiAl的室温氢致滞后的断裂

ＴｉＡｌ镀Ｎｉ－Ｐ后避免阴极腐蚀。氢化物饱和的试样平面应力断裂韧性ＫＣ（Ｈ）比空气中的ＫＣ值低约２０％。含饱和氢化物试样动态充氢时能发生滞后断裂，这是原子氢引起的。氢致滞后断裂门槛值ＫＩＨ和ＫＣ（Ｈ）的比值约为０．７。     

生产电解二氧化锰用钛合金阳极的抗钝化性能

研究了Ｔｉ－１．５Ｎｉ、Ｔｉ－０．５Ｆｅ、Ｔｉ－１．５Ｎｉ－０．５Ｃｕ、Ｔｉ－１．５Ｎｉ－０．５Ｆｅ－０．３Ｃｕ４种合金在９５℃，４０ｇ／Ｌ Ｈ２ＳＯ４＋８０ｇ／Ｌ ＭｎＳＯ４电解二氧化锰溶液中作阳极时的抗钝化性能。研究表明：以上４种合金都具有比ＴＡ２优异的抗钝化性能，ＴｉＮｉＦｅ的最为优异，在电流密度低于８０Ａ／ｍ＾２时，阳极表面不生成氧化膜，析出相Ｔｉ２Ｎｉ对提高抗钝化性起关键作用。ＴｉＮｉＦ     

新纳米晶软磁合金Fe71.5（CuCrV）7.5Si12B9的磁性能

本文报道新发展的不含Ｎｂ的Ｆｅ７１．５（ＣｕＣｒＶ）７．５Ｓｉ１２Ｂ９纳米晶软磁合金的综合磁性能。直流起始磁导率μｉ＝１０．９×１０＾４；矫顽力Ｈｃ＝０．５６Ａ／ｍ；对应Ｈｍ＝８０Ａ／ｍ的Ｂ８０＝１．０４Ｔ；对应Ｈｍ＝０．０８Ａ／ｍ和ｆ＝０．１和１ＭＨｚ的有效磁导率μｅ＝２．５×１０＾４和０．４×１０＾４；铁损Ｐ２／１００ｋ＝１９５ｋＷ／ｍ＾３；Ｐ２／２００ｋ＝６６４ｋＷ／ｍ＾３；Ｐ２／５００ｋ＝     

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。