Cu－Ni－Al单晶的分形断裂与相变增韧

测定了Ｃｕ－Ｎｉ－Ａｌ单晶在２０—１２０℃温度范围的断裂韧性ＫＣ和断裂表面的分形维数Ｄｆ．裂纹前沿应力诱导相变使母相有较高的ＫＣ．在单一断裂机制下，ｌｎＫＣ与Ｄｆ之间有简单的线性关系：脆性断裂时斜率为正，韧性断裂时斜率为负．由断裂微观机制与分形概念对上述结果进行分析讨论．     

非晶态Fe_(46)Ni_(32)V_2Si_(14)B_6合金的分形断裂

测定了结构弛豫阶段退火温度ＴＲ对非晶态Ｆｅ４６Ｎｉ３２Ｖ２Ｓｉ１４　Ｂ６合金条带室温断裂韧性（Ｋｃ）的影响．ＴＲ小于２００℃时,ＫＣ大致不变,平均值约８ＭＰａｍ１／２;随着ＴＲ由２００℃增加至３５０℃,ＫＣ值逐渐下降至２ＭＰａｍ１／２;相应地断裂剖面形貌由不规则特征（分形的）逐渐变为平直的或光滑的特征．用垂直截面法测定断裂剖面裂纹轮廓线的分形维数Ｄｆ．实验结果表明,在准二维脆性断裂条件下,Ｋｃ值与分形维数增量的平方根成正比,并讨论不同结构弛豫阶段断裂特征长度ａｃ与断裂机制     

非晶Fe—B—Si软磁合金损耗谱的分形结构

研究了Ｆｅ－Ｂ－Ｓｉ非晶软磁合金的铁芯损耗谱Ｐ（ｆ），发现Ｐ（ｆ）具有分形结构，讨论了热处理工艺对分形维数Ｄｆ的影响。     

形变氮化08F钢冲击断口的分形研究

利用垂直截面法测量了０８Ｆ钢经不同形变氮化复合后冲击断裂表面的分形维数。结果表明，材料的冲击能Ａ和沿裂纹扩展方向剖面Ｋｏｃｈ曲线的分形维数Ｄ地均随表变量的增而增加。分形维维数Ｄ与ｌｎＡ之间呈正变化的关系，且满足下列关系式：ｌｎＡｋ＝４９．４３ＫＦ－５１．４４。     

恒导磁合金损耗谱的分形结构

研究了恒导磁合金的铁芯损耗谱Ｐ（ｆ），发现Ｐ（ｆ）只有分形结构讨论了感生各向异性能Ｋ_ｕ对分形维数Ｄ_ｆ的影响．     

非晶Fe－B－Si软磁合金损耗谱的分形结构

研究了Ｆｅ－Ｂ－Ｓｉ非晶软磁合金的铁芯损耗谱Ｐ（ｆ），发现Ｐ（ｆ）具有分形结构。讨论了热处理工艺对分形维数Ｄｆ的影响。     

少量硼对Fe—Cu纳米粉粒固溶度的影响

用化学还原法制备了Ｆｅ－Ｃｕ过饱和固溶合金粉。Ｆｅ－Ｃｕ纳米粉中含有少量硼可扩展ｆｃｃ相的成分范围。合金粉体中Ｆｅ和Ｃｕ的原子比达到４：１时，主相仍保持ｆｃｃ结构，ｆｃｃ相区的范围可超过采用机械合金化法制备的Ｆｅ－Ｃｕ合金。对样品的退火处理研究证明了Ｆｅ－Ｃｕ系过饱和固溶合金的ｆｃｃ相相当稳定。     

分形用于金属断裂研究的力学量选择问题SCIEI

本文给出了一个描述临界裂纹扩展力的分形模型．指出：断口的分形结构是裂纹扩展过程的产物，因此将分形用于金属断裂研究时，所选择的力学量应该能表征裂纹扩展过程所具有的耗散性；弹性断裂力学的ＫＩｃ、ＪＩｃ等裂纹起裂韧性与断口的分形维数是不相容的．     

蒸发—气体—聚集制备的Co—Ag颗粒膜微观结构与巨磁电阻特性

基于溅射－气体－聚焦（ＳＧＡ）形成纳米金属颗粒的原理,提出了蒸发－气体－聚集（ＥＧＡ）共沉积制备Ｃｏ－Ａｇ颗粒膜的新方法,并利用该方法制备了系列Ｃｏ－Ａｇ颗粒膜样品,ＴＥＭ／ＥＤ分析表明;制备态样品Ｃｏ颗粒被Ａｇ原子所包裹,能有效地阻止颗粒的表面氧化与团聚,薄膜无需经过热处理即可形成Ｃｏ与Ａｇ的相分离,其结构为ｆｃｃ－Ｃｏ和ｆｃｃ－Ａｇ非均匀相多晶共存形态;与Ｃｏ大块材料相比,薄膜中Ｃｏ颗粒晶格常     

纳米稀土金属Gd的磁性及分形特征

采用惰性气体保护蒸发凝聚技术制备出粒径为４～１５ｎｍ的稀土金属Ｇｄ微粉（ｎｍＧｄ）。经振动样品磁强计测试，表明ｎｍＧｄ微粉在某一特征粒径ｄｃ时磁化率χ取得最小值。利用小角Ｘ射线散射方法分析了ｎｍＧｄ微粉的三维生长分形特征，表明ｎｍＧｄ微粒聚集体系呈质量分形，制备气压越小则分维系数Ｄｆ越小。微粒生长模型是扩散限制聚集（ＤＬＡ）与扩散限制团聚聚集（ＤＬＣＡ）模型共存，相应这两个模型阶段的分维系数Ｄｆ存在一特征粒径ｄｆ。根据纳米微粒理论对ｎｍＧｄ微粉体系的量子尺寸效应的特征尺寸ｄｑ进行了估算，并就三种特征粒径ｄｃ、ｄｆ和ｄｑ进行了分析和比较     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.