[011]多滑移取向铜单晶体的循环形变行为──Ⅰ.循环应力-应变响应

本文在一个较宽的塑性应变幅范围（γpl=1.1×10-4-7．2×10-3）内研究了[011]多滑移取向铜单晶体的循环形变行为.结果表明,[011]晶体的循环形变行为明显不同于[011]和[111]多滑移取向的铜单晶体.[011]晶体具有较低的初始硬化速率,即使在较高的塑性应变幅下,初始硬化速率也无明显变化.［011］晶体的循环应力-应变曲线（CSSC）在所研究的塑性应变幅范围内呈现平台区.CSSC上是否存在平台区,主要由晶体本身的滑移特点和相应的位错反应所决定.疲劳滞后回线形状参数VH在某种程度上可用于确定[011]多滑移铜单晶体的PSB萌生应力     

[■12]双滑移取向铜单晶体的循环应变硬化及饱和

本文在塑性分切应变幅（γpl）为1．3×10-4－7．2×10-3范围内研究了双滑移取向铜单晶体的循环形变行为当γpl＜2×10-3,晶体的初始硬化速率θ0.2较低,几乎与应变幅大小无关。当γpl＞2×10-3,θ0．2随γpl的增加而显著增大．　晶体的循环应力－应变（CSS）曲线在5×10-4＜γpl＜4×10-3范围内呈现一个明显的平台,平台区的范围与单滑移晶体相比明显缩短,但平台区对应的饱和应力相近．和晶体虽然同处于标准取向三角形的001／边上．但其循环形变行为存在明显的差异,可归结为各个滑移系相对于晶体轴的几何位置不同,从而造成不同的滑移形变特征     

CYCLIC STRAIN HARDENING AND SATURATION OF [■12]DOUBLE-SLIP-ORIENTED COPPER SINGLE CRYSTALS

本文在塑性分切应变幅（γpl）为1．3×10-4－7．2×10-3范围内研究了双滑移取向铜单晶体的循环形变行为当γpl＜2×10-3,晶体的初始硬化速率θ0.2较低,几乎与应变幅大小无关。当γpl＞2×10-3,θ0．2随γpl的增加而显著增大．　晶体的循环应力－应变（CSS）曲线在5×10-4＜γpl＜4×10-3范围内呈现一个明显的平台,平台区的范围与单滑移晶体相比明显缩短,但平台区对应的饱和应力相近．和晶体虽然同处于标准取向三角形的001／边上．但其循环形变行为存在明显的差异,可归结为各个滑移系相对于晶体轴的几何位置不同,从而造成不同的滑移形变特征     

双滑移取向Cu单晶的循环形变行为──Ⅰ．循环形变行为SCIEI

在塑性分切应变幅（γｐｌ）为１０^（－４）─１０^（－２）的范围，研究了双滑移取向（［０３４］，［１１７］）和单滑移取向（［１２５］）Ｃｕ单晶的循环硬化及饱和行为．［０３４］晶体的初始循环硬化规律与［１２５］晶体的相似，在γｐｌ小于１０^（－３）的范围，硬化速率（θ＿（０．２））较低，且不依赖于γｐｌ；当γｐｌ＞１０^（－３）时，硬化速率随γｐｌ的增加快速上升．［１１７］晶体在１０^（－４）＜γｐｌ＜５×１０^（－３）范围的初始硬化速率显著高于其它二种晶体．二种双滑移取向晶体在快速硬化之后、均有明显的软化现象．［０３４］晶体的循环应力－应变曲线（ＣＳＳＣ）有一平台区，饱和应力与单滑移晶体的相近，但平台区较短（上限为γｐｌ～４．３×１０^（－３））．［１１７］晶体的ＣＳＳＣ几乎不存在平台区，饱和应力是γｐｌ的单调升函数，与多晶体的ＣＳＳＣ相似．上述循环形变行为与不同滑移系之间的位错反应特点一致．     

CYCLIC DEFORMATION BEHAVIOR OF [011]MULTIPLE-SLIP-ORIENTED COPPER SINGLE CRYSTALS Ⅱ. Surface Slip Features and Deformation Bands

本文系统研究了[011]多滑移取向铜单晶体在不同塑性应变幅下循环饱和后的表面滑移特征.结果表明,[011]多滑移取向铜单晶体的疲劳极限低于[001]多滑移取向铜单晶体.当应变幅γpl≥2.5×10－3时,表面出现两种宏观形变带（DBI和DBII）;它们呈严格的正交关系,其形成可能与循环加载中产生的不可逆晶体旋转密切相关.当应变幅γpl≥5.0×10－3时,表面还出现DBIII形变带,其惯习面为（001）;此类形变带的出现是［011］单晶体在高应变幅下循环达到峰值应力后出现明显循环软化现象的根本原因     

CYCLIC DEFORMATION BEHAVIOUR OF Cu SINGLE CRYSTAL ORIENTED FOR DOUBLE SLIPS Ⅰ. Cyclic Hardening and Saturation

在塑性分切应变幅（γｐｌ）为１０~（－４）─１０~（－２）的范围，研究了双滑移取向（［０３４］，［１１７］）和单滑移取向（［１２５］）Ｃｕ单晶的循环硬化及饱和行为．［０３４］晶体的初始循环硬化规律与［１２５］晶体的相似，在γｐｌ小于１０~（－３）的范围，硬化速率（θ＿（０．２））较低，且不依赖于γｐｌ；当γｐｌ＞１０~（－３）时，硬化速率随γｐｌ的增加快速上升．［１１７］晶体在１０~（－４）＜γｐｌ＜５×１０~（－３）范围的初始硬化速率显著高于其它二种晶体．二种双滑移取向晶体在快速硬化之后、均有明显的软化现象．［０３４］晶体的循环应力－应变曲线（ＣＳＳＣ）有一平台区，饱和应力与单滑移晶体的相近，但平台区较短（上限为γｐｌ～４．３×１０~（－３））．［１１７］晶体的ＣＳＳＣ几乎不存在平台区，饱和应力是γｐｌ的单调升函数，与多晶体的ＣＳＳＣ相似．上述循环形变行为与不同滑移系之间的位错反应特点一致．     

面心立方晶体的循环形变及其位错反应模型 Ⅰ Cu晶体的循环形变

系统地观察了各种不同轴向Cu晶体的循环应力-应变响应及其饱和位错结构.实验结果表明,晶体的宏观循环形变行为和微观位错组态的演变都与晶体的轴向紧密相关.在一些轴向位于标准取向三角形内的单滑移晶体中观察到明显的多滑移现象;其循环形变行为和饱和位错结构都与相邻的双滑移或多滑移晶体有许多相似之处.     

Cu双晶的循环形变行为与疲劳裂纹萌生：Ⅰ.循环形变行为和滑移形貌

在切应变幅γpl≈1066×10-4至9．1×10-3s范围内，研究了四种Cu双晶的循环形变行为,实验结果表明，对于含两单滑移取向组元晶体的三种子行晶界双晶，其循环形变行为表现出和单滑移取向Cu单晶类似的特征，循环应力一应变（CSS）曲线上存在一平台区，但平台应力都高于单滑移取向Cu单晶的典型值（28MPa），且各有所差别对于含一单滑移和一双滑移组元晶体的垂直晶界双晶，CSS曲线上没有明显的平台，并且发现曲线与Cu多晶的CSS曲线非常类似表面形貌观察表明，上述循环形变行为与由于晶界约束而导致的双滑移或多沿移现象以及开动沿移系的位错反应强度密切相关     

垂直晶界钢双晶体的循环形变行为

本文通过对取向近垂直晶界铜双晶体进行塑性应变控制循环变形,在表面滑移形貌及饱和位错组态观察的基础上,研究了其循环应力－应变响应．结果表明该铜双晶体循环应力－应变（CSS）曲线具有两个饱和轴向应力基本不变的平台区．即在塑性应变范围1．80×10-4－1．35×10-3对应于饱和应力幅62—64MPa及在塑性应变范围2．04×10-3—2．56×10-3对应于饱和应力幅70—71MPa．讨论了组元晶体的相对取向对其滑移形貌、饱和位错组态及CSS曲线的影响。     

垂直晶界铜双晶体的循环形变行为

本文通过对取向近垂直晶界铜双晶体进行塑性应变控制循环变形,在表面滑移形貌及饱和位错组态观察的基础上,研究了其循环应力－应变响应．结果表明该铜双晶体循环应力－应变（CSS）曲线具有两个饱和轴向应力基本不变的平台区．即在塑性应变范围1．80×10-4－1．35×10-3对应于饱和应力幅62—64MPa及在塑性应变范围2．04×10-3—2．56×10-3对应于饱和应力幅70—71MPa．讨论了组元晶体的相对取向对其滑移形貌、饱和位错组态及CSS曲线的影响。     

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.