热处理及SmCo磁性层对TbDyFe薄膜磁致伸缩性能的影响

研究了SmCo薄膜的复合及热处理对TbDyFe薄膜磁性及磁致伸缩性能的影响。XRD分析表明制备态的TbDyFe薄膜为非晶态，在450℃退火后，样品仍保持非晶态结构。退火处理减少了薄膜的垂直各向异性，并且退火热应力有利薄膜的易磁化轴转向膜面，从而提高了薄膜的磁导率和TbDyFe薄膜低场下的磁致伸缩值。磁控溅射的SmCo薄膜有良好的软磁性能，它的复合也能有效地增强TbDyFe薄膜的低场磁致伸缩性能。     

NdFeB薄膜制备及对TbFe薄膜磁致伸缩性能的影响

本文采用磁控溅射镀膜技术,制备NbFeB、TbFe单层及TbFe/NbFeB复合薄膜。通过设计正交试验,优化溅射工艺参数。采用振动样品磁强仪、X射线衍射对不同热处理温度处理的NbFeB薄膜的磁学性能、晶体结构进行了研究,并采用电容位移测量法对TbFe薄膜和TbFe/NbFeB复合薄膜的磁致伸缩系数进行测量。研究结果表明,NbFeB薄膜和TbFe薄膜为内易磁化方向,在低于400℃温度下真空热处理,薄膜保持非晶态,显现较好的软磁性能。与TbFe薄膜复合,可以大大降低薄的矫顽力,其低场磁致伸缩性能优于TbFe单层薄膜,这为提高TbFe薄膜的低场磁致伸缩性能的研究提供了一条新途径。     

磁控双靶共溅射磁致伸缩TbFe薄膜的研究

采用直流磁控双靶共溅射方法,在玻璃基片上制备了非晶态的TbFe磁致伸缩薄膜,研究了溅射功率、工作气压等工艺参数对薄膜成分的影响.研究结果表明:当溅射功率从20W增加到100W时,TbFe薄膜中Tb含量从35.77at%增加到44.54at%;工作气压从0.2 Pa增加到1.0 Pa时,11)Fe薄膜中Tb含量从38.02at%增加到44.1at%.重点研究了真空退火处理对TbFe薄膜磁性及磁致伸缩性能的影响.结果表明,真空退火处理有利于提高平行于膜面的饱和磁化强度和磁导率;350℃真空退火60 min,在外加磁场为5 kOe条件下,TbFe薄膜的磁致伸缩系数可达到351x10-6.     

超磁致伸缩TbFe/FeAI多层膜的研究

采用直流磁控溅射法制备了TbFe/feAl超磁致伸缩多层膜,研究了FeAl薄膜的复合对TbFe薄膜磁性能以及热处理温度对TbFe/FeAl磁致伸缩多层膜磁致伸缩系数的影响.结果表明.ThFe层与FeAl层之间的交换耦合作用以及热处理能明显提高薄膜的软磁性能和磁致伸缩性能;与TnFe单层膜相比,TbFe/FeAl多层膜水平方向的矫顽力从59.2kA·m-1降低到29.6kA·m-1;经最佳退火处理(350℃×60min),获得了较低的饱和磁场强度和矫顽力,分别为H =96kA·m-1和,H =16kA·m-1;外加磁场400kA·m-1时,ThFe/FeAl磁致伸缩多层膜磁致伸缩系数可达574×10-6.     

Sm-Fe系薄膜悬臂板磁致伸缩行为的有限元模拟分析

以离子束溅射沉积(IBSD)法制备的Sm-Fe系超磁致伸缩薄膜悬臂板为研究对象,通过ANSYS有限元分析法,对超磁致伸缩薄膜/盖玻片衬底悬臂板自由端挠度值的大小进行模拟计算,并模拟Sm-Fe薄膜、Sm-Fe/Fe复合膜的内部磁化状态.结果表明:在薄膜与衬底厚度比较小的情况下,悬臂板端点挠度值随薄膜厚度的增加而线性增加,且与衬底厚度近似成二次抛物线关系,有限元分析结果与实测情况吻合较好;Sm-Fe单层膜内部磁力线分布较均匀;在Sm-Fe/Fe复合膜中,由于Fe膜的负磁场效应,使Sm-Fe膜内的磁力线分布出现不均匀的现象,且磁感应强度比Sm-Fe单层膜小.     

超磁致伸缩TbFe/FeAl多层膜的研究

采用直流磁控溅射法制备了TbFe/FeAl超磁致伸缩多层膜,研究了FeAl薄膜的复合对TbFe薄膜磁性能以及热处理温度对TbFe/FeAl磁致伸缩多层膜磁致伸缩系数的影响。结果表明,TbFe层与FeAl层之间的交换耦合作用以及热处理能明显提高薄膜的软磁性能和磁致伸缩性能;与TbFe单层膜相比,TbFe/FeAl多层膜水平方向的矫顽力从59.2kA·m^-1降低到29.6kA·m^-1;经最佳退火处理（350℃×60min）,获得了较低的饱和磁场强度和矫顽力,分别为Hs=96kA·m^-1和JHc=16kA·m^-1;外加磁场400kA·m^-1时,TbFe/FeAl磁致伸缩多层膜磁致伸缩系数可达574×10^-6。     

粉末冶金粘结磁致伸缩材料

粘结磁致伸缩材料是由Terfenol-D粉末与树脂粘结剂混合固化而成。TbDyFe粉末颗粒的大小,树脂的粘度系数,树脂的配比及磁场中的取向都对粘结磁致伸缩材料的磁致伸缩性能产生较大的影响。试验结果表明,TbDyFe粉末颗粒尺寸的大小对粘结磁致伸缩材料的磁致伸缩性能影响较大。制造较好性能的粘结磁致伸缩材料所需TbDyFe粉末颗粒尺寸应控制在＜280μm。同时,材料在压型过程中由于外加磁场而使磁畴取向,从而提高了磁致伸缩性能。     

功率对磁控溅射TbDyFe薄膜磁致伸缩性能的影响

采用直流磁控溅射工艺制备TbDyFe磁致伸缩薄膜，通过考察薄膜成分及其微结构，分析研究了溅射功率对薄膜磁致伸缩性能的影响。结果表明，同一薄膜内部成分相当均一，但不同溅射功率条件下的薄膜成分相异。溅射功率较低，薄膜内部微柱状体结构导致了磁各向异性的产生，磁致伸缩性能下降；溅射功率提高到120W，微柱状体结构消失，薄膜内部趋于均一连续，磁致伸缩性能较好。     

退火磁场施加方式对Tb0.3Dy0.7Fe1.95合金磁伸性能的影响

研究了磁场退火时磁场施加方式对《110》取向Tb0.3Dy0.7Fe1.95定向凝固多晶合金磁致伸缩性能的影响.退火磁场强度为1T,保温时间30 min.研究表明,在623K下采用垂直磁场且冷却时保持磁场的方式退火,可改善综合磁伸性能,如提高饱和磁致伸缩系数并使低场磁致伸缩系数基本不变,提高最大动态磁致伸缩系数且其对应的磁场基本不变.冷却阶段撤去磁场会减弱磁场退火的作用,而平行磁场退火的效果与垂直磁场相反.     

压应力对Sm-Fe-B薄膜磁致伸缩性能的影响

压应力对Sm-Fe-B磁致伸缩性能的改善有重要影响,但是其大小对磁致伸缩特性变化趋势的研究很少,而且还未见到压应力对磁各向异性影响的报道。本文利用特制夹具,使玻璃衬底在镀膜过程中受到不同应力作用,镀膜结束后,当玻璃衬底从夹具取下后,利用其恢复到原来状态,可以对稀土Sm-Fe-B薄膜产生压应力作用。通过调整夹具使衬底具有不同的预应力,可得到受到玻璃衬底不同压应力大小作用的薄膜样品。利用LK-G150激光微位移传感器与交变梯度磁强计（AGM）分别测试薄膜悬臂梁自由端偏转量与磁滞回线,以研究具有不同压应力对薄膜的磁致伸缩性能的影响,并且利用磁力显微镜（MFM）测试了薄膜样品垂直表面的磁畴分布情况。实验结果表明：受到压应力作用的薄膜易磁化轴都位于膜面内,以面内各向异性为主,磁畴结构基本分布在面内。随着压应力的增加,易磁化轴由膜面内的短轴转向膜面内的长轴,这一转变有利于器件的设计,但是磁畴在垂直膜面方向略有提高,薄膜的低场磁致伸缩性能也随着压应力的增大而有显著提高。     

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.