热处理工艺对新型无磁辊材料硬度及析出相的影响

针对新型连铸用无磁辊材料成分,设计不同的热处理试验方案并测得其硬度,并采用SEM、TEM、图像统计分析等方法,观察并计算无磁辊材料经不同热处理后析出相的形貌及尺寸,从而建立新型无磁辊材料热处理工艺与硬度、析出相尺寸之间的关系。结果表明:660、710、760、810℃温度下,材料的硬度随着时效时间延长先上升,达到峰值后下降,其析出相γ’不断粗化;860℃下时效,材料硬度趋于平稳且较低。在760℃下时效12 h后,材料硬度最高达到321HBS,γ’相平均尺寸在30.4 nm,且弥散分布在基体上。     

热处理对Fe-6.5wt%Si合金冷轧薄板组织及磁性能的影响

Fe-6.5wt%Si合金具有优异的软磁性能,但由于有序相的出现,室温塑性低,很难用传统的轧制方法制备薄板。研究了一种特殊的轧制方法和相应的热处理工艺,冷轧出了厚度为0.03～0.05mm的该合金薄板。在制备过程中,通过观察热处理前后材料显微组织,硬度和结构的变化,研究热处理对材料塑性的影响;通过观察冷轧薄板热处理前后磁性能的变化,研究热处理对磁性能的影响。研究表明,通过采取不同的热处理手段,可以抑制部分有序相的生成,提高材料塑性或者生成有序相,提高材料磁性能。     

热处理温度对纳米晶Ni0.35Zn0.65Fe2O4吸波性能的影响

采用溶胶-凝胶自燃烧法制备了Ni0.35 Zn0.65 Fe2 O4纳米晶,将其分别在550、800和1050℃下热处理2 h,利用XRD、VSM以及微波矢量网络分析仪对产物的晶体结构、电磁性质及其在GHz波段的吸波性能进行了表征.结果表明,自燃烧后即已形成尖晶石相;随着热处理温度的升高,平均粒径从25 nm增至52 nm,均为单畴颗粒.在0.1～1.5 GHz的测试频率范围内,热处理后的纳米晶样品的比饱和磁化强度和矫顽力随温度的升高而增加,从而提高了其自然共振频率,拓宽了其吸收频带.热处理后样品的ε'、ε"、tgδe以及μ'、μ"、tgδm值均随热处理温度的升高而增大,其中以1050℃下热处理样品的电损耗和磁损耗性质最佳,其μ'值大于1.6,且随频率的升高而降低;μ"值大于1.0,且随频率的升高而增大,频率特性良好,在所测频段内是一种理想的电磁波吸收材料.     

铋取代钇铁石榴石/环氧树脂磁光复合薄膜的共沉淀制备

报道了铋取代钇铁石榴石(Bi-YIG)/环氧树脂磁光复合薄膜的制备工艺.经透射电镜(TEM)分析,Bi-YIG颗粒尺寸随热处理温度和时间的降低而显著减小.通过详细讨论热处理条件对薄膜Faraday旋转角(θF)和光散射系数(S)的影响,确定最佳热处理条件为650℃下保温4 h.得到的复合薄膜,在激光波长λ=633 nm下测量,拥有最大磁光优质(θF/S),其达到4.7°.     

FeCo软磁合金热处理后的微观组织和磁性能

研究了氢气热处理对FeCo-2V软磁合金磁性能和相结构的影响以及合金在不同温度环境下的磁性能变化。结果表明:经氢气热处理后,合金平均晶粒尺寸增大至近200μm,α相含量增多,磁畴平均厚度增加了一倍左右,达到2μm;经开路和闭路磁性能测试,合金各项软磁性能均大幅提高;合金在-70~180℃的温度环境下,其Ms仅下降1%,而初始磁导率则有大幅提高,此外合金在极端温度环境下,仍具有较好的温度稳定性。     

不同相厚度下对SrFe12O19/α-Fe纳米复合双层膜的微磁学模拟

采用三维模拟软件OOMMF对铁氧体纳米复合双层膜SrFe₁₂O₁₉/α-Fe进行微磁学模拟研究。结果显示,固定硬磁相厚度分别为10、15和20 nm,逐渐增大软磁相厚度,复合材料均表现出剩磁增强效应,计算(BH)_max分别在软磁相厚度L_s=5 nm,6 nm和6 nm时取得最大值165.57,136.39和117.32 kJ/m³,是目前单相锶铁氧体的(BH)_max(40 kJ/m³)的3~4倍左右。在软磁相厚度相同的条件下,随着硬磁相厚度的增加,复合材料的剩磁、最大磁能积逐渐减小,矫顽力略有增大,最佳的(BH)_max在硬磁相厚度为10 nm时取得。磁矩反转过程随着硬磁相厚度的变化而表现出不同的特点。     

热处理对<110>取向Tb-Dy-Fe-Al合金组织和性能的影响

采用区熔定向凝固方法制备了<110>取向的Tb0.3Dy0.7(Fe1-xAlx)2(x=0,0.05,0.10,0.15)超磁致伸缩合金,在真空管式炉氩气保护条件下,对合金进行930℃×2 h的热处理,研究了热处理对于不同含量Al元素替代合金的微观组织、磁致伸缩性能和力学性能的影响。结果表明:热处理不改变Tb0.3Dy0.7(Fe1-xAlx)2合金样品定向凝固形成的<110>轴向择优取向,热处理后的合金棒样品依然保持MgCu2型立方Laves相和部分稀土相结构,没有新相对应的衍射峰产生。热处理后Tb0.3 Dy0.7(Fe1-xAlx)2合金的片层组织退化,随着Al元素含量的增加,基体内的析出相形态和分布不断发生变化。当Al的添加量为x=0.05和x=0.15时,热处理后合金的磁致伸缩性能下降,饱和磁致伸缩分别为817×10-6,571×10-6。Al的添加量x=0.10时,热处理在不降低合金饱和磁致伸缩的同时可以显著提高其压缩强度及低场动态响应。     

纳米晶富铁Fe-Nb-Nd-B合金的微细组织与磁特性

由软磁相ｂｃｃ Ｆｅ与硬磁相Ｎｄ2 Ｆｅ14 Ｂ组成的纳米复合磁体的磁特性 ,根据模拟计算的结果 ,在ｂｃｃ Ｆｅ相的体积分率增加到 60 %和粒径细化到 10ｎｍ左右时 ,其 (ＢＨ) ｍａｘ 可超过 4 0 0ｋＪ/ｍ3。高浓度Ｆｅ的Ｆｅ (Ｚｒ ,Ｎｂ) (Ｎｄ ,Ｐｒ) Ｂ非晶合金 ,通过热处理获得的纳米复相组织 ,其晶粒粒径主要取决于热处理条件 ,因此 ,为了获得良好的硬磁特性 ,有必要实现热处理条件的最佳化。因此 ,日本东北大学金属材料研究所等单位的研究人员 ,研究了富铁的Ｆｅ Ｎｂ Ｎｄ Ｂ非晶合金经过最佳热处理后的微细结晶组织及磁特性。研…     

<110>取向Tb-Dy-Fe超磁致伸缩材料的热处理工艺

采用区熔定向凝固方法制备了<110>轴向择优取向的Tb0.3Dy0.7Fe2超磁致伸缩合金,在真空管式炉氩气保护条件下,对合金进行不同温度和时间的热处理,研究了不同处理时间、处理温度、冷却条件对该合金取向、组织、磁致伸缩性能以及力学性能的影响。结果表明:热处理不改变定向凝固形成的轴向择优取向;经930℃×2 h热处理后,网状的富稀土相基本转变为球状并均匀分布在基体相内,定向凝固形成的片层状组织发生退化,减小了REFe2相的磁畴在磁场中转动的阻力。细小的球状富稀土相均匀弥散分布在基体相内,减少了应力集中,因此提高了磁致伸缩性能和压缩强度;定向凝固Tb-Dy-Fe合金采用930℃×2h热处理后随炉冷却的工艺可以获得良好的综合性能,其饱和磁致伸缩为1226×10-6,压缩强度为256 MPa。     

热处理温度对电沉积纳米晶Ni-Fe合金箔的组织与性能的影响

在氢气气氛下对电沉积法制备的粒径10 nm左右的纳米晶Ni-Fe合金箔进行中温热处理(200、300、400和500 ℃);利用扫描电镜观察合金箔的截面组织形貌;采用X射线衍射仪检测合金箔的晶体结构和粒径;利用软磁材料直流磁性测试装置测试合金箔的直流磁特性.结果表明:在氢气气氛中,300 ℃热处理保温1 h后,合金箔的粒径维持在10 nm左右,且直流磁性能最好,最大磁导率达到56.4 mH/m,饱和磁感应强度为1.56 T,矫顽力降至15.0 A/m.     

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。