添加元素对稀土粘结磁体退磁曲线方形度的影响

采用快淬法制备镨基(Nd,Pr)10.5(Fe,Co)83.5-xMxB6(M=Zr,Nb,Ti)系列粘结磁体,研究添加Zr、Nb和Ti等元素对快淬合金显微结构和磁性能的影响.(Nd,Pr)10.5(Fe,Co)83.5B6合金中适量添加Zr、Nb和Ti元素能有效细化合金晶粒,获得细小、均匀的晶粒,平均晶粒尺寸为50～70 nm.添加Zr、Nb和Ti元素的粘结磁体,由于晶粒细化和非磁性相对磁畴畴壁钉扎的共同作用,Hk/Hcj值大幅度增加,退磁曲线方形度得到明显改善,磁性能也显著提高.在Zr、Nb和Ti3种元素中,Zr对细化晶粒和提高磁性能的效果最好.含1％Zr(原子分数)的(Nd,Pr)10.5(Fe,Co)82.5Zr1B6合金薄带晶粒细小、均匀,平均尺寸约为60 nm,其粘结磁体退磁曲线方形度最好,Hk/Hcj值达到了39.9％,剩磁Br为0.675 T,内禀矫顽力Hci为616 kA/m,最大磁能积(BH)m为77 kJ/m3.     

Nb元素对纳米晶（Nd，Pr）FeB／α-Fe复合永磁合金显微结构与磁性能的影响

添加Nb元素会使(Nd,Pr)FeB/α-Fe纳米晶复合永磁合金的平均晶粒尺寸显著减小.用AFM观察快淬(Nd,Pr)10.5Fe81.5-xNbxCo2B6(x(at%,下同)=0.0,0.5,1.0,1.5,2.0,2.5,3.0)合金条带自由表面的显微结构,晶粒平均直径从不含Nb的(Nd,Pr)10.5Fe81.5Co2B6合金的175 nm减小到含2 at%Nb的(Nd,Pr)10.5Fe79.5Nb2Co2B6合金的68 nm,晶粒平均直径细化了61%;当Nb超过2 at%后,Nb含量的增加对晶粒的细化作用明显减弱,含3 at%Nb的合金平均晶粒直径为63 nm,比含2 at%Nb仅细化了7.3%.含2 at%Nb的(Nd,Pr)10.5Fe79.5Nb2Co2B6合金,粘结磁体磁性能达到最佳值,Bτ=0.665 T,Hci=748 kA·m-1,(BH)m=73 kJ·m-3.Nb元素含量在2 at%Nb以下时,合金晶粒粗大,磁性能较低;超过2 at%后,富集在晶界处的富Nb晶间相加厚,晶粒间的交换作用和剩磁增强效应减弱,合金的内禀矫顽力虽然增加,但剩磁Bτ和最大磁能积(BH)m降低.     

Ti添加对快淬Pr基永磁合金磁性能与显微结构的影响

采用快淬法制备了Pr基(Nd,Pr)10.5Fe81.5-xTixCo2B6(x=0.0,1.0,2.0,3.0,4.0,5.0)系列粘结磁体,研究了添加Ti元素对快淬合金显微结构和磁性能的影响。Ti元素能有效细化合金的晶粒,添加3at%Ti的合金,晶粒细化到约70nm,且大小均匀;添加量超过3at%,晶粒进一步细化,但均匀性变差。含Ti3at%的(Nd,Pr)10.5Fe78.5Ti3Co2B6合金,粘结磁体磁性能达到最佳值,Br=0.655T,Hci=681kA/m,(BH)m=68kJ/m3。Ti元素低于3at%,合金晶粒粗大,磁性能较低;超过3at%后,富Ti的晶间相加厚,晶粒间的交换作用和剩磁增强效应减弱,且晶粒大小不均匀,合金的内禀矫顽力虽然增加,但剩磁Br和最大磁能积(BH)m降低。     

Dy元素对纳米复合(Nd,Pr)_(10.5-x)Dy_xFe_(83.5)B_6合金磁性能与显微结构的影响（英文）EI北大核心CSCD

采用快淬法制备了镨基(Nd,Pr)10.5-x Dyx Fe83.5B6(x=0.0,0.5,1.0,1.5,2.0,2.5)系列粘结磁体,研究了Dy元素添加对快淬合金显微组织结构、磁性能及快淬薄带热稳定性的影响。与Nd2Fe14B相比,硬磁相Dy2Fe14B具有较高的磁晶各向异性场HA和较低的饱和磁极化强度Js,因此,Dy元素添加能显著提高合金的内禀矫顽力Hcj,但会降低合金的剩磁Br。Dy元素替代Nd/Pr元素,增强了快淬薄带的热稳定性,提高了晶化退火温度。较高的晶化退火温度,使快淬薄带中已经形成的微晶更容易长大,形成一些粗大晶粒,降低了粘结磁体的磁性能。1.0%是较佳的Dy元素添加量,(Nd,Pr)9.5Dy1Fe83.5B6合金快淬粘结磁体的最大磁能积(BH)max为71.6 k J/m3,剩磁Br为0.638 T,内禀矫顽力Hcj为611 k A/m。     

Dy元素对纳米复合(Nd,Pr)_(10.5-x)Dy_xFe_(83.5)B_6合金磁性能与显微结构的影响（英文）

采用快淬法制备了镨基(Nd,Pr)10.5-x Dyx Fe83.5B6(x=0.0,0.5,1.0,1.5,2.0,2.5)系列粘结磁体,研究了Dy元素添加对快淬合金显微组织结构、磁性能及快淬薄带热稳定性的影响。与Nd2Fe14B相比,硬磁相Dy2Fe14B具有较高的磁晶各向异性场HA和较低的饱和磁极化强度Js,因此,Dy元素添加能显著提高合金的内禀矫顽力Hcj,但会降低合金的剩磁Br。Dy元素替代Nd/Pr元素,增强了快淬薄带的热稳定性,提高了晶化退火温度。较高的晶化退火温度,使快淬薄带中已经形成的微晶更容易长大,形成一些粗大晶粒,降低了粘结磁体的磁性能。1.0%是较佳的Dy元素添加量,(Nd,Pr)9.5Dy1Fe83.5B6合金快淬粘结磁体的最大磁能积(BH)max为71.6 k J/m3,剩磁Br为0.638 T,内禀矫顽力Hcj为611 k A/m。     

Dy元素对快淬(Nd, Pr)FeB合金的磁性能和晶化转变温度的影响

采用快淬法制备了镨基(Nd,Pr)10.5-xDyxFe83.5B6 (x=0,1,2)系列粘结磁体,测定了快淬条带晶化转变温度,研究了添加Dy元素对快淬合金条带晶化转变温度的影响。合金中添加Dy元素,快淬态条带晶化过程中非晶态向晶态转变的开始温度及结束温度提高,转变的温度区间增大。由于热稳定性的提高,条带晶化退火需要采用较高的温度。添加2%Dy元素的(Nd,Pr)8.5Dy2Fe83.5B6合金,最佳退火温度比 (Nd,Pr)9.5Dy1Fe83.5B6和(Nd,Pr)10.5Fe83.5B6分别提高了15和30 ℃。添加Dy元素的粘结磁体,内禀矫顽力Hcj增加,但剩磁Br下降,实验制备的(Nd,Pr)9.5Dy1Fe83.5B6合金磁体的磁性能为Br=0.638 T,Hcj=611 kA/m,(BH)m=71.6 kJ/m3     

双相纳米晶Nd10Fe75Co5Zr3Cr0．5B6．5磁体的研究

采用熔体快淬及晶化热处理工艺制备Nd10Fe75Co5Zr3Cr0.5B6 5纳米晶合金.快淬薄片(17m·s-1)在710℃,4 min晶化处理后,晶粒尺寸为50 nm～60 nm.该快淬薄片经710℃,4min晶化处理后制成的粘结磁体的磁性能为Br=0.67 T,JHc=707 kA·m-1和(BH)max=74 kJ·m-3.     

Nb和Zr对（Nd，Pr）2Fe14B／α-Fe磁体晶化行为和磁性能的影响

采用熔体快淬及晶化退火工艺制备了纳米双相（Nd，Pr）2Fe14B／α-Fe型磁体，研究了Nb和Zr的添加对磁体磁性能、微观结构和晶化行为的影响。结果表明：添加Nb和Zr可提高α—Fe相的晶化温度，抑制α—Fe的析出和长大，避免亚稳相的形成，从而提高硬磁相的体积百分比。Nb和Zr复合添加能细化晶粒，增强硬磁相和软磁相问的交换耦合作用，显著提高纳米晶双相永磁合金的磁性能。合金（Nd，Pr）2Fe14B／α-Fe经过最佳热处理后，磁性能达到Br=1．10T，iHc=534．2kA／m，（BH）max=143．6kJ／m^3。     

双相纳米晶Nd10.1Fe（82.2-x）Co5Zr2.7Bx永磁材料的研究

采用熔体快淬及退火方法制备了Nd10.1Fe(82.2-x)Co5Zr2.7Bx(x=6.2,6.5,6.7,7)纳米晶双相永磁体.结果表明,优化B的含量,可使晶粒细化、均匀,并对其磁性能有一定的影响,在x=6.7时,快淬速度为16m·s-1,有显著的剩磁增强作用,各向同性剩磁比Mr/Ms=0.758,并且Nd10.1Fe(82.2-x)C05Zr2.7Bx粘结磁体出现最佳性能,其剩磁和最大磁能积分别为Br=0.72 T,(BH)max=85.0 kJ·m-3.     

Sm-Fe-N系永磁体

Sm Zr Fe Co B N磁粉与粘结磁体〔1〕 　使用(Sm0 7Zr0 3) (Fe0 8Co0 2 ) 9B0 1Nx 磁粉制造的各向同性磁体 ,获得了Br =1 0 7T(10 7kG)、HCJ =780kA/m(9 8kOe)和 (BH) max =180kJ/m3(2 2 6MGOe)的磁特性。这一磁特性作为各向同性磁体可以认为是当前的最高水平 ,这也是头一次实现了通过高度的饱和磁化与晶粒细化而得到的剩磁增强效应的最充分利用。并且能够依靠调整Sm/Zr成分比来控制剩磁与矫顽力的大小 ,因此 ,当前正在开发Br =1～ 1 0 7T、HCJ =6 40～ 880kA/m、(BH) max =16 0～ 180kJ/m3各种特性范围的磁体粉末。…     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.