Magnetic properties and microstructures of Fe-Cr-10 wt% Co-M (M= Si/Ti/Ni/Mo/Ge/Ta) permanent magnet alloys

Effect of alloying elements and heat treatments on magnetic properties and microstructures of Fe-Cr-10 wt% Co alloys was studied by magnetic measurements and transmission electron microscopy (TEM). Among the alloying elements tried, it was found that only Si and Ti can greatly improve the hard magnetic properties of the Fe-Cr-Co alloys. An Fe-10Co-26Cr alloy added with 0.5 wt% Si-0.5 wt% Ti showed the best combination of magnetic properties of H_c = 43 kA/m.B_r = 1.42 T, (BH)_m = 41 kJ/m³.The variation in magnetic properties was correlated to quantitative microstructural features, particle size and aspect ration. It was found that for alloys of the same composition, H_c is determined by shape anisotropy induced by magnetic aging.     

合金元素对钢中NbC异质形核影响的第一性原理研究

为了探索不同合金元素对Nb C异质形核的影响,本文利用第一性原理研究了合金元素X(X=Cr,Mn,Mo,W,Zr,V,Ti,Cu和Ni)对ferrite(100)/Nb C(100)界面性质的影响,并且分析了上述合金元素掺杂前后界面的黏附功、界面能和电子结构.研究结果表明,Cr,V和Ti掺杂的界面具有负的偏聚能,说明它们容易偏聚到ferrite/Nb C界面,但Mn,W,Mo,Zr,Cu和Ni却难以偏聚到此界面.当Mn,Zr,Cu和Ni取代界面处的Fe原子后,界面的黏附强度降低,即这些合金减弱铁素体在Nb C上的形核能力.然而Cr,W,Mo,V和Ti引入界面后,其黏附功比掺杂前的界面要大,且界面能均降低,即提高了界面的稳定性.因此,W,Mo,V和Ti,尤其是Cr,能够有效地促进铁素体形核和细化晶粒.电子结构分析表明,Zr和Cu引入界面后,界面处的Zr,Cu原子和C原子的相互作用变弱;然而Cr和W引入界面后,Cr,W和C原子之间形成了很强的非极性共价键,提高了ferrite/Nb C界面的结合强度.     

合金工具钢的X射线荧光光谱分析

本文介绍了用X射线荧光光谱仪测量合金工具钢中Mn,Cr,V,W,Ti,Nb,Co,Zr,Ni,Mo,S,P,Si和Cu十四个元素的方法,度样经砂轮抛光酒精棉擦拭后直接测量,结果与内控标样吻合,方法的精密度（n=8)除W,Tr,Nb和Zr外,大多数元素在0．13－9．59％,适应铬钒钢,锰钢,模具钢,中低合金钢等多种钢种的分析。     

Interaction of oxygen and nitrogen with clean transition metal surfaces

The interaction of O and N with evaporated films of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Re, Fe, Ni, Cu, and Ag has been analysed in the range 10^?3 to 10^?10 mbar and 77 to 370 K with respect to the processes prevailing in various metal-gas systems. The shape of typical energy-reaction path diagrams estimated from thermodynamical data and from the dependence of the sticking probability on pressure, temperature, and coverage provide a suitable framework for a systematic characterization of the surface reactions observed.     

X射线荧光光谱法测定不锈钢中的组分

用X射线荧光光谱法测定了不锈钢中Si、Mn、P、Cu、Ti、W、Mo、V、Ni、Cr、Nb等11种元素的含量。对磨样条件、准确度和精密度进行了实验,实验表明本方法与化学法所测结果相符。     

电感耦合等离子体-质谱法测定纯铪或氧化铪中的25种杂质元素

建立了用电感耦合等离子体-质谱法(ICP-MS)测定纯铪或氧化铪中的Mg、Al、Si、P、Ca、Ti、V、Cr、Mn、Fe、Ni、Co、Cu、Zn、As、Zr、Nb、Mo、Cd、Sn、Sb、Ta、W、Pb和Bi等25种杂质元素含量的方法。铪金属室温条件下混酸溶解后可直接进样分析,氧化铪采用微波消解,辅助溶解后用ICP-MS测定。利用建立的方法,对铪及氧化铪中的杂质元素进行测定,加标回收率为86%—120%。各金属杂质含量均为10ng/mL的混合标准溶液平行7次进样的相对标准偏差均小于5%。方法操作简便、快速,检出限低,能够满足纯度为99.99%的铪金属或氧化铪中杂质分析的需要。     

Trace element composition of common sea buckthorn (Hippophae rhamnoides L.) tissues

Synchrotron radiation X-ray fluorescence analysis is used to determine for the first time the absolute content and biological accumulation coefficients for a set of 21 chemical elements (K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Zr, Nb, Y, Mo, and Pb) in the fruits, leaves, bark, roots, and root nodules of the sea buckthorn (Hippophae rhamnoides L. ssp. mongolica Rousi). It is found that all sea buckthorn tissues accumulate Ti, Nb, Cr, and Zr more intensively than the global average for terrestrial phytomass. On the other hand, none of the examined parts of the sea buckthorn plants accumulated the toxic elements Pb and As.     

γ-TiAl中Nb和Mo合金化效应的第一性原理研究

基于密度泛函理论框架下的第一性原理离散变分(DV)和DMol方法研究了4d过渡金属元素在γ-TiAl 中的择优占位行为及其Nb和Mo的合金化效应.转移能的计算结果表明Y，Zr，Nb，Mo在γ-TiAl中有Ti占位倾向，而Tc，Ru，Rh和Pb则表现为Al占位倾向.通过对差分电荷密度、Mulliken轨道集居数以及态密度的分析表明Nb和Mo可以提高杂质元素与其近邻基体元素之间的相互作用和相应原子之间的键合强度，导致较强的固溶强化效应. 关键词： 密度泛函理论 第一性原理 电子结构     

Vacuum arc ion charge-state distributions

Vacuum arc ion charge-state spectra have been measured for a wide range of metallic cathode materials. The charge-state distributions were measured using a time-of-flight diagnostic to monitor the energetic ion beam produced by a metal vapor vacuum arc ion source. Data were obtained for 48 metallic cathode elements: Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er Yb, Hf, Ta, W, Ir, Pt, Au Pb, Bi, Th, and U. The arc was operated in a pulsed mode with pulse length 0.25 ms: arc current was 100 A throughout. The measured distributions are cataloged and compared with earlier results. Some observations about the performance of the various elements as suitable vacuum arc cathode materials are also presented     

Thermal and structural characterization of Cu–Al–Mn–X (Ti,Ni) shape memory alloys

In this study, the Cu–Al–Mn–X (X = Ni, Ti) shape memory alloys at the range of 10–12 at.% of aluminum and 4–5 at.% manganese were produced by arc melting. We have investigated the effects of the alloying elements on the transformation temperatures, and the structural and the magnetic properties of the quaternary Cu–Al–Mn–X (X = Ni, Ti) shape memory alloys. The evolution of the transformation temperatures was studied by differential scanning calorimetry with different heating and cooling rates. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the aluminum and manganese content, and it was observed that the nickel addition into the Cu–Al–Mn system decreased the transformation temperature although Ti addition caused an increase in the transformation temperatures. The effect of the nickel and the titanium on the thermodynamic parameters such as enthalpy and entropy values was investigated. The structural changes of the samples were studied by X-ray diffraction measurements and by optical microscope observations at room temperature. It is evaluated that the element Ni has been completely soluble in the matrix, and the main phase of the Cu–Al–Mn–Ni sample is martensite, and due to the low solubility of the Ti, the Cu–Al–Mn–Ti sample has precipitates, and a martensite phase at room temperature. The magnetic properties of the Cu–Al–Mn, Cu–Al–Mn–Ni and Cu–Al–Mn–Ti samples were investigated, and the effect of the nickel and the titanium on the magnetic properties was studied.     

掺杂对Ni51.5Mn25Ga23.5相变行为和磁性的影响

通过往母合金Ni_51.5Mn₂₅Ga_23.5掺入7种IVA, VA和VIA 过渡族元素得到系列掺杂合金Ni_51.5Mn₂₃M₂Ga_{23 .5}.M为掺杂元素.实验结果表明，掺杂效应一般引起马氏体相变温度的下降，其中，W 的掺杂是7种元素中唯一使相变温度升高的特例，且出现了中间马氏体相变.同时，在价电子 浓度不变的情况下，相变更敏感于原子的尺度效应.实验发现，Ti，Zr，Hf，V四种非磁性元 素的掺杂使Mn原子磁矩减小，而Nb，Ta，W三种非磁性元素的掺杂却可以明显地增大Mn原子 的磁矩.在考察掺杂效应时，不能忽略马氏体相变引起的晶格变化对材料磁性的影响. 关键词： NiMnGa 掺杂 马氏体相变 磁性     

钍基熔盐堆用238群中子-48群光子耦合多群常数库的屏蔽基准验证

采用OKTAVIAN脉冲球实验对钍基熔盐堆用AMPX主库格式238群中子-48群光子耦合多群常数库进行了屏蔽基准验证,重点检验了该库中的F,Li,Be,C、Al,Si,Cr,Ni,Zr,Co,Cu,Mn,Mo,Nb,Ti,W,Pb同位素/元素的数据。采用SCALE 5.1程序系统中的XSDRN-PM程序进行一维屏蔽问题计算,将计算结果与实验测量数据及MCNP程序计算结果进行比较,发现中子泄漏谱的符合程度较好,而光子泄漏谱检验中发现大多数核素都出现了不同程度的高估。通过对GENDF格式到AMPX格式的转换程序MILER-4进行修正,解决了这一问题。通过对多群常数库的屏蔽基准验证,进一步证明了该库的可靠性。OKTAVIAN pulsed sphere experiment was used for Shielding Benchmarks of the AMPX formatted multi-group (238n-48γ) coupled neutron-gamma cross-section library for Thorium Molten Salt Reactor, of which the following isotopes/elements were checked-F, Li, Be, C, Al, Si, Cr, Ni, Zr, Co, Cu, Mn, Mo, Nb, Ti, W. One dimension shielding problem was calculated using XSDRN-PM program of SCALE 5.1 code system and results were compared with experiment results and MCNP calculated results, which shows that neutron leakage spectra agree well. Calculated results of photon leakage spectra of most facilities compared with MCNP results and experiment data are over-rated. MILER-4 code which is used for converting GENDF files produced by NJOY to the AMPX master library format is revised to solve this problem. The shielding benchmark verifications confirm the reliability of this new library.     

Microstructure and magnetic properties of NdFeB alloys by co-doping alnico elements

Elements of alnico 8 are added into Nd-Fe-B alloys fabricated by rapid solidification method. It is observed that the magnetic properties at high temperature improved by small addition of alnico elements. The Curie temperature of the alloys increased from 580 K for standard alloy to 639 K by 20% addition of alnico 8 elements. The spin reorientation temperature decreased from 133 K to 104 K. The TEM analysis showed that elements of alnico 8 refine the microstructure of Nd-Fe-B ribbons. The STEM analysis confirmed the heterogeneous distribution of Nd, Fe, Cu, Al, Ni and homogeneous distribution of Ti, Nb and Co. The boundaries of nano grains contain more than 70% ferromagnetic elements, ensuring strong inter-grain coupling among the grains.     

X射线荧光光谱法测定硅酸盐中硫等20个主、次、痕量元素

本文使用新研制的偏硼酸锂和四硼酸锂混合熔剂，在１０００℃熔融制样，以Ｘ射线荧光光谱法测定硅酸盐等样品中的Ｓ，Ｎａ，Ｍｇ，Ａｌ，Ｓｉ，Ｐ，Ｋ，Ｃａ，Ｔｉ，Ｍｎ，Ｆｅ，Ｂａ，Ｃｒ，Ｖ，Ｓｒ，Ｚｒ，Ｒｂ，Ｃｕ，Ｎｉ和Ｎｂ等２０种元素，采用理论α系数和康普顿散射线作内标校正元素间的吸收－增强效应。其分析结果的精密度和准确度可与化学法相比     

Atomic displacements in dilute alloys of Cr, Nb and Mo

Kanzaki lattice static method is used to calculate the atomic displacements due to substitutional impurities in 3d (Cr) and 4d (Nb, Mo) metals. Wills and Harrison interatomic potential is used to calculate dynamical matrix and the impurity-induced forces up to second nearest neighbors. The calculated atomic displacements for 3d, 4d and 5d impurities in Cr (V, Mn, Fe, Ni, Nb, Mo, Ta and W), Nb (V, Cr, Mn, Fe, Zr, Mo, Ta and W) and Mo (V, Cr, Mn, Fe, Zr, Nb, Ta and W) are tabulated up to 10 NN’s. The strain field due to 3d impurities is least in Cr metal while it is larger in Nb and Mo metals. For 4d and 5d impurities the strain is larger in Cr metal than in Nb and Mo hosts. Similar trend is found for relaxation energies also.     

Energetics and electronic structure of refractory elements in the dislocation of NiAl

Using DMol and the discrete variational method within the framework of the density functional theory,we study the alloying effects of Nb,Ti,and V in the [100](010) edge dislocation core of NiAl.We find that when Nb(Ti,V) is substituted for Al in the center-Al,the binding energy of the system reduces 3.00 eV(2.98 eV,2.66 eV).When Nb(Ti,V) is substituted for Ni in the center-Ni,the binding energy of the system reduces only 0.47 eV(0.16 eV,0.09 eV).This shows that Nb(Ti,V) exhibits a strong Al site preference,which agrees with the experimental and other theoretical results.The analyses of the charge distribution,the interatomic energy and the partial density of states show that some charge accumulations appear between the impurity atom and Ni atoms,and the strong bonding states are formed between impurity atom and neighbouring host atoms due mainly to the hybridization of 4d5s(3d4s) orbitals of impurity atoms and 3d4s4p orbitals of host Ni atoms.The impurity induces a strong pinning effect on the [100](010) edge dislocation motion in NiAl,which is related to the mechanical properties of the NiAl alloy.     

Elastic properties, thermal expansion coefficients and electronic structures of Ti0.75X0.25C carbides

Elastic properties, thermal expansion coefficients and electronic structures of Ti_0.75X_0.25C carbides (X=W, Mo, Ta, Nb, V, Hf, Zr, Cr and Al) were systematically investigated using ab initio density functional theory (DFT) calculations. The calculated elastic moduli, electronic structures and thermal expansion coefficients α(T) of pure TiC are in good agreement with experimental data and other DFT calculations. Based on a phenomenological formula, the trends of elastic properties and ductile/brittle behavior of Ti_0.75X_0.25C were analyzed. It was found that alloying elements W, Mo, Ta, Nb, V and Hf can increase elastic moduli, while Zr, Cr and Al reduce moduli. The nearly free electron model and Debye approximation were applied in the evaluation of α(T). The anharmonic effect was taken into account by including volume-dependent elastic moduli and Debye temperature. Results show that alloying additions of 3d V, 4d Zr and Mo slightly reduce α(T), while 3d Cr increases α(T), Al, 4d Nb, 5d Hf and W almost keep α(T) unchanged in Ti_0.75X_0.25C at high temperatures. The electronic structures of Ti_0.75X_0.25C were calculated and analyzed, and the electronic density of states was used to interpret variations of elastic properties and ductile/brittle behavior induced by alloying additions.     

掺杂元素对Mg2NiH4稳定性影响的第一性原理研究

本文采用基于密度泛函理论(DFT)的第一原理赝势平面波(PW-PP)方法,计算了低温相Mg2NiH4和(Mg2Ni,X)H4(X=Ag, Al, Ti或Zr)的生成热及电子结构,分析了掺杂元素对Mg2Ni氢化物稳定性的影响. 结果表明,掺杂导致了合金氢化物生成热的绝对值降低,合金氢化物的稳定性下降,且发现掺杂元素电负性越大,氢化物越不稳定. 从电子态密度图和Mulliken布居数分析知道,掺杂后合金氢化物释氢能力增强的主要原因在于Ni-H之间的成键减弱,以及掺杂元素诱导费米能级EF处电子数浓度N(EF)的增加.     

掺杂元素对Mg2NiH4稳定性影响的第一性原理研究

本文采用基于密度泛函理论(DFT)的第一原理赝势平面波(PW-PP)方法,计算了低温相Mg2NiH4和(Mg2Ni,X)H4(X=Ag, Al, Ti或Zr)的生成热及电子结构,分析了掺杂元素对Mg2Ni氢化物稳定性的影响. 结果表明,掺杂导致了合金氢化物生成热的绝对值降低,合金氢化物的稳定性下降,且发现掺杂元素电负性越大,氢化物越不稳定. 从电子态密度图和Mulliken布居数分析知道,掺杂后合金氢化物释氢能力增强的主要原因在于Ni-H之间的成键减弱,以及掺杂元素诱导费米能级EF处电子数浓度N(EF)的增加.