Nd3（Fe,Mo）29化合物及其氮化物的磁结构和内禀磁性

制备了具有Nd3（Fe,Ti）29型单斜结构的单相铁基金属间化合物Nd3（Fe,Mo）29及其氮化物,详细研究了：其在4．2K～300K之间的磁结构;磁晶各向异性;居里温度Tc,饱和磁化强度σs等内禀磁性。研究结果表明：Nd3（Fe,Mo）29金属间化合物氮化后仍保持母相结构,氮化后的晶胞体积,居里温度Tc和饱和磁化强度σs分别比氮化前提高了5．9％,70．9％,6．6％;N3d（Fe,Mo）29金属间化合物在230K左右存在自族重取向,温度低于230K时,其磁晶各向异性为锥面,温度高于230K时,其磁晶各向异性为易面;氮化后自族重取向消失。     

Y3（Fe,Mo）29金属间化合物的结构特性

使用Ｒｉｅｔｖｅｌｄ方法对Ｙ３（Ｆｅ,Ｍｏ）２９金属间化合物的Ｘ射线衍射谱和中子衍射谱进行分析,得出了Ｙ３（Ｆｅ,Ｍｏ）２９金属间化合物Ａ２／ｍ空间群的结论。坐标变换结果表明：Ｙ３（Ｆｅ,Ｍｏ）２９金属间化合物的空间结构是１：１２和２：１７的混合特性。     

金属间化物Nd(Fe_(1-x)Co_x)_(10)V_2的磁性能机制

通过X射线衍射.磁测量和M(?)ssbauer谱测定了Nd（Fe1-Cox）10V2的结构和磁性.结果表明,Nd（Fe1-xCox）10V2（x=0,0.05,0.10,0.15,0.20）化合物的晶体结构均为ThMn12型结构;随着 Co含量x的增大,晶格常数将单调减少.Co原子的替代将导致化合物各个Fe晶位上的磁超精细场值Bhf逐渐增加.Co部分取代Nd（Fe1-xCox）10V2中的Fe原子时.将择优占据8i铁晶位.取向样品NdFe10V2的热磁曲线和变温M(?)ssbauer谱研究结果表明.该化合物在T=120K条件下存在自旋重取向现象.     

高强度Fe-(P,C)基块体金属玻璃的形成(英文)

采用铜模吸铸法制备不同直径的Fe71Mo5-xNbxP12C10B2(x=1～5)合金棒。利用X射线衍射、差热分析和压缩测试等手段分别研究Nb替换Mo对Fe71Mo5P12C10B2合金的结构、热稳定性及室温力学性能的作用。结果表明:随着Nb含量的增加,合金的玻璃形成能力有所降低,而断裂强度逐步增加;Fe71Mo2Nb3P12C10B2金属玻璃的断裂强度高达4.0GPa,且具有1%的室温压缩塑性。Fe-P-C基块体金属玻璃断裂的强度提高的原因主要是由于Nb替换Mo有利于形成似网格状结构且增强原子间结合力。     

Fe和Mo元素对TiAl金属间化合物显微组织和性能的影响(英文)

β相可以提高TiAl金属间化合物的塑性。通过显微组织分析和变形行为的评估研究β稳定性元素Fe和Mo对Ti-45Al-xFe-yMo(x,y=1,2,3,4)合金的影响。结果表明:合金中的B2(β)相随着Fe和Mo元素含量的增加而增多,Mo表现出强的β稳定性。加入3%Fe和2%Mo后,合金的晶粒得到细化,其尺寸达到12-m。由于具有一定量的β相,细化后的Ti-45Al-3Fe-2Mo合金在790℃具有良好的塑性。     

添MgO-Y_2O_3的Fe-Mo包覆Si_3N_4复合粉末反应烧结中组织形成与演化分析

在非均相沉淀法制备的Fe-Mo包覆Si3N4金属陶瓷粉末中添加助剂MgO-Y2O3进行常压烧结,采用X线衍射仪(XRD)、电子能谱(EDS)、电镜扫描(SEM)等方法研究了不同烧结温度下该金属陶瓷相组成和显微结构等方面的演化趋势。结果表明:温度升高有利于金属相的转变和液相的生成,在复合粉末还原过程中,Si3N4的强还原性将Mo、Fe依次直接还原出来并反应生成Fe3Mo化合物,随着还原温度的升高,该金属间化合物与Si3N4反应生成Fe3Mo3N;同时Mg、Y氧化物与基体反应生成的MgSiO3、Fe17Y2加速了Fe3Mo3N的形成。1 600℃烧结时,Fe3Mo3N仍能稳定存在,但在1 700℃烧结时发生分解,材料组织中出现大量长径比较高的晶须状物质生成,同时表面粘附一层小颗粒物质.烧结温度为1 750℃时,金属小颗粒相仍得以保留,材料基体中晶须状物质消失。     

机械合金化制备纳米晶Al65Fe25Ni10合金粉

采用X射线衍射（XRD），扫描电子显微镜（SEM）和差热分析仪（DTA）等研究了Al65Fe25Ni10元素混合粉末在机械合金化过程中的结构演变及热稳定性。结果表明：球磨5h后的粉末样品退火处理后生成Al5Fe2和Al3Ni2金属间化合物。球磨500h后得到纳米尺寸的Al（Fe，Ni）无序相。     

MA-PAS和MA-HP烧结制备的Fe_3Al金属间化合物的组织和力学性能

以机械合金化Fe-28%Al（摩尔分数）合金粉末为原料,分别采用等离子活化烧结（PAS）和热压烧结（HP）方法制备致密度高达99%的Fe3Al金属间化合物。XRD和TEM测试结果表明：PAS烧结试样保留了机械合金化粉末的A2无序结构,并呈现出亚微米晶粒区域（〉1μm）和纳米晶粒区域（〈500nm）双峰分布的特征,而HP烧结试样为部分D03有序结构,晶粒尺寸在1～2μm的范围内。压缩试验表明：在室温至800℃的条件下,采用两种方法烧结的Fe3Al金属间化合物具有近似的压缩强度,虽然当温度超过400℃后压缩屈服强度均急剧下降,但在800℃时其压缩屈服强度仍高达100MPa,远高于铸造态Fe3Al金属间化合物。相比于HP烧结和铸造态Fe3Al金属间化合物,PAS烧结Fe3Al金属间化合物表现出优异的室温塑性,其室温压缩工程应变为20%。组织结构分析和力学性能测试结果表明,超细晶无序组织有利于Fe3Al金属间化合物室温塑性和高温强度的同时增强。     

Y(Mn_(1-x)Fe_x)_(12)的结构和磁性

稀土金属R和3d过渡族金属M形成一系列金属间化合物,如RM_5,RM_2,R_2M_(17)等已作为新型磁性材料应用,而RM_(12)型化合物,可能由于除Mn以外,像Fe,Co,Ni等都不能建立RM_(12)相,并且RM_(12)是反铁磁的,以前研究较少。我们用Fe代Mn,研究三元金属间化合物R(Mn,Fe)_(12)单相存在的条件以及通过原子代换的方法,改变合金的电子组态和磁性离子间的相互作用,从而影响和改变物体的磁性。     

Mo中间层对防止Al_2O_3/Kovar钎焊接头裂纹的作用(英文)

为避免Al2O3陶瓷／Kovar接头裂纹的产生,在Kovar表面磁控溅射金属Mo,并使用Ti-Cu-Ni活性钎料进行钎焊试验。通过扫描电镜和能谱对界面微观组织和成分进行了分析。结果表明,当溅射钼中间层的厚度为14．2μm时,在Al2O3／Kovar界面处,Mo中间层可阻碍Kovar中Fe元素与钎料中Ti元素相互反应产生脆性FexTiy金属间化合物,防止了界面处裂纹的生成。     

Peculiarities of the R3(Fe,Si)29 phase formation in the Sm---Fe---Si system

The phase content of the Sm(Fe_1−xSi_x)_y alloys (0.05≤x≤0.15; 8.5≤y≤12) has been studied by X-ray diffraction using micromonocrystals. The compounds Sm₂(Fe,Si)₁₇, Sm(Fe,Si)₁₂ and a novel Sm₃(Fe,Si)₂₉ compound with a monoclinic unit cell are found. The lattice parameters of Sm₃(Fe,Si)₂₉ are: a=1.056 nm, b=0.850 nm, c=0.966 nm, β=96.8°. This compound forms as a result of a solid state transformation from the high-temperature Sm₂(Fe,Si)₁₇ phase. Diffuse effects observed in rocking photographs suggest transition structures arising from this transformation. The Curie temperatures of Sm₃(Fe,Si)₂₉ vary in the interval 496–521 K.     

用CBED测定PrCo_(12)B_6化合物的空间群

用会聚束电子衍射(CBED)方法测定了PrCo_(12)B_6化合物的空间群为R3m.     

DETERMINATION OF SPACE GROUP OF PrCo_(12)B_6 COMPOUND BY CONVERGENT BEAM ELECTRON DIFFRACTION

The space group of PrCo_(12)B_6,compound has been determined using the convergent beam elec-tron diffraction method.The space group is found to be R3m.     

Spontaneous volume magnetostriction of Dy2AlFe12Mn4 compound

The structure and magnetic properties of Dy2AlFe12Mn4 compound have been investigated by means of X-ray diffraction and magnetization measurements. The Dy2AlFe12Mn4 compound has a hexagonal Th2Ni17-type structure. Negative thermal expansion was found in Dy2AlFe12Mn4 compound from 229 to 280 K by X-ray dilatometry. The coefficient of the average thermal expansion is α= -3.8×10-5 K-1. The magnetostrictive deformations from 105 to 270 K have been calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs; decreases from 6.2×10-3 to near zero with the temperature increasing from 105 to 270 K, the spontaneous linear magnetostrictive deformation λc. along the c axis is much larger than the spontaneous linear magnetostrictive deformation λa in basal-plane at the same temperature except close to 249 K.     

Ce(Au,Sb)2 with UHg2 structure type, a new member of the AlB2 family

A new ternary compound Ce(Au,Sb)₂, with a homogeneity range has been observed from X-ray powder diffraction of as cast alloys, a = 4.743–4.712 Å, c = 3.567–3.768 Å. Its crystal structure was investigated by X-ray diffraction from Ce(Au_1−xSb_x)₂ (x = 0.266) single crystal: CAD-4 automatic diffractometer, Mo K radiation, a = 4.7256(6) Å, c = 3.6711(6) Å, P6/mmm space group, V = 70.997(17) Å³, Z = 1, ρ = 10.732 Mg/m³, μ = 76.369 mm⁻¹, R₁ = 0.0415, wR₂ = 0.0793 for 99 reflections with I > 2σ(I₀). The coordination polyhedron of X (X = 0.734Au + 0.266Sb) atom is a full-capped trigonal prism [XCe₆X₃X₂]. Ce atom is coordinated by 14 atoms: [CeX₁₂Ce₂]. The compound is isotypic with UHg₂ structure, a deformation derivative of AlB₂ structure type. It forms isostructural compounds with La and Pr.     

Phase diagram of the CsBr-CaBr2 system

The phase diagram of the CsBr-CaBr2 system was re-determined by using differential thermal analysis and high ternperature and room ternperature X-ray diffraction analysis. It is concluded that there are three intermediate compounds in this system： a.congruently melting compound, CsCaBr3, with a melting point of 823℃ and two incongruently melting compounds, Cs2CaBr4 and Cs3Ca2Br7, whose peritectic points being 597℃ and 635℃, respectively. X-ray diffraction analysis indicated that compound CsCaBr3 is of slightly distorted perovskite structure.     

Crystal structure of La5Ti4GaO17

The crystal structure of La₅Ti₄GaO₁₇ compound synthesized by heat-treatment of the co-precipitated hydroxy-oxalates has been determined by the X-ray powder diffraction. It was found that crystal structure of La₅Ti₄GaO₁₇ belongs to the CaLa₄Ti₅O₁₇-type structure (space group Pmnn, a = 0.3912(1) nm, b = 3.128(1) nm, c = 0.5523(1) nm, Z = 2). The final R_W value is equal to 0.081 for 169 independent reflections.     

The 473 K isothermal section of the Cu–Ti–Sn ternary system

The phase relationships of the Cu–Ti–Sn ternary system at 473 K have been investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), optical microscopy (OM) and differential thermal analysis (DTA). The isothermal section consists of 17 single-phase regions, 33 two-phase regions and 17 three-phase regions. The existence of 12 binary compounds and 2 ternary compounds, namely Cu₄Ti, Cu₃Ti₂, Cu₄Ti₃, CuTi, CuTi₂, Cu₃Sn, Cu₆Sn₅, Ti₃Sn, Ti₂Sn, Ti₅Sn₃, Ti₆Sn₅, Ti₂Sn₃, CuTi₅Sn₃ and CuTiSn, are confirmed in the Cu–Ti–Sn ternary system at 473 K. No new ternary compound is found. The maximum solid solubility of Cu in Ti₆Sn₅ was approximately 10 at.% Cu.