元素Tb对(Fe,Co)-B-Si-Nb块体非晶形成及磁性能的影响

用铜模吸铸工艺制备了[(Fe0.5Co0.5)0.72B0.192Si0.048 Nb0.04]100-xTbx和[(FeyCo1-y)0.72B0.192Si0.048Nb0.04]98Tb2块体非晶合金,并用XRD、DSC、振动样品磁强计(VSM)测试和分析了微量稀土元素Tb和不同Fe与Co比例对(Fe,Co)-B-Si-Nh体系玻璃形成能力、热稳定性及软磁性能的影响.试验表明,添加2 at%的Tb,提高了合金的非晶热稳定性和形成能力,制得的非晶合金棒的直径从φ2mm增加到φ3 mm,但饱和磁化强度下降;[(FeyCo1-y)0.72B0.192Si0.048Nb0.04]98Tb2合金随Fe与co比例从5:5增加至7:3时,合金的非晶形成能力呈下降趋势,但均能形成直径为φ2 mm的非晶棒,而其热稳定性和饱和磁化强度随铁含量的增大而提高.     

Co~(2+)取代Ni~(2+)对MgNiCuZn铁氧体纳米微粒磁学性能的影响

通过化学共沉淀法制备了纳米级的Mg0.05CoxNi0.35-xCu0.2Zn0.4Fe2O4铁氧体超细粉末,采用X射线衍射仪和振动样品磁强计分析研究了Co2+取代Ni2+对铁氧体结构和饱和磁化强度的影响。结果表明,试样的晶格参数a和平均粒径Dx随Co2+取代量的增加而增大;饱和磁化强度Ms随Co2+取代量的增加单调增大。     

镍含量对激光熔覆镍-铁基涂层结构与性能的影响

采用侧向同步送粉,激光熔覆+重熔的方式在低碳钢表面制备了两种Ni–Fe–Si–B–Nb合金涂层,化学成分分别为(Ni0.5Fe0.5)62Si18B18Nb2(原子数分数x/%)和(Ni0.6Fe0.4)62Si18B18Nb2(x/%)。探讨Ni含量变化对涂层物相组成、显微组织及其性能的影响。试验结果表明,当Ni和Fe的比为1:1时,涂层重熔层物相分析表现为非晶特征的漫散射峰,微观组织由等轴晶+非晶构成,而当Ni和Fe的比为3:2时,涂层重熔层物相分析无漫散射峰形成,微观组织为树枝晶。同时树枝晶组织的显微硬度值较低,这和涂层内部形成的奥氏体较多,而且无Fe2B相和非晶相生成有关。     

Ni/Co比例及微量Dy对FeCoNiBSiNb块体非晶合金玻璃形成能力和磁性能的影响

采用水冷铜模吸铸工艺制备了一系列的(Fe0.5Co1-xNix)72B19.2Si4.8Nb4(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.4)块体非晶合金.并采用X射线衍射仪(XRD)、差热分析仪(DTA)、振动样品磁强计(VSM)测试了块体非晶合金的结构、热稳定性和软磁性能.探讨了不同Ni/Co比例及添加稀土元素Dy对FeCoNiBSiNb系合金玻璃形成能力(GFA)、热稳定性及磁性能的影响.结果表明:当x=0.05,0.1,0.15,0.2时可制备出直径2mm的非品合金棒,但不能获得3mm非晶合金棒,x=0.25,0.3,0.4均不能获得直径2mm的非晶合金棒,且随Ni/Co比例的增大,即随Ni含量的增加,热稳定性先增加,后逐渐减小,过冷液相区△Tx逐渐减小,非晶合金的玻璃形成能力呈下降趋势,非晶合金的饱和磁化强度(Ms)下降.添加1 at%Dy后,提高了合金的非晶形成能力,可制备出直径3mm的[(Fe0.5Co0.4Ni0.1)72B19.2Si4.8Nb4]99Dy1非晶合金棒,但合金的Ms下降.     

Fe72.7Cu1Nb2V1.8Si13.5B9合金的热磁分析

研究了Fe(72.7)Cu1Nb2V(1.8)Si(13.5)B9非晶合金在不同温度（763—883K）退火1h后的热磁曲线（σs－T曲线）借助于碰分析的方法，由σs1/B－T曲线并通过X射线衍射分析确定了合金中α－Fe（Si）相和剩余非晶相的体积分数、饱和磁化强度及Curie温度随退火温度Ta的变化及其相互关系.结果表明，当Ta＜823K时α－Fe（Si）相的饱和磁化强度σsα和Curie温度随Ta的增加略有下降，当Ta≥823K时σsα和TCα保持不变；剩余非晶相的饱和磁化强σsA度和Curie温度在整个退火温度范围内均随Ta的增加而单调下降并且两者之间呈近似直线关系。     

热处理参数对Fe基非晶软磁合金带磁性和磁化强度分布影响

俄罗斯乌拉尔联合大学Н. А. Ску лкцна等人研究了大气中热处理保温时间和冷却速度对饱和磁致伸缩Fe基非晶软磁合金带磁性和磁化强度分布影响。研究结果表明，最高磁导率同热处理保温时间依从性与相应合金带饱和磁化强度有关，与大气中热处理时一定的保温时间所发生的过程有关，快的冷却速度对磁性高低影响不单一。如果大气中热处理后表面基本上为非晶态或在表面形成接近最佳厚度的非晶一晶化层，那么这种快冷速度就有利于磁性提高。     

新型Y-Fe-Co-B大块非晶合金的制备与磁性能研究

用水冷铜模吸铸方法制备了最大截面直径为2mm的Y6Fe60.5Co11.5B22铁基大块非晶合金，研究了冷却速率对合金磁性能的影响，分析并计算了合金的临界冷却速率。大块Y6Fe6.5Co11.5B22非晶合金具有良好的软磁性能：其矫顽力Hc=2．53A／m，饱和磁化强度Ms=1．24T，初始磁化率明显高于相同成分的晶态合金。热稳定性分析表明，该合金具有较高的非晶形成能力，其形成非晶的临界冷却速率（Rc）约为119K／s。     

磁脉冲对铁基非晶合金晶化组织和磁性能的影响

采用XRD和VSM等方法研究了经过磁脉冲处理以及晶化退火处理后的Fe64Ni1Al4.5Cu0.5Ga2P9.65B9.6Si3C5.75非晶合金的组织和磁性能的变化。XRD结果表明,经过磁脉冲处理+晶化退火处理后合金的析出相种类和晶化体积分数增加,晶粒尺寸减小,晶粒细化。VSM结果表明,合金饱和磁化强度Ms有所提高,剩余磁化强度Mr、剩磁比Mr/Ms、矫顽力Hc有所降低,合金软磁性能得到改善。     

块体非晶合金Fe-Ni-P-B-Ga的制备与性能

采用助熔剂净化和铜模铸造相结合的工艺，用工业纯原料制备出块体(Fe40Ni40P14B6)100-xGax(x=0-8)合金，样品为直径3mm的圆柱体或宽6mm、厚1mm的片材，长度都在10至15mm左右，XRD与DSC分析表明，x=4—6时易于形成非晶合金，测试表明，这些非晶合金具有优异的耐腐蚀性能和软磁性能，显微硬度测试表明，对相同成分合金，非晶态的显微硬度值比晶态的低，适量Ga的加入，提高了Fe—Ni—P—B合金的非晶形成能力。     

Co_(0.5)Ni_(0.5)Fe_2O_4纳米纤维的静电纺丝法制备、表征及其磁性能

采用溶胶-凝胶法结合静电纺丝技术成功制备直径为150~400 nm的Co0.5Ni0.5Fe2O4铁氧体纳米纤维,并利用TG-DTA、XRD、FTIR、FESEM、TEM和VSM对样品进行表征。结果表明:前驱体纤维经450℃焙烧后可基本形成纯相晶态的目标产物Co0.5Ni0.5Fe2O4纳米纤维;随着焙烧温度的升高,纤维直径逐渐减小,晶粒尺寸逐渐增大,纤维表面粗糙度加强,其微观形貌由多孔结构向项链状结构转变;所制得的Co0.5Ni0.5Fe2O4纳米纤维的饱和磁化强度由450℃时的35.8 A.m2/kg单调增加到1 000℃时的80.2 A.m2/kg,而矫顽力呈现先增大后减小的趋势,在550℃附近时达到最大值,意味着其单畴临界尺寸约为30 nm,且发现在单畴尺寸范围内,矫顽力与平均晶粒尺寸的0.7次方成正比,与随机各向异性模型所预测的结果基本吻合。此外,低温(77 K)磁测量显示,与室温相比,样品的矫顽力和剩余磁化强度均大幅提高,但饱和磁化强度明显下降。     

预氧化及预氧化—还原处理改善NdFeB微晶磁粉的抗氧化性能

以重铬酸钾为氧化剂及亚硫酸氢钠为还原剂，分别在强氧化条件下及氧化－还原条件下处理快淬ＮｄＦｅＢ微晶磁粉表面，研究了处理后磁粉的热氧化以及抗氧化机理，结果表明，预氧化及预氧化－还原处理能使磁粉的抗氧化性能明显提高。     

Properties and structure of ultrafine amorphous Fe-Ni-B powder obtained by borohydride reduction

Ultrafine amorphous Fe-Ni-B powders were prepared by borohydride reduction, and their properties and structure were investigated by extended x-ray absorption fine structure (EXAFS), x-ray photoelectron spectroscopy (XPS), small-angle x-ray scattering (SAXS), Mössbauer spectra, transmission electron microscopy (TEM), differential scanning calorimetry (DSC), etc. The SAXS results for Fe₄₈Ni₂₁B₃₁ powders reveal the particle size statistic distribution, which is 1.7 nm, 80 % ; 6.4 nm, 8 % ; and 15.3 nm, 12 %. TEM micrographs demonstrate the aggregates with fractal dimension of 1.5. The short-range order parameters of Fe₄₈Ni₂₁B₃₁ powders are obtained from EXAFS measurement. The XPS studies reveal that the higher H_c values of the powder prepared at higher reaction temperature relate to the appearance of the satellite structure at about 715.6 eV, which is characteristic for iron oxides, FeO/Fe_xO. This new interesting finding has been explained by the lattice misfit on the interface between the matrix and oxides, based on EXAFS studies. The crystalline behavior and magnetic properties demonstrate that there is no significant difference in amorphous structure between the chemically synthesized powders and meltspun ribbons. However, the reasonable prediction of difference of amorphous structure and its formation mechanism between them has been proved by the XPS depth profile of Fe₄₈Ni₂₁B₃₁ powders, exhibiting considerable surface enrichment of boron and nickel, and EXAFS studies, showing a stronger interaction between nearer neighbors in the powders.     

Selective laser sintering/melting (SLS/SLM) of pure Al,Al–Mg,and Al–Si powders: Effect of processing conditions and powder properties

Selective laser sintering/melting (SLS/SLM) processing difficulties of aluminium powders had been attributed to issues associated with laser–materials interaction only while neglecting the role of powder properties. This study provides a wholistic understanding of factors that influence the development of SLS/SLM processing window, densification, and microstructure of pure Al, Al–Mg, and Al–Si powders, fabricated in single and multiple layer parts by exploring the roles of processing and material parameters. It was demonstrated that similarities existing in the SLS/SLM processing maps of the powders could be attributed to similarities in their packing densities with the alloying addition of magnesium and silicon having no predominant effect on their processing maps’ boundaries. Rather, alloying addition has significant effect on the nature of the evolved surface morphology of SLS/SLM processed aluminium powders in their processing windows. In addition, the flow and solidification behaviour of the melt pool of the powders during single layer scan was strongly influenced by the particle morphology and oxygen content of the powders as well as applied energy density. The energy density in the range of 12–16 J/mm² was found to be the threshold below which SLS was predominant and above which SLM occurred for the investigated powders. Moreover, successful oxide disruption phenomena which is necessary for inter-particulate coalescence in multi-layered SLS/SLM processed aluminium powders are found to be mainly controlled by the amount of oxide in the as-received powder, the degree of the uniformity of the distribution of the surface oxide film covering the aluminium particles, the nature of thermal mismatch existing between the oxide film and the parent aluminium particle which was dependent on the phase present in the oxide film. Al–12 wt% Si powder is hereby affirmed as a suitable candidate material for SLS/SLM process due to its low thermal expansion and uniform distribution of its surface oxide films as well as the mullite phase in its oxide film.     

Fe-Ni-B超细非晶粉的XPS研究

用X射线光电子能谱（XPS）研究了用化学还原法制备的FeNiB超细非晶粉.表征了粉末颗粒表面层各元素状态和分布的特性.     

微波法制备LaF3超细粉

以La2O3、HCl为原料制备了LaCl3,并直接用双柱法,以LaCl3溶液同NH4HCO3溶液作用合成了粒度较小的La2(CO3)3粉体;以粉体La2(CO3)3为镧源与NH4F混合,在微波作用下经过固相化学反应,合成了LaF3超细粉;研究了不同分散剂等反应条件对合成LaF3超细粉的粒度和纯度的影响;通过X射线衍射(XRD)检测了不同途径合成的LaF3超细粉体的纯度,通过扫描电镜(SEM)、透射电镜(TEM)测试了不同途径合成的LaF3超细粉体颗粒的粒度和形貌.结果表明:用乙醇作为分散剂经微波加热固相合成得到了纯度较高,平均粒度约为50 nm的LaF3超细粉.     

碳化镧锰水解氧化法制备La0.978Mn0.946O3氧化物

碳化镧锰合金在室温常压下进行水解氧化反应,洗涤并在50～80℃烘干得到La(OH)3和Mn3O4纳米粉。探讨了反应温度、反应时间、悬浮液浓度和碳化镧锰颗粒大小对晶粒尺寸的影响。优化工艺条件为:反应温度35℃,反应时间18 h,悬浮液浓度0.1 g/ml,碳化镧锰颗粒小于0.15 mm,得到比表面积为122.6 m2/g的La(OH)3和Mn3O4纳米粉。将该纳米粉分别在400、600、800℃和1 000℃煅烧2 h,最终得到晶化程度较好的La0.978Mn0.946O3氧化物。     

超细碳化钨粉末特性对金刚石锯片刀头显微结构的影响

采用超细WC粉末和工业级的Sn、Ni、Co、Cu粉末以及金刚石为原料，经真空烧结后制备成金刚石锯片刀头。用扫描电镜（SEM）观察了WC粉末和合金的形貌，用能量散射谱（EDS）测试了合金的微区成分分布。研究结果表明，超细WC粉末的添加能改善Sn-Ni-Co-Cu结合金刚石锯片刀头的显微结构，超细WC含量的增加有利于材料晶粒的细化和强度提高，Cu是烧结中产生液相和使成分偏析的重要影响因素，Co对晶粒异常生长影响很大，Sn的添加有利于晶粒的细化。     

Wear and thermal properties of Zr-based amorphous surface alloyed materials fabricated by high-energy electron beam irradiation

Zr-based amorphous surface alloyed materials were fabricated by high-energy electron beam irradiation in this study. A mixture of Zr-based amorphous powders and LiF + MgF₂ flux was deposited on a pure copper substrate, and then an electron beam was directed on this powder mixture to fabricate a one-layered surface alloyed material. A two-layered surface alloyed material was also fabricated by irradiating electron beam again onto the powder mixture deposited on the one-layered surface alloyed material. The microstructural analysis results indicated that a number of coarse crystalline phase particles were formed in the one-layered surface alloyed layer, whereas a small amount of fine and hard crystalline particles were homogeneously distributed in the amorphous matrix of the two-layered surface alloyed layer. Owing to these fine and hard crystalline particles, the hardness and wear resistance of the two-layered surface alloyed layer improved over the one-layered surface alloyed layer or other kinds of surface alloyed layers. The thermal conductivity of the two-layered surface alloyed layer was much lower than that of titanium-alloy-based or stainless-steel-based surface alloyed layers. These findings suggested the possibility of applying Zr-based amorphous surface alloyed materials to high wear-resistant thermal barrier coatings or parts.     

Microstructural, thermal and magnetic properties of amorphous/nanocrystalline FeCrMnN alloys prepared by mechanical alloying and subsequent heat treatment

Amorphous FeCrMnN alloys were synthesized by mechanical alloying (MA) of the elemental powder mixtures under a nitrogen gas atmosphere. The phase identification and structural properties, morphological evolution, thermal behavior and magnetic properties of the mechanically alloyed powders were evaluated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM), respectively. According to the results, at the low milling times the structure consists of the nanocrystalline ferrite and austenite phases. By progression of the MA process, the quantity and homogeneity of the amorphous phase increase. At sufficiently high milling times (>120 h), the XRD pattern becomes halo, indicating complete amorphization. The results also show that the amorphous powders exhibit a wide supercooled liquid region. The crystallization of the amorphous phase occurs during the heating cycle in the DSC equipment and the amorphous phase is transformed into the crystalline compounds containing ferrite, CrN and Cr₂N. The magnetic studies reveal that the magnetic coercivity increases and then decreases. Also, the saturation magnetization decreases with the milling time and after the completion of the amorphization process (>120 h), the material shows a paramagnetic behavior. Although the magnetic behavior does not considerably change by heating the amorphous powders up to the crystallization temperature via DSC equipment, the material depicts a considerable saturation magnetization after the transformation of the amorphous phase to the nanocrystalline compounds.     

Oxidation process of lanthanum hexaboride ceramics

Oxidation process of lanthanum hexaboride (LAB6) ceramic powder was investigated. The LaB6 powder sampies were heated continually fTom room temperature to 1 473 K at a heating rate of 10 K/min by differential scanning calorimetry. The oxidation tests were conducted at different exposure temperatures. The phases and morphologies of the samples before and after exposure were analyzed by XRD and SEM. It was pointed out that before 1 273 K, LaB6 has high oxidation resistant ability, which was due to that the oxide layer hinders the oxygen diffusion fTom outer to the surface of LaB6 grains. The oxide layer was composed of the transition phases, which were composed of La203 and B2O3 formed fi‘om the initial oxidation; when the oxidation temperature exceeded 1 273 K, protective layer was destroyed due to the vaporization of liquid B2O3. Based on the results of X-ray diffraction analysis, oxidation process of LaB6 ceramicpowder can be described as follows: Before 1 273 K, lanthanum borate, La(BO2)3 was formed on the surface of samples,then lanthanum oxide (La2O3) and boron oxide (B2O3) were present on the surface of samples oxidized when the tempera-ture reached to 1 473 K.