不同气氛下机械合金化制备的纳米晶Fe60Cr40粉末的磁性能

Magnetic properties of nanocrystalline Fe60Cr40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and 57 Fe Mossbauer spectrum. The results show that the Fe60 Cr40powders keep the bcc structure during milling in air and vacuum. The saturation magnetization of the Fe60 Cr40 powders milled in vacuum and air decreases with the increase of the milling time up to 45 h. The decrease of saturation magnetization of the Fe60 Cr40 powders milled in vacuum is due to the formation of Fe-Cr solid solution, while in air it is due to the formation of paramagnetic disorder structure and solid solution.     

γ''-(Fe1-xNix)4N粉末的制备及其结构与磁性研究

用化学共沉淀法和在NH3/H2气氛下氮化处理得到了一系列不同Ni含量的Fe-Ni-N多晶粉末.分别用X射线衍射(X-ray Diffraction XRD)和振动样品磁强计(Vibrating Sample Magnetometer VSM)做了结构和磁性的测量.结果表明:制备单相γ'-(Fe1-xNix)4N粉末与NH3/H2气流比、热处理温度以及时间有关.随着Ni含量的增加,材料的晶格常数逐渐减小;饱和磁化强度(Ms)随着Ni含量的增加而下降,矫顽力(Hc)的变化比较复杂.Ni含量在0.20～0.26之间较容易得到单相的γ'-(Fe1-xNix)4N粉末,并且有较高的磁性.计算了Fe0.99Ni0.01N多晶粉末的饱和磁化强度,结果与实验值很接近.     

γ′（Fe1-xNix）4N粉末的制备及其结构与磁性研究

用化学共沉淀法和在NH3／H2气氛下氮化处理得到了一系列不同Ni含量的Fe-Ni-N多晶粉末。分别用X射线衍射（X-ray DiffractionXRD）和振动样品磁强计（VibratingSampleMagnetometerVSM）做了结构和磁性的测量。结果表明：制备单相γ′（Fe1-xNix）4N粉末与NH3／H2气流比、热处理温度以及时间有关。随着Ni含量的增加，材料的晶格常数逐渐减小；饱和磁化强度（Ms）随着Ni含量的增加而下降，矫顽力（Hc）的变化比较复杂。Ni含量在0．20～0．26之间较容易得到单相的γ′（Fe1-xNix）4N粉末，并且有较高的磁性。计算了Fe0.99Ni0.91N多晶粉末的饱和磁化强度，结果与实验值很接近。     

在室温和常压下用机械合金化方法制备Fe5C2金属间化合物

Single phase Fe5C2 intermetallic compound was prepared by mechanical alloying method. The phase and crystal structure of sample were analyzed with X-ray differaction spectrum. The decomposing temperature of the Fe5C2 compound is 596.4℃ determined by the DSC curve. It is further shown that the size of nanometer crystal grain is an important condition for carrying out the solid state reaction at room temperature and normal pressure.     

Fe73.5Ag1Nb3Si13.5B9合金的结构和磁性

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｉｎ 1988,Ｙｏｓｈｉｚａｗａａｎｄｃｏ ｗｏｒｋｅｒｓ[1] ｒｅｐｏｒｔｅｄｆｏｒｔｈｅｆｉｒｓｔｔｉｍｅｏｎａｎｅｗｇｏｏｄｓｏｆｔｍａｇｎｅｔｉｃａｌｌｏｙｃａｌｌｅｄＦｉｎｅｍｅｔ.Ｉｔｃｏｎｓｉｓｔｅｄｏｆｕｌｔｒａｆｉｎｅｇｒａｉｎｓｔｒｕｃｔｕｒｅｐｒｅ ｐａｒｅｄｂｙｔｈｅｃｒｙｓｔａｌｌｉｚａｔｉｏｎｏｆＦｅ Ｓｉ ＢａｍｏｒｐｈｏｕｓａｌｌｏｙｗｉｔｈａｄｄｉｔｉｏｎｓｏｆＣｕａｎｄＮｂ[1～ 3] .Ｔｈｅｆｏｒｍａｔｉｏｎｏｆｔｈｉｓｐａｒｔｉｃｕｌａｒｓｔ…     

Structure and Magnetic Properties of Fe1-xCx Solid Solution Prepared by Mechanical Alloying

Supersaturated solid solutions Fe1-xCx （0≤x≤0.9 ） of wide composition range have been prepared by mechanical alloying process. Nanocrystalline phase was formed for 0 ≤ x ≤ 0.67 and a large grain phase for 0.75 ≤ x ≤ 0.9. The large fraction of graphite volume puts off formation of nanocrystalline phase for high carbon content. In the large grain phase, magnetization follows simple magnetic dilution, and eoereivity He is mainly due to dissolution of carbon at grain boundaries. In the nanocrystalline phase the alloying effect of carbon is revealed by a distinct reduction of average magnetic moment. The increasing lattice constant with increasing carbon content is observed for x ≤ 0.5, suggesting that the high carbon concentration may enhance diffusion of carbon into the Fe lattice. It shows a discontinuity in the Hc variation with a grain size D of nanocrystalline phase. For small grain D below the critical value, Hc increases with D. For a large grain D, Hc decreases with increasing D. The solubility limit of carbon in a-Fe extended by nanocry- stalline phase formation is discussed.     

稀土永磁R2Fe14B的结构和磁性分析

本文介绍了稀土铁金属间化合物R2Fe14B及其掺杂系列的制备方法和晶体结构；分析和讨论了它们的内禀磁性；同时也反映了目前国际上永磁材料的研究进展和方向。     

Fe掺杂In_2O_3薄膜的结构及磁性研究

在室温条件下采用直流磁控溅射方法并结合原位空气退火工艺,在普通玻璃基片上,制备了不同Fe掺杂量的In_2O_3薄膜。实验结果表明,退火氛围及Fe的掺杂量对In_2O_3薄膜的微结构、形貌及磁特性都有着很大的影响。空气中773K下退火30min的In_2O_3薄膜样品则结晶状态良好,不同Fe掺杂的In_2O_3薄膜样品均表现出室温铁磁性。     

微乳液法制备纳米Fe3O4磁性颗粒的研究

在没有惰性气体保护下，以工业煤油作油相、AEO3＋TX10作表面活性剂、正丁醇作助表面活性剂，分别配成含FeSO4、Fe（NO3）3和NaOH的两种微乳液，采用双乳液混合法制备纳米磁性Fe2O4微粉，并研究了不同的工艺条件对产物物相组成和粒径的影响，得出了最佳实验工艺条件。最后，对所制备产物的性能进行了分析和测试，结果表明：产物的饱和磁化强度较大，矫顽力较小（几乎为零），呈现超顺磁性．是较好的软磁材料。     

磁性纳米Fe3O4的制备及性能表征

本文介绍纳米Fe3O4微粒和以纳米Fe3O4为核磁体的靶向药物的制备，对它们的性质进行XRD、IR、TEM、SEM、EDS表征，并对纳米Fe3O4微粒和以Fe3O4为载体的靶向药物进行了扩大化实验。     

球磨制备Mg-In-Zn三元固溶体的储氢性能及机理

采用“烧结-球磨”方法制备Mg0．92 In0．05 Zn0．03三元固溶体合金,减小了Mg的晶格常数.利用粉末X-射线衍射分析合金的相组成、微观结构和吸放氢过程的相转变,通过扫描电镜观察合金的微观形貌及相分布.采用体积法测定合金的等温吸放氢曲线（ PCT）和动力学曲线,确定了合金的吸放氢反应焓变、熵变及氢化反应激活能.结果表明： Mg0．92 In0．05 Zn0．03三元固溶体具有良好的活化性能和动力学性能,脱氢反应焓降低至-68．6 kJ/mol H2.     

Dependence of Nanocrystalline Phase Formation and Magnetic Properties in Fe 25 Ni 75 on Ball Milling Time

ａｎｄ Ｍａｇｎｅｔｉｃ Ｐｒｏｐｅｒｔｉｅｓ ｉｎ Ｆｅ＿（２５）Ｎｉ＿（７５） ｏｎ Ｂａｌｌ Ｍｉｌｌｉｎｇ ＴｉｍｅTX１ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｈａｓｂｅｅｎｒｅｃｅｎｔｌｙｒｅｐｏｒｔｅｄｔｈａｔｎａｎｏｃｒｙｓｔａｌｉｎｅｍａｔｅｒｉ...     

Magnetic Properties of Nanocrystalline Fe_(60)Cr_(40) Powders Prepared by Mechanical Alloying in Vacuum and Air

1　Introduction　Sincethediscoveryofgiantmagnetoresistance(GMR),magneticmaterialswithrandommixtureofferromagneticandantiferromagneticpropertieshaverecentlyrecievedalotofattention[1].ThemagneticpropertiesofFeandCrarequitedifferentfromeachother.Feisferromagneticbelow1043K,whileCrisantiferromagneticatroomtemperature.GMRexistesnotonlyinsandwichandmultilayerfilms,butalsoinothernanostructuralmaterials,suchasgranularfilmsandnanostructurebulkmaterialspreparedbymechanicalalloying(MA).MAhasbeendev…     

Magnetic Properties of Nanocrystalline Fe60Cr40 Powders Prepared by Mechanical Alloying in Vacuum and Air

Magnetic properties of nanocrystalline Fe60 Cr40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and ^67Fe M（oe）ssbauer spectrum. The results show that the Fe60 Cr40 powders keep the bcc structure during milling in air and vacuum. The saturation magnetization of the Fe60 Cr40 powders milled in vacuum and air decreases with the increase of the milling time up to 45 h. The decrease of saturation magnetization of the Fe60Cr40 powders milled in vacuum is due to the formation of Fe-Cr solid solution, while in air it is due to the formation of paramagnetic disorder structure and solid solution.     

影响铁基纳米晶Fe73.5Cu1Nb3Si13.5B9合金微观结构相及软磁特性的因素

通过三个实验的对比研究得出结论,退火温度Ta、退火加热速度、外加磁场的强度、外加磁场的频率以及纳米晶合金材料的工作温度等外界条件都是影响纳米晶Fe73.5Cu1Nb3Si13.5B9合金微观结构相和软磁特性的因素。其中退火温度是决定性的因素。同时表明,工作温度也是决定纳米晶合金软磁性能优劣和稳定的先决条件。     

均匀沉淀法制备Ba1-xSrxTiO3介电材料

利用四氯化钛、氢氧化钡、氢氧化锶及氨水为原料,采用均匀沉淀法制备了Ba1-xSrxTiO3超细粉体.通过XRD物相分析,产品为立方晶系的完全固溶体,结果符合Vegard定律.TEM形貌观察,粒子为均匀球形,平均粒径小于100nm.用所合成的粉末压片,1200℃烧结即可得致密烧结体,介电常数6700,介电损失较纯钛酸钡有所降低.