共查询到20条相似文献，搜索用时 46 毫秒
1.
Shiyue Xu Hangde Chen Zhengming He Yaoming Shi Chuanhua Dong Zhengming Zhang 《上海大学学报(英文版)》1998,2(4):301-304
Nanocrystalline Fe25Ni75 powders were prepared by the mechanical alloying process. They were investigated by X-ray diffraction and magnetic measurements.
The ball milling time dependence of grain size, internal strain and magnetic properties has been discussed. The results show
that the formation of Fe25Ni75 alloy phase is almost completed after milling for 30 hours. The reduction of grain size accompanied by the growth of internal
strain was observed after extended milling. An average grain size about 10–20 nm of alloyed powders has been determined by
Sherrer formula estimation. The saturation magnetisation Ms has a slight increase when the average grain size continues to
decrease by intensive milling. This fine size of mechanically alloyed powders (10–20 nm) results in a single domain magnetic
structure and the formation of superparamagnetic phase. 相似文献
2.
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ ＵｌｔｒａｆｉｎｅｐａｒｔｉｃｌｅｓｏｆｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓｓｕｃｈａｓＦｅ,Ｃｏ,Ｎｉａｎｄｔｈｅｉｒａｌｌｏｙｓｈａｖｅｔｈｅｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎｓｉｎｍａｇｎｅｔｉｃｒｅｃｏｒｄｉｎｇ,ｆｅｒｒｏｆｌｕｉｄｓ,ｍｅｄｉｃａｌｄｉａｇｎｏｓｔｉｃｅｔｃ..Ｔｈｅｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓｏｆｆｉｎｅｐａｒｔｉｃｌｅｓｄｉｆｆｅｒｍａｇｎｉｆｉｃｅｎｔｌｙｆｒｏｍｔｈｏｓｅｏｆｌａｒｇｅｐａｒｔｉｃｌｅｓ,ａｎｄｔｈｅｒｅｌａｔ… 相似文献
3.
Shi-yue Xu Zheng-ming He Yao-ming Shi Zheng-ming Zhang Chuan-hua Dong Hang-de Chen 《上海大学学报(英文版)》2000,4(1):60-63
The magnetic anisotropy of Fe25Ni75 nanocrystallites in the range of 10∼20 nm was measured by the law of approach to saturation. The samples were prepared by
mechanical alloying process, and the average crystal size was determined by X-ray diffraction. The effective magnetic anisotropy
of these fine particles is found In an order of 106 erg/cm3 that is much greater than that of normal crystal size of particles. The dependence of magnetic anisotropy on the particle
size was studied. It has been demonstrated that the strain anisotropy occupies the most of the total magnetic anisotropy,
and the internal strain is a critical factor for their magnetic properties.
Supported by the Science Foundation of Shanghai Municipal Commission of Education (807965) 相似文献
4.
用高能球磨制备等原子比铁(Fe)钴(Co)镍(Ni)铁镍钴复合粉体,用激光熔覆方法制备复合粉铁镍钴体合金涂层。用OM、HV、XRD、SEM、EDS、SVET等对复合粉体及熔覆合金层进行了组织表征及性能测试。结果表明,复合粉体经3 h高能球磨后均匀细化,平均尺寸从35μm到15μm左右,镍晶格有一定畸变,有新相Co3Fe7产生;用优化后的激光熔覆工艺激光功率2000 W,激光扫描速度10 mm/s,保护Ar气流速度12 L/min制备中熵熔覆合金FeCoNi涂层;XRD、SEM、EDS表明熔覆层合金是单一的面心立方(FCC)相,Fe,Co,Ni成分均匀分布,没有金属间化合物产生;熔覆层的HV约是243,在0.5 mol/L氯化钠溶液中熔覆层的SVET表明耐腐蚀性能好。 相似文献
5.
采用化学溶液沉积法在Si(001)衬底上制备Ni0.7Zn0.3Fe2O4铁氧体薄膜,XRD谱表明样品具有单相的尖晶石结构;扫描电子显微镜结果表明样品平均颗粒尺寸随着退火温度的上升从10 nm增加到32 nm。NZFO铁氧体薄膜磁性能与退火温度有强烈的依赖关系,薄膜的矫顽力从退火温度为500℃时的25 Oe增加到900℃时的80 Oe,饱和磁化强度也由146emu/cm3增加到283 emu/cm3,这对于现代电子器件微型化有着非常重要的意义。 相似文献
6.
水解沉淀法制备纳米TiO2及其表征 总被引：1，自引：0，他引：1
以TiOSO4为原料制备纳米TiO2 并对其进行XRD、BET、TEM研究 .结果表明 ,pH值与热处理温度对晶粒大小及晶型结构有很大影响 .在 5 0 0℃热处理条件下 ,pH =5时的纳米粉末比表面积为 10 1.3 9m2 ·g-1,粒径 10nm左右 ;pH =10时的纳米粉末比表面积为 95 .48m2 ·g-1,粒径 3 0nm左右 .在 75 0℃时的金红石晶型转变对粒径的长大有很大的促进作用 . 相似文献
7.
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. 相似文献
8.
郭宝会 《渭南师范学院学报》2010,25(2):24-27
探讨了显微组织对纳米复合永磁材料的矫顽力、剩磁和最大磁能积的影响.得出了要同时得到良好的磁性能,要综合考虑晶粒尺寸和软磁性含量.设计纳米复合磁体的原则应该是：软磁相和硬磁相的晶粒尺寸分别控制在10nm和20nm左右,软磁性体积百分比控制在30%~40%之间,而且两者之间充分交换耦合. 相似文献
9.
1IntroductionIt is well known that the solubility of carbon in Fefor both body-centered-cubic (bcc) and face-centered-cubic (fcc) structures is very low, even in a liquidstate. The maxi mum solubility of carbon in ferrite isonly about 0 .1 atompercent .The difference of atomicradius between Fe and C is so large that C is em-bedded at the interstitial site in the bcc or fcc Fe lat-tice . Hume-Rothery rules suggest that the atomic sizeof the solute and solvent should differ by less than15 %to… 相似文献
10.
The Mg-based hydrogen storage alloys Mg2Ni, Mg2Ni0.7Fe0.3 and Mgl.7Alo.3Ni were successfully synthesized by a two-step process （sintering and ball milling）. The crystal structure and microstructure were examined by X-ray diffraction, Scanning Electron Microscope and Malvern particle size analyzer. New phase appears in the tripe alloys doped with A1 and Fe, and the particle size ranges from 3μm to 5 μm. The electrochemical performance studies indicate that the partial substitution of AI for Mg, and Fe for Ni significantly improve the cycle life, reversibility of hydrogen absorption and desorption. The diffusion process is the control step in the electrode reaction of hydrogen storage alloys. 相似文献
11.
王梦瑜 《安徽教育学院学报》2011,29(3):26-31
本文采用溶胶凝胶自燃烧法制备了粒径在200~300nm的单相六角铁酸钡粉体,并对其进行球磨,外加PEG-20000为分散剂,调节料浆的pH值等手段对六角铁酸钡磁性颗粒进行分散,研究表明球磨过程中磁性颗粒经历了团聚后打开,然后有形成诸如磁链、磁环等磁结构的过程。对六角铁酸钡进行干压（未加磁场和加磁场）以及磁场下悬浮-沉降等工艺成型,经过压力和磁场的作用得到的块材沿易磁化方向具有一定的取向。磁性测试结果表明：球磨前后的粉体比磁化强度（1.5T）从40.3emu/g上升到了51.5emu/g,这个数值接近铁酸钡单晶磁化强度,矫顽力从4.1kOe小幅度提高到4.3kOe。悬浮-沉降成型比磁化强度（1.0T）就达到了48.4emu/g,而矫顽力有明显下降。 相似文献
12.
1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｆｅ Ｎｉａｌｌｏｙｉｓｗｉｄｅｌｙｕｓｅｄａｓｓｏｆｔｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓｆｏｒａｌｏｎｇｔｉｍｅ .Ｉｔｓｍａｇｎｅｔｉｃｐｒｏｐｅｒｔｉｅｓａｓｉｎｉｔｉａｌｐｅｒｍｅ ａｂｉｌｉｔｙμｉａｎｄｃｏｅｒｃｉｖｉｔｙｆｏｒｃｅＨｃｄｅｐｅｎｄｓｔｒｏｎｇｌｙｏｎｔｈｅｃｈｅｍｉｃａｌｃｏｍｐｏｓｉｔｉｏｎａｎｄｔｒｅａｔｍｅｎｔｌｉｋｅｑｕｅｎｃｈｉｎｇｆｒｏｍｈｉｇｈｔｅｍｐｅｒａｔｕｒｅ .Ａｓｕｌｔｒａｆｉｎｅｐａｒｔｉｃｌｅｉｓｒｅｖｅａｌｅｄｒ… 相似文献
13.
WANG Xiu-li TU Jiang-ping ZHANG Pei-long ZHAO Xin-bing 《浙江大学学报(A卷英文版)》2007,8(9):1510-1513
Mg-25 wt% Mg2Ni composite was prepared by sintered method,hydrided at 613 K and then ball-milled with 1.5 wt% PdCl2 additive for 51 h. The effects of PdCl2 on the hydriding and dehydriding behavior of Mg-25 wt% Mg2Ni composite were investigated. The absorption and desorption rate of the composite with PdCl2 is fast and the hydrogen storage capacity is more than that of the composite without PdCl2. The maximum hydrogen storage capacity reached 3.48 wt% at 373 K,and 5.05 wt% H at 453 K,respectively. The improvement of sorption and desorption kinetics is attributed to the catalytic effect of PdCl2,and the grain refining and lattice strain introduced by ball milling. 相似文献
14.
采用溶胶-凝胶法制备不同粒径的La缺位La0.9MnO3钙钛矿氧化物.用X射线衍射、扫描电子显微镜、振动样品磁强计对材料的晶体结构、微结构、磁性和磁热效应进行了研究.结果表明,不同温度下退火(700oC~1100oC)的样品均具有菱形钙钛矿结构.退火温度从700oC增加到1100oC,样品的平均晶粒大小从25 nm增加到1000 nm.随着晶粒大小的增加,材料在低温的饱和磁化强度逐渐增强,铁磁到顺磁的相变变得陡峭,从而使材料的磁熵变逐渐增加.当材料的晶粒尺寸大于500 nm时,材料的磁熵变趋于稳定(-2.7 J/kg·K). 相似文献
15.
用两种不同沉淀剂制备了纳米Fe3O4磁性粒子,对二种工艺的主要反应条件进行了比较研究,都制备出了粒子尺寸为8~12 nm,正态分布比较好的粒子。一、25%NH3.H2O(A.R.)作为沉淀剂和pH值的调节剂,pH≥9,Fe3+/Fe2+的物质的量之比的值约为1.75,反应时间为1h,温度控制在40℃。搅拌速度为1 500 r/min;二、3mol/L氢氧化钠溶液作为沉淀剂,碱过量25%,Fe3+/Fe2+的物质的量之比约为2∶1.2,反应时间为1 h,反应开始时温度为70℃,反应10 min后将温度降至50℃,再反应50 min。搅拌速度为1 500 r/min。产品的铁含量接近理论值,干粉的磁化率也较理想。 相似文献
16.
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. 相似文献
17.
本文通过测量Co3Ti、 Ni3Al、 Fe3Al、 TiAl四种金属间化合物在氧气、氢气中在2×10-4/s形变速率下的拉伸性能，研究了
其在氢气中的室温环境脆性.研究结果表明，上述四利金属间化合物在H2中的脆化程度(用氢脆因子
IH2=[(δo2一δH2)/δo2]×100％表示)是不同的，其大小依次为Co3Ti＞Ni3 Al＞Fe3Al＞TiAl.其脆化程度的差异用金属间化合物中
基体金属对氢气的催化裂解作用的强弱进行了很好的解释. 相似文献
18.
通过固相反应法制备非磁性原子Ti掺杂ZnO系列样品．X射线衍射测量显示样品除了ZnO相外,还产生了Zn2TiO4、ZnTiO3两个物相．晶粒大小为30～60nm．振动样品磁强计测量得出样品的磁性都为抗磁性．样品电阻率大于l02Ω·cm,无霍尔效应和磁致电阻效应． 相似文献
19.
以壳聚糖为分散剂,用化学共沉淀法制备Fe3O4磁性粒子,通过多次实验总结出最佳工艺条件:反应液的初始浓度为Fe3+0.15 mol/L,Fe3+/Fe2+(物质的量)之比在1.70~1.75之间;25%NH3.H2O作为沉淀剂,并过量20%~30%,溶液pH=9~11;反应温度35℃,反应时间60 min,搅拌速度3 000 r/min。用壳聚糖作分散剂,其最佳用量为每60 mL载液0.040 0 g,温度控制在50℃左右,在pH值为1.0的条件下进行包覆。在该条件下制得的壳聚糖磁性微球放置17个月,无明显分层现象。利用了IR、TG-DTA和紫外可见分光光度法等方法对产品进行了表征。 相似文献
20.
以碳酸氢铵为沉淀剂,采用化学共沉淀法合成出多晶Nd：YAG纳米陶瓷粉体．采用XRD,SEM,BET等测试手段对粉体的相组成和微观结构进行表征,研究了煅烧温度、反应温度、Al（NO3）3浓度对粉体形貌、粒径以及分散性的影响．结果表明：前驱体在900℃煅烧2h直接生成Nd：YAG,并且随着煅烧温度的升高,粉体粒径逐渐变大,1100℃时煅烧所得粉体的平均粒径约为70nm．反应温度为30～40℃、硝酸铝溶液浓度为0．1～0．2mol／L时,所得粉体为球形或类球形,分散性最佳． 相似文献