快淬Nd－Fe－B合金的磁性研究

分析了快淬Ｎｄ－Ｆｅ－Ｂ合金的磁性能与合金成分和制备工艺的关系。着重阐述了合金冷却速度、退火温度等工艺对快淬Ｎｄ－Ｆｅ－Ｂ％金的磁能积、矫顽力、居里温度等性能的影响，并给出了最佳工艺条件     

添加钴和铜的Nd－Fe－B型烧结磁体

添加钴和铜的Ｎｄ－Ｆｅ－Ｂ型烧结磁体为提高Ｎｄ－Ｆｅ－Ｂ型磁体的矫顽力，改善磁体的温度稳定性和耐蚀性，进行了复合添加钻、铜对Ｎｄ－Ｆｅ－Ｂ型磁体磁性能影响的实验。实验的合金为（Ｎｄ．Ｄｙ）－（Ｆｅ、Ｃｏ、Ｃｕ）－Ｂ，由真空感应炉熔炼，熔体用氯气雾化成...     

Fe-Nb-R-B纳米晶和Fe-Zr-R-B合金的磁特性

Ｆｅ－Ｎｂ－Ｒ－Ｂ纳米晶和Ｆｅ－Ｚｒ－Ｒ－Ｂ合金的磁特性非晶合金通过热处理能获得以ｂｃｃ－Ｆｅ相为主相的１０～２０ｎｍ左右微晶，这种Ｆｅ－（Ｚｒ，Ｎｂ）－Ｂ合金，具有１．５～１．７Ｔ高饱和磁感。这种材料和硬磁性纳米晶Ｆｅ－（Ｎｄ，Ｐｒ）－Ｂ合金复合，...     

氢对Nd-Fe-B-H化合物磁性的影响

氢对硬磁相Ｎｄ２Ｆｅ１４Ｂ的磁性能、机械性能和化学性能影响很大,其影响机理主要表现在以下两个方面：①由于氢使Ｎｄ２Ｆｅ１４Ｂ晶体点阵参数和电子结构的变化,从而影响了ＮｄＦｅＢ合金的磁性、居里温度和磁各向异性。②当ＮｄＦｅＢ合金在氢气中加热到６５０℃以上时, Ｎｄ２Ｆｅ１４Ｂ分解为 Ｆｅ、ＮｄＨ２和Ｆｅ２Ｂ。第１种影响机理可以控制氢浓度,以便得到最佳的磁特性,而第２种影响机理可以提供高矫顽力。Ｋｒｏｎｍｌｌｅｒ及其同事研究了包含各种氢爆烈破坏的Ｎｄ－Ｆｅ－Ｂ磁体的显微组织和磁畴结构,发现矫顽力对晶粒…     

添加Ti+C对Nd9Fe85B6的可淬性和磁性的影响

数年前就已发现添加Ｔｉ或Ｃ或同时添加Ｔｉ Ｃ ,可大大提高Ｎｄ2 Ｆｅ14Ｂ合金的玻璃化形成能力 ,有可能应用于生产气体雾化Ｎｄ Ｆｅ Ｂ粉末。如果添加Ｔｉ Ｃ也能够改进α Ｆｅ/Ｎｄ2 Ｆｅ14Ｂ合金的玻璃化形成能力 ,并且对其磁性能无任何影响 ,将有助于其工业化生产。因此 ,研究了添加Ｔｉ Ｃ及添加量对于Ｎｄ9Ｆｅ85 Ｂ6 合金的玻璃化形成能力和磁性能的影响。研究用的合金是用纯钕 (纯度 99.95 % )、纯铁 (纯度 99.99% )、纯钛 ( 99.97% )、光谱纯碳和硼铁 (Ｂ含量1 9 6 % )合金为原料 ,在超纯氩气氛中经等离子弧熔炼制得的Ｎｄ9Ｆｅ…     

Fe_3B/Nd_2Fe_(14)B纳米复合永磁厚带

研究了快淬条件,特别是熔体旋淬室的气压和快淬铜辊的表面速度对Ｆｅ３Ｂ／Ｎｄ２Ｆｅ１４Ｂ纳米复合磁体的微结构和磁性能的影响．用单辊快淬技术制备了Ｎｄ４Ｆｅ７７．５Ｂ１８．５和Ｎｄ３．５Ｄｙ１Ｆｅ７３Ｃｏ３Ｇａ１Ｂ１８．５合金．熔体快淬室的Ａｒ气压力Ｐ为１．３～９５ｋＰａ,快淬铜辊的表面速度Ｖｓ处于２～３０ｍ／ｓ．用差示热分析和Ｘ射线衍射分析研究样品的微结构,用扫描电镜研究快凝合金的表面状态,用振动样品磁强计测量材料的室温磁性．结果表明,对于Ｎｄ４Ｆｅ７７．５Ｂ１８．５合金,当Ｖｓ５ｍ／ｓ、Ｐ＝７５…     

Nd—Fe—B永磁合金的腐蚀特性

德国德累斯顿固体材料研究所的Ｌ．Ｓｃｈｕｌｙ及其同事研究了Ｎｄ－Ｆｅ－Ｂ永磁合金及其单相在室温下硫酸溶液中和１５０℃潮湿空气两种介质中重量的变化和电化学工艺．揭示了这类合金及其单相静电表面势能与腐蚀速率的关系．试验所用的单相材料为：Ｎｄ２Ｆｅ１４Ｂ（相,铁磁相）、Ｎｄ１＋３Ｆｅ４Ｂ４（相,富硼相）和Ｎｄ４Ｆｅ４（ｎ相,富钕相）。合金材料是采用四种不同方法制备的,其化学成分也不同,四种方法分别为：ＨＤＤＲＩ法（氢化脱氢再化合１法,Ｎｄ１５Ｆｅ４４Ｂ８）、ＨＤＤＲⅡ法（氢化脱氢再化合２法,Ｎｄ１３.…     

纳米晶Nd－Fe－Bg合金的磁性与微结构

纳米晶Ｎｄ－Ｆｅ－Ｂｇ合金的磁性与微结构熔体快淬Ｎｄ—Ｆｅ－Ｂ基合金带的微结构和磁性强烈地依赖于合金成分和快淬条件。传统工艺制造的合金带为各向同性微晶结构，晶粒尺寸处于５０～１００ｎｍ。这种材料具有高的矫顽力１Ｈｃ，但剩磁Ｊｒ小于Ｊ０／２（Ｊ．为饱和...     

Nd2Fe14B／α—Fe纳米晶双相复合永磁合金

采用快淬火及热处理工艺,通过复合添加Ｄｙ和Ｇａ,制备了高磁性能的Ｎｄ２Ｆｅ１４Ｂ／α－Ｆｅ纳米晶双相复合永磁合金,合金最佳磁性能为,Ｊｆ＝１．１６１Ｔ（１１．６ｋＧｓ）,Ｈｃｉ＝５８０．５０ｋＡ／ｍ（７．３０ｋＯｅ）和（ＢＨ）ｍａｘ＝１６２．７ｋＪ／ｍ＾３（２０．５ＭＧｓ．Ｏｅ）。该合金成分为Ｎｄ７．５Ｄｙ１Ｆｅ８５Ｂ４．５Ｇａ２,其显微组织由晶粒尺寸约为３２ｎｍ的硬磁相Ｎｄ２Ｆｅ１４Ｂ和１６ｎｍ     

氧对Nd－Fe－B型烧结磁体磁性和热稳性的影响

氧对Ｎｄ－Ｆｅ－Ｂ型烧结磁体磁性和热稳性的影响、通常认为，氧对Ｎｄ－Ｆｅ－Ｂ型烧结磁体的磁性能是有害的。美国柑润材料公司系统地研究了氧对不同类型Ｎｄ－Ｆｅ－Ｂ磁体磁性和热稳定性的影响。实验选用的材料包括含铅的（Ｎｄ，Ｄｙ）－（Ｆｅ，Ｃｏ）－Ｂ系和不含...     

烧结Nd—Fe—B永磁体化学镀Ni—Cu—P性能研究

通过适当的预处理工艺,在烧结Nd-Fe-B永磁体表面直接实用化学镀Ni-Cu-P,不需要预镀处理,用X－射线衍射仪,扫描电镜分析与镀层的结构和表面形貌、测试了镀层的耐蚀性能和结合强度。结果表明,Nd-Fe-B永磁体经化学镀Ni-Cu-P后,可以获得与基体结合良好,孔隙率低、耐蚀性高的镀层。     

富钕相对烧结NdFeB磁体耐腐蚀性的影响

研究了Nd2Fe14B单晶、传统烧结NdFeB磁体和放电等离子烧结（简称SPS）NdFeB磁体在电解液溶液中的电化学特性。采用扫描电子显微镜和电子能谱分析了磁体的微观组织成分。结果表明在3．5％NaCI溶液的极化曲线中，Nd2Fe14B单晶具有最高的电化学腐蚀电位，放电等离子烧结NdFeB磁体的腐蚀电位高于传统烧结NdFeB磁体。与传统烧结NdFeB磁体相比，放电等离子烧结NdFeB磁体富Nd相具有独特的分布形态，主相Nd2Fe14B晶粒细小、均匀，富钕相在主相晶粒边界上分布较少，主要集中在三角晶界处。这种组织结构有效地抑制了磁体沿富钕相发生晶间腐蚀的过程，磁体因此具有良好的耐腐蚀性能。此外，从不同稀土含量的烧结NdFeB磁体的高压加速实验中可以看出磁体的腐蚀速度随稀土含量的增加而增大。以上结果表明富Nd相的化学特性及其分布状态和含量是决定合金耐蚀性能的关键，它在合金中以网络状分布在主相晶粒边界上，并决定了烧结NdFeB易于发生选择性晶间腐蚀，从而导致耐蚀性差。     

高矫顽力的低钕Nd9(FeCoZrAl)85B6纳米晶合金的制备

采用单辊快淬工艺制备了一种低钕含量Ｎｄ９（ＦｅＣｏＺｒＡｌ）８５Ｂ６纳米晶合金,研究了快淬工艺与热处理工艺对该合金纳米晶的形成及磁性的影响。结果表明快淬速度和热处理温度都明显地影响低钕含量Ｎｄ９（ＦｅＣｏＺｒＡｌ）８５Ｂ６纳米晶的形成及其磁性（内禀矫顽力ｊＨｃ,矫顽力ｂＨｃ,剩磁Ｂｒ和最大磁能积（ＢＨ）ｍ）。快淬速度２３ｍ／ｓ制备的非晶态合金,在６８５℃处理３０ｍｉｎ,可获得最佳的磁性,其粘结磁体的密度为６．０１ｇ／ｃｍ３时,Ｂｒ＝６５５ｍＴ,ｊＨｃ＝６３９．２ｋＡ／ｍ,ｂＨｃ＝３８１．６ｋＡ／ｍ,（ＢＨ）ｍ＝６５．６８ｋＪ／ｍ３。     

Korrosionsverhalten von Nd‐Fe‐B‐Dauermagneten

Corrosion behaviour of Nd‐Fe‐B permanent magnets The corrosion behaviour of Nd‐Fe‐B permanent magnetic alloys as well as of single phases of these alloys have been investigated in sulphuric acid at room temperature and humid air at 150 °C using mass loss and electrochemical techniques. Scanning electron microscopy and scanning probe microscopy were used to study the surface topography. The electrostatic surface potential was examined by scanning probe microscopy using tapping mode. A correlation between the electrostatic surface potential and the corrosion rate of these alloys was found. The higher the value of the electrostatic surface potential of the intergranular phases the higher is the corrosion sensitivity. The strength of the corrosion attack on the phases of sintered permanent magnetic alloys is as follows: Ferrmagnetic phase < B‐rich phase < Nd‐rich phase. The differences in the chemical composition as well as in the preparation of these magnetic alloys have distinct influence on the corrosion resistance of the magnetic Nd‐Fe‐B alloys.     

Corrosion resistance of Nd‐Fe‐B permanent magnetic alloys. Part 1: Role of alloying elements

The electrochemical behaviour of Nd‐Fe‐B magnetic alloys was investigated in acid and neutral solutions. The differences in the chemical composition of these materials have distinct influence on the corrosion rate and polarization behaviour. Small additions of cobalt, aluminium and gallium increase the corrosion resistance of the magnetic alloys at high cathodic potential. It was also observed that the increase of hydrogen evolution rate on the surface of the magnetic materials raises the rate of dissolution of these magnets. The electrostatic surface potential was examined by scanning probe microscopy. A relation between the electrostatic surface potential and electrochemical behaviour of these alloys was found. The high values of electrostatic surface potential of the intergranular phases reflect higher corrosion attack. Auger electron spectroscopy was used to analyse the surface layer which formed during anodic polarization of the magnet containing alloying additives. The result indicates the formation of (Nd,Fe)‐oxide with small amounts of cobalt and aluminium.     

Preparation and characterization of TiO_2/acrylic resin composite coatings on sintered NdFeB permanent magnets by electrochemical deposition

The sintered Nd Fe B permanent magnets are widely used in various industries because of their excellent magnetic and comprehensive properties. However, they are seriously hindered to further developments and applications owing to its poor corrosion resistance. In this paper,TiO2/acrylic resin composite coatings were successfully prepared on the sintered Nd Fe B permanent magnets by electrochemical deposition for the first time, and the corrosion behaviors were investigated by using immersion testing and potentiodynamic polarization tests. It is found that the coating is a composite, being composed of polymerized acrylic resin as the matrix and nano-rutile TiO2particles(-200 nm) as the reinforcements. It is about25 lm in thickness and its surface and cross-section exhibit uniform and smooth with no pores, cracks, and other defects. Compared with those of the uncoated Nd Fe B magnets, the weight loss of the coated samples immersed in H2SO4 solution reduces by two orders of magnitude,corrosion current density decreases by four orders of magnitude, and the corrosion potential of the coated sample is shifted in the noble direction by 400 m V. The mechanisms of corrosive resistance enhancement were discussed.     

Corrosion Resistance of Cordierite-Modified Light MMCs

Composites are one of the fastest developing materials. Research is particularly intensive in case of light metal alloys due to i.a. economic and environmental aspects. One of the innovative solutions is production of the metal matrix composites (MMC) by adding the cordierite ceramics obtained from fly ashes to magnesium alloys. In addition to obtaining new-generation materials with improved mechanical properties, also the waste is utilized which has a significant environmental and economic importance. In order to select the suitable operating conditions for such alloys, their corrosion resistance must be determined. This paper presents the results of corrosion resistance tests of AM60 magnesium alloy matrix composites reinforced with cordierite ceramics. The following issues were examined: (1) impact of the volume fraction of cordierite ceramics, 2 or 4 wt.%; (2) impact of surface roughness (two variants of surface treatment); and (3) impact of heat treatment on corrosion resistance of obtained composites. The results were compared with data recorded for the base AM60 alloy (which surface treatment was identical as of the composites). Moreover, the XRD and microanalysis of the chemical compositions by EDS method were applied to determine phases occurring in the investigated composites. Furthermore, the XRD was also performed in order to identify the corrosion products on the surface of the material. The test results indicate that the alloy reinforced with 2 wt.% addition of cordierite ceramics had the best corrosion resistance. It was also presented that surface and heat treatment affect the obtained results.     

化学镀Ni-Fe-P和Ni-Fe-P-B合金的耐蚀性研究

利用失重法和电化学测试法,对比研究以铝合金为基体化学镀Ni-Fe-P和Ni-Fe-P-B合金的耐蚀性.结果表明:这两种镀层浸泡在3.5%NaCl和10%NaOH溶液中均比浸泡在0.1mol/L H2SO4和1mol/L HCl中有更好的耐蚀性.另外,在3.5%NaCl和10%NaOH溶液中,Ni-Fe-P-B镀层合金比Ni-Fe-P有更好的耐蚀性;但是在0.1mol/L H2SO4和1mol/L HCl溶液中,Ni-Fe-P镀层合金却比Ni-Fe-P-B有更好的耐蚀性;     

Nd_2（Fe，Co）_（14）B／Nd_2（Fe，Co）_（17）双相HDDR

研究了由Ｎｄ_２（Ｆｅ，Ｃｏ）_（１４）Ｂ和Ｎｄ_２（Ｆｅ，Ｃｏ）_（１７）双相组成的ＨＤＤＲ高矫顽力磁粉的微观结构及磁性。发现在单相Ｎｄ_２（Ｆｅ，Ｃｏ）_（１４）Ｂ化合物的基础上降低Ｂ含量，导致Ｎｄ_２（Ｆｅ，Ｃｏ）_（１７）相出现，且随Ｂ含量降低该相逐渐增多．适量的Ｎｄ_２（Ｆｅ，Ｃｏ）_（１７）相的存在对用性有一定有益的作用，过量则导致磁性严重恶化，这可能与该相的尺寸和存在形式密切相关．     

单相纳米晶Nd12.3Fe79.2Nb2.5B6合金的交换耦合作用与显微组织

采用熔体快淬及晶化退火工艺制备了含铌单相纳米晶Nd12.3Fe79.2Nb2.5B6合金,研究添加Nb对单相Nd2Fe14B纳米晶合金的磁性能、交换耦合和微观结构的影响规律.结果表明:Nb的添加提高了合金的非晶热稳定性,使得合金最佳晶化温度升高;合金晶化退火后,Nb可使晶粒尺寸分布均匀,并得到单一Nd2Fe14B相;晶粒边界比较完整,存在共格、半共格或大角度晶界,但没有观察到晶界相.上述结构可有效提高合金的磁性能,增强交换耦合作用.通过对Nd12.3Fe79.2Nb2.5B6合金磁性能分析可知:650 ℃晶化退火10 min后的合金性能最佳,交换耦合作用最强.