Nanocrystal Growth in Thermally Treated Fe75Ni2Si8B13C2 Amorphous Alloy

Thermal treatment of amorphous Fe₇₅Ni₂Si₈B₁₃C₂ alloy leads to crystallization of the stable ??-Fe(Si) and Fe₂B as well as to the metastable Fe₃B phase. The study of the mechanism of crystal growth of the ??-Fe(Si) phase revealed that the mechanism of ??-Fe(Si) growth changes from two dimensional in the early stage to one dimensional in the later stage of crystallization. The Fe₂B phase was found to crystallize through two independent routes: from the amorphous phase and from the metastable Fe₃B phase, which leads to a different mechanism of crystal growth for each route. Both routes exhibit a change in the mechanism of crystal growth: from two dimensional to one dimensional and from three dimensional to two dimensional, respectively. The respective mechanisms of crystal growth correlate well with the observed changes in preferential orientation of the crystallites of the Fe₂B phase.     

Fe73.5Cu1Nb3Si13.5B9非晶合金晶化过程的研究

用动态及等温差示扫描量热计（ＤＳＣ）研究非晶合金Ｆｅ７３．５Ｃｕ１Ｎｂ３Ｓｉ１３．５Ｂ９在制备态及经预退火后的晶化行为。在制备态，合金的有效晶化激活能Ｑ＝３８４ｋＪ／ｍｏｌ，Ａｖｒａｍｉ因子ｎ＝１．５￣１．７。经过至５１０℃的预退火，Ｑｅ上升到４９４ｋＪ／ｍｏｌ。经过４００℃预退火后ｎ值变化不大，而等温晶化的激活能Ｑ（ｘ）上升了２０￣５０ｋＪ／ｍｏｌ。     

喷射成形FINEMET合金Fe73.5Cu1Nb3Si13.5B9的研究

用喷射成形法制备了Fe73.5Cu1Nb3Si13.5B9（at％）的铁基非晶合金,目的在于研究非晶相的形成机理及其在高速冷却条件下生成特定的微观结构。喷射成形气流中,G／M为0．15,雾化气体为氮气。所得到的沉积体和过喷粉末的粒径在5μm左右,总重约2．2kg。借助X射线衍射（XRD）、光学显微镜（OM）以及透射电镜（TEM）等分析方法研究了沉积体的微观组织结构。发现随着厚度的改变,其成分、结构也有所变化,体现在中心区域厚度15mm和边缘区域厚度8mm的孔隙率分别为4％和9％。中心较厚区域为晶粒尺寸250nm左右的完全晶化相,而边缘较薄区域则有部分非晶相,其晶粒尺寸在40nm。由XRD谱线分析,过喷粉末为完全晶化相,用谢利方程（Scherrer formula）分析得到其晶粒在80nm左右。通过VSM分析,其软磁性能很差,饱和磁感只有0．3～0．6T,同时矫顽力上升得很快。     

非晶Fe73.5Cu1Nb3Si13.5B9合金的纳米晶化动力学研究

根据不同升温速率的DSC曲线,通过非等温DSC方法和TEM方法研究了Fe73.5Cu1 Nb3 Si13.5 B9合金的纳米晶化行为.通过非基于模型的方法,得出了多组激活能Ea和晶化分数α数据,Eα的平均值为368±30kJ/mol.这表明晶化过程不符合JMA模型,而Sestak-Berggren方程适用于该过程.SB方程的动力学参数m和n分别为0.36±0.04和1.52±0.05,揭示了晶相动力学和形核及生长过程中的机制.通过比较实验数据和标准数据验证了动力学参数m和n的准确性.     

逆变焊机用Fe_(73.5)Cu_1Mo_3Si_(15.5)B_7超微晶合金的软磁性能

对比了Fe73.5Cu1Mo3Si15.5B7超微晶合金和目前逆变焊机主变压器普遍采用的Fe73.5Cu1Nb3Si15.5B7铁芯的静态和动态磁性能。重点研究了两种材料铁芯的饱和磁致伸缩系数、10~40kHz范围内的高频性能和脉冲性能、-40~140℃间的损耗及磁导率变化。研究结果表明,Fe73.5Cu1Mo3Si15.5B7铁芯可获得低的高频损耗、高磁导率、较低的饱和磁致伸缩系数及良好的温度稳定性,满足逆变焊机主变压器对铁芯材料的要求,同时,Fe73.5Cu1Mo3Si15.5B7带材韧性更高,可改善材料制备的工艺性能和快淬带材的力学性能,提高成材率。     

Nd11Fe71Co8V1.5Cr1B7.5合金结构与磁性能的研究

采用熔体快淬及晶化处理工艺制备Nd11Fe71Co8V1.5Cr1B7.5纳米晶合金. 运用XRD, DTA等方法研究了快淬工艺与热处理工艺对该合金纳米晶形成、晶化过程及磁性能的影响. 结果表明, 快淬速度和热处理温度都明显地影响Nd11Fe71Co8V1.5Cr1B7.5纳米晶的形成及其磁性能; 该合金在晶化过程中先后出现了3个放热峰, 分别对应软磁相α-Fe, 亚稳相和硬磁相Nd2Fe14B 3个晶化相. 快淬速度21 m*s-1制备快淬薄片经640 ℃/4 min晶化处理后, 制成的粘结磁体的最佳磁性能为 Br=0.64 T, JHc=903.5 kA·m-1, (BH)max=71 kJ·m-3.     

Local Composition Migration Induced Microstructural Evolution and Mechanical Properties of Non-equiatomic Fe40Cr25Ni15 Al15Co5 Medium-Entropy Alloy

A newly designed composition of non-equiatomic Fe₄₀Cr₂₅Ni₁₅Al₁₅Co₅ medium-entropy alloy (MEA) was produced by induction melting (IM). The as-cast alloy was found to consist of a two-phase microstructure of BCC (2.87 ± 0.01 Å) and ordered B2 (2.88 ± 0.02 Å) type phases. The structures of these phases were confirmed through X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. It was observed that the Ni-Al-enriched ordered B2 phase of cuboidal shapes (~ 100 to 200 nm) is homogeneously distributed in Fe-Cr-rich BCC matrix with a cube-on-cube orientation relationship. The formation of the columnar dendrites (width 50 to 100 μm) was identified through optical microscopy (OM). The structural and microstructural stability of the alloy was investigated by heat-treating the alloy through different schedules. Heat-treated samples at different temperatures (< 1273 K) exhibit a similar type of two-phase microstructure with columnar dendrites. However, compositional rearrangement takes place during long time exposure to develop polymorphically related phases. The alloy was observed to possess a high compressive yield strength and hardness, i.e., ~ 1047 MPa and 391 ± 9 HV, respectively, at room temperature. Heat-treated samples at 600 °C and 900 °C (873 K and 1173 K) showed an increase in yield strength and ultimate strength with a significant increase in plasticity due to the increase in volume fraction of B2 phase and softening of the BCC matrix phase. The thermal stability and high strength of this alloy may open new avenues for high-temperature applications.

     

FINEMET合金Fe73.5Si13.5B9Cu1Nb3不同状态微观结构研究进展

综述了FINEMET合金在液态、淬火非晶态和不同晶化状态时的微观结构研究现状.研究表明,该合金液态结构由多种原子团簇组成,符合微观不均匀模型;合金淬火态非晶组织含有尺寸约为2nm的微观不均匀区域;在低温(<450℃)退火处理时从淬火非晶态到纳米晶态的转变已经发生.基于Cu和Nb两种元素的作用,总结了该合金的晶化机制合金液态、非晶态和纳米晶态的微观结构之间具有相关性.     

Study on Annealing Embritlement of Fe-B-Si Amorphous Alloy

ＳｔｕｄｙｏｎＡｎｎｅａｌｉｎｇＥｍｂｒｉｔｌｅｍｅｎｔｏｆＦｅ┐Ｂ┐ＳｉＡｍｏｒｐｈｏｕｓＡｌｏｙＣａｏＸｉｎｇｇｕｏ①，ＧｕｏＺｅｃｈｅｎ①，ＣｈｅＸｉａｏｚｈｏｕ②，ＬｉｕＰｉｎｇ①，ＹｉｎＢｉａｏ①ＡＢＳＴＲＡＣＴＴｈｅｌａｗａｎｄａｃｔｉｖ...     

Microstructure Variation of Nd_(15)Fe_(77)B_(8) Alloy in Hydrogenation-Disproportionation-Desorption-Recombination Process

ＭｉｃｒｏｓｔｒｕｃｔｕｒｅＶａｒｉａｔｉｏｎｏｆＮｄ１５Ｆｅ７７Ｂ８ＡｌｏｙｉｎＨｙｄｒｏｇｅｎａｔｉｏｎＤｉｓｐｒｏｐｏｒｔｉｏｎａｔｉｏｎＤｅｓｏｒｐｔｉｏｎＲｅｃｏｍｂｉｎａｔｉｏｎＰｒｏｃｅｓＬｉＬｏｎｇ（李隆），ＬｕｏＫａｎｃｈａ...     

Sm8Fe85Si2C5非晶合金的晶化动力学

用差热分析,结合Ｘ射线衍射研究了Ｓｍ８Ｆｅ８５Ｓｉ２Ｃ５非晶合金的晶化动力学。试验结果表明：在０－９００℃,该合金晶化相和Ｓｍ２（ＦｅＳｉ）１７Ｃｘ在晶化初激活能变化不大,当晶化量Ｘｃ（ａ－Ｆｅ）大于７０％、Ｘｃ「Ｓｍ２（ＦｅＳｉ）１７Ｃｘ」大于５０％时,两相晶激活能开始减小。     

(Ni0.75Fe0.25)70Zr8Si10B12非晶合金非等温晶化行为研究

采用旋铸急冷工艺在真空条件下制备出(Ni0.75Fe0.25)70Zr8Si10B12合金条带.经X射线衍射(XRD)分析表明样品为完全非晶.用Diamond TG/DTA差热分析仪在高纯氩气保护下测量了非晶薄带的热稳定性参数玻璃转变温度Tg、晶化起始温度Txi、晶化峰值温度Tpi.选用不同的升温速率,即10,20,30,40 K·min-1研究其晶化行为.结果表明,随升温速度的增大,特征温度Tg,Txi,Tpi均向高温区移动,其玻璃转变与晶化行为都与加热速率有关,均具有动力学效应.应用Kissinger法与Ozawa法研究了(Ni0.75Fe0.25)70Zr8Si10B12非晶合金的非等温晶化动力学行为.计算了不同特征温度下的激活能E、频率因子,用Kissinger法和Ozawa法计算的激活能结果是一致的.     

Fe73.5 Cu1 Nb3 Si13.5 B9非晶合金的激光晶化

用CO2连续激光在不同功率、相同的速度条件下辐照Fe73.5Cu1Nb3Si13.5B9非晶带，然后用穆斯堡尔谱详细研究材料的微观结构。研究发现当扫描速度和散文斑直径一定的情况下，适当选择激光功率，Fe73.5Cu1Nb3Si13.5B9可以实现微量晶化。     

Fe74Al4Sn2P10Si484C2合金的堆焊层组织和性能

Fe74Al4Sn2P10Si4B4C2合金具有良好的非晶形成能力.研究了Fe74Al4Sn2P10Si4B4C2母合金棒堆焊层的组织和性能.结果表明在非晶纳米晶基体上分布着α-Fe固熔体以及析出的Fe3P、Fe2B、Fe3B、Fe3C相,堆焊层具有很高的硬度.     

Fe74Al4Sn2P10Si4B4C2合金的堆焊层组织和性能

 Fe74Al4Sn2P10Si4B4C2合金具有良好的非晶形成能力。研究了Fe74Al4Sn2P10Si4B4C2母合金棒堆焊层的组织和性能。结果表明：在非晶纳米晶基体上分布着α Fe固熔体以及析出的Fe3P、Fe2B、Fe3B、Fe3C相,堆焊层具有很高的硬度。     

Localized vs homogeneous deformation in Fe82B15Si3 amorphous alloy

Amorphous alloys are known to deform plastically either by a localized shear mode or in a homogeneous manner. Conditions that favor homogeneous deformation in an amorphous alloy consisting of 82Fe, 15B and 3Si in at. pct have been established by a free-bend test over a range of temperatures. These results are in turn related to the stress-strain rate-temperature relationship obtained by a load relaxation testing method. The intense, localized shear deformation is shown to occur at relatively high strain rate and low temperature regions where the rate sensitivity of flow stress,m, is small. With increasingm, plastic flow tends to take place homogeneously provided that the mode of deformation remains stable. The strain rate sensitivity of flow stress increases with decreasing strain rate and increasing temperature; the computed diffuse shear transformation zone also changes in the same manner. However, the general trend changes above the glass transition temperature, i.e., the diffuse shear transformation zone decreases and the flow strength increases with increasing temperature.     

Influence of Heat Treatment on Microstructures and Properties of Nd8Fe78B6Co4 Alloy

Melt-spun Nd8Fe78B6Co4 magnetic powders and their bonded magnets were prepared with the optimization of compositions and preparation techniques. The microstructure change of alloy NdFeB and the relation between microstructure and heat-treatment were studied. The heat-treatment temperature is 200～700 ℃. The as-cast structure of the alloy is typically amorphous. Different melt-spun speed and different heat treatment could result in different magnetic properties of NdFeB magnets. Magnetic properties of NdFeB increase with the addition of element Co. The magnetic properties of magnet alloy get the best when the melt-spun speed reaches 23～26 m·s-1, heat treatment temperature is 690 ℃ and time is 30 min.