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纳米双相复合稀土永磁材料,利用硬磁相高磁晶各向异性和软磁相高饱和磁化强度的优点,通过铁磁交换耦合作用获得优异的磁性能.但是如何解决软硬磁双相纳米微结构不匹配的问题,控制软硬磁相同时达到理想的纳米尺度复合是关键.本文研究了掺杂合金元素Ti对熔体快淬法制备的Nd2Fe14B/α-Fe快淬薄带晶化过程的影响.结果表明,掺杂合金元素Ti能影响Nd2Fe14B/α-Fe交换耦合磁体整个晶化动力学过程,使α-Fe相的晶化激活能升高,抑制其从非晶相中析出.同时,降低1∶7亚稳相的晶化激活能,起到稳定亚稳相的作用.而且随着晶化温度的进一步提高, α-Fe和Nd2Fe14B两相由1∶7亚稳相分解产生,从而有效避免了α-Fe相的优先析出.显微组织观察表明,掺杂Ti的样品晶粒细小、分布均匀,平均晶粒尺寸在20 nm左右,没有特别大的α-Fe粒子出现.当Ti的掺杂量原子百分数为1.0%时,获得了最佳磁性能(BH)max=12 MG·Oe(1 G=10 相似文献
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以Zr-Al-Ni-Cu (Nb,Ti)大块非晶合金差示扫描量热分析实验为基础,利用Lasocka方程、Kissinger方程及Vogel-Fulcher-Tamman(VFT)方程对其玻璃转变的动力学性质从不同方面进行了研究.分析结果表明:玻璃转变表观激活能越小,则晶化转变激活能越大,表现出相反的难易程度,且玻璃转变表观激活能数值远较传统非晶要小,验证了大块非晶合金独特的结构特点及玻璃形成能力(GFA)强的原因.利用VFT方程对玻璃转变弛豫时间与升温速度的VFT曲线 进行了拟合,所算得的玻璃脆性参数m均在30左右,反映了Zr-Al-Ni-Cu (Nb,Ti)非晶合金强 的脆性属性.玻璃转变处Lasocka关系的B值、原子表观激活能及玻璃脆性参数均反映了相同的GFA大小趋势,从不同方面进一步揭示了非晶合金玻璃转变区间的动力学行为与GFA之 间的密切联系,可作为判断非晶合金GFA强弱的重要依据.
关键词:
玻璃转变
玻璃形成能力
表观激活能
玻璃脆性参数 相似文献
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通过在真空电弧熔炼炉内对合金铸锭进行反复熔炼处理,获得到了凝固组织不同的Zr65Al7.5Cu12.5Ni10Ag5合金铸锭.在相同的制备条件下,由凝固组织不同的合金铸锭通过吸铸法制备得到了薄片非晶合金.利用差示扫描量热法(DSC)对非晶合金的晶化动力学进行了分析.x射线衍射谱表明,在Zr65Al7.5Cu12.5Ni10Ag5非晶合金晶化过程中,二十面体准晶相(I相)作为初生相析出.Kissinger分析结果表明,合金铸锭的凝固组织细化,相对应的非晶合金发生晶化时,I相形成与分解的有效激活能都增大,说明非晶合金及析出的I相的热稳定性都提高.从结构的遗传性角度就合金铸锭凝固组织对相应非晶合金晶化过程中二十面体准晶相的形成动力学的影响进行了讨论.
关键词:
二十面体准晶相
晶化动力学
凝固组织 相似文献
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本文用中国第一台正电子湮没辐射一维角关联实验装置,测量了非晶锂离子导体B2O-0.7Li2O-0.7LiCl-xAl2O3(x=0.15;0.10;0.05)晶化过程中各条正电子湮没辐射的一维角关联曲线,并对归一化的电子动量分布进行了线形参数的计算,从其S参数同样能推测出该离子导体在晶化过程中缺陷浓度的变化。非晶离子导体B2O3-0.7Li2O-0.7LiCl-xAl2O3的实验结果表明,Al2O3组分不同,对非晶态样品在室温下一维角关联曲线的S参数亦无较大影响。完全晶化后,一维角关联曲线的S参数均有很大下降。在晶化过程最初期,无论Al2O3含量多少,S参数都明显略增;到晶化温度附近,仅对Al2O3含量较多的非晶,S参数反常增高。这些结果验证和补充了测正电子平均寿命得出的结论。由此初步证实了界面层有大量缺陷的物理图象。
关键词: 相似文献
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Amorphous Tb30Fe60Co10 films have been fabricated by magnetron sputtering. The dependences of the microstructure and magnetic properties of these films on the type and pressure of the gas in the sputtering chamber have been studied. The pressure of the Ar, Kr, and Xe gases used in the experiments is varied in the sputtering chamber from 0.01 to 4.00 Pa. It has been established that sputtering in the heavy gas (Kr) conducted within the pressure range covered does not permit fabricating TbFeCo films with the easy magnetization axis perpendicular to the film plane. With Xe used at pressures below 1.0 Pa, one observes in TbFeCo films an increase of the coercivity, with the hysteresis loop approaching rectangular shape. Sputtering and deposition in Ar at a pressure of ??0.67 Pa result in the formation of amorphous Tb30Fe60Co10 films with magnetic characteristics satisfying the requirements imposed upon information carriers intended to be employed in perpendicular recording. It has been demonstrated that, by magnetron sputtering in an Ar atmosphere performed at pressures below 1 Pa, one can produce amorphous Tb30Fe60Co10 films suitable for magneto-optical ultra-high-density information recording. 相似文献
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The influences of gallium substitution for terbium in Gd60Tb40 on the phase formation, Curie temperature and magnetic entropy change have been investigated. A series of Gd60Tb40−xGax with x=0, 1, 3 and 5 alloys were prepared by arc-melting method. The X-ray diffraction (XRD) analysis reveals that a small amount of Ga substitution for terbium in Gd60Tb40 can form the solid solution (Gd, Tb). The Curie temperature (Tc) increases from 270 K for Gd60Tb40 to 297 K for Gd60Tb37Ga3, while the maximum magnetic entropy changes ΔSM, max decreases from 5.15 J/K kg for Gd60Tb40 to 3.32 J/K kg for Gd60Tb37Ga3 with increasing the Ga content. 相似文献
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Amorphous Fe74Co10B16 (METGLAS 2605CO) has been studied in the temperature range of 77 K – 700 K by Mössbauer spectroscopy. Its crystallization temperature is found to be 665 ± 5 K and Curie temperature is estimated to be 760±10 K. The observed rapid decrease in reduced hyperfine fields can be explained well by Handrich's model for amorphous ferromagnets if one assumes a temperature dependent δ, a measure of fluctuations in the exchange interactions in such solids. 相似文献
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Magnetization measurements on amorphous Gd0.33Co0.67 films indicate that Tc is>30 per cent higher in the films than in the ordered compound, GdCo2, of the same composition. This reverses the trend observed in isostructural Tb0.33Fe0.67 and many other amorphous ferromagnets, where Tc is lower in the amorphous state. A qualitative explanation of the effect of structural disorder on magnetic properties of the Co and Fe compounds is given in terms of the consequences of charge transfer to the transition metal atoms. 相似文献
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J.J. Dolo H.C. Swart J.J. TerblansE. Coetsee O.M. NtwaeaborwaB.F. Dejene 《Physica B: Condensed Matter》2012,407(10):1586-1590
This paper presents the X-ray Photoelectron Spectroscopy (XPS) analysis for the undegraded and degraded Gd2O2S:Tb3+ thin film phosphor. The thin films were grown with the pulsed laser deposition (PLD) technique. XPS measurements were done on Gd2O2S:Tb3+ phosphor thin films before and after electron degradation. The XPS technique has proven the presence of Gd2O3 on the degraded and undegraded thin film spots. The presence of the SO2 bonding was also detected after degradation. This clearly indicates that surface reactions did occur during prolonged electron bombardment in an oxygen atmosphere. 相似文献
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Curie temperature, crystal structure and crystallization behavior of amorphous alloys with the stoichiometry Fe81−xNixZr7B12 (x=10–60) have been studied by X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and AC-magnetization (TMAG) measurements as functions of temperature. The thermal stability of long-range magnetic order, TC vs. Ni content in as-quenched amorphous alloys exhibits maximum at 352 °C for x=40. The primary crystallization has been detected during annealing at the first crystallization stage of all ribbons investigated. 相似文献
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用闪光蒸镀法在77K制备了NdxFe1-x(x=0.06-0.80)非晶薄膜,原位测定了其电阻随温度的变化。结果表明:在0.192和ρ(T)∝T。晶化不是在一个固定的温度,而是在一个温度区间发生。 相似文献
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The precipitous drop of crystallization temperature at the surface of amorphous Fe90Zr10 ribbon is confirmed by TMS and CEMS. The deficiency in Zr at the surface amorphous phase, caused by the absorption and the
diffusion of oxygen, is found to be responsible for it. The final crystalline products are assigned to α-Fe, Fe3Zr and Fe2Zr, whereas only α-Fe precipitates at the surfaces. Moreover, it is indicated that the crystallization behavior of the bulk
is influenced by the ambient gases during annealing and quite different between in vacuum and in air. 相似文献