富硼相及其在Nd-Fe-B合金中的行为

The Boron-Rich Phase and Its Behaviour in Nd-Fe-B Magnet

    摘要
  • 摘要: 本文利用1000kV超高压电镜、穆斯堡尔谱仪、X射线衍射仪和磁测量仪等对Nd-Fe-B永磁合金中的富硼相进行了研究。结果表明:富硼相以1个孤立的相存在于Nd-Fe-B永磁合金中,它一般位于基体相Nd2Fe14B的三角晶界处,占据的体积份数为4.6%,富硼相中有高密度的缺陷存在,这些缺陷的方向垂直于\vec C轴。
    富硼相的化学式可以写为Nd1+εFe4B4(s≈0.1),该化合物由2套亚结构,即Fe-B亚结构和Nd亚结构相互套穿而成。2个亚结构均具有四方对称,在四方基面上的晶格常数相同,但沿\vec C方向却有不同的周期,所以富硼相可能为一维的成分变化型无公度结构。在室温下富硼相呈顺磁性,能够在磁体中钉扎畴壁而提高矫顽力,富硼相的显微结构和温度有关,由矫顽力对温度的依赖关系和电镜观察表明富硼相对畴壁的钉扎可能属于强钉扎。

     

    Abstract: The boron-rich phase in Nd-Fe-B magnet was studied by means of HVEM, Mossbauer spectroscopy, X-ray diffraction and magnetic measurements. The chemical formula of the boron-rich phase can be represented by Nd1+εFe4B4. It is composed of two interpenetrating substructures, both have tetragonal symmetry. Since two substructures have different periods in \vec C direction, the boron-rich phase may belong to the compositional incommensurate structure in one dimension. It is paramagnetic at room temperature and may behave as the pinning sites in the magnet. The observation results by HVEM of micrOstructure of Nd-Fe-B alloy at different temperature are also given. The coercivity mechanism is discussed coupling with the reported results.

     

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