Phase relations and extrinsic magnetic properties of Sm–(Fe,Co)–Ti–(Ga)-based alloys for ThMn12-type permanent magnets
Phase relations and extrinsic magnetic properties of Sm–(Fe,Co)–Ti–(Ga)-based alloys for ThMn12-type permanent magnets
复制标题
ThMn12型永磁体用Sm–(Fe,Co)–Ti–(Ga)基合金的相关系和外磁性能
DOI：
10.1016/j.jmmm.2021.167866
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发表时间：
2021
影响因子：
2.7
通讯作者：
K. Hono
中科院分区：
文献类型：
--
作者：
A. Srinithi;H. Sepehri;Xin Tang;P. Tozman;J. Li;J. Zhang;S. Kobayashi;T. Ohkubo;T. Nakamura;K. Hono
实现ThMn_（12）型Sm（Fe，Co，Ti）_（12）化合物的非铁磁晶间相是发展高矫顽力磁体的前提。在本工作中，我们证明了Ga的加入到Sm-（Fe，Co）-Ti系统中的结果形成非铁磁性的Sm-Ga富晶间相，具有良好的润湿性Sm（Fe，Co，Ti）12晶粒。在Sm-（Fe，Co）-Ti系中，当合金成分变化到富Sm区Sm 1 +w（Fe0.8Co0.2）11 Ti（w= 0 ~ 0.7）时，铸态合金中除了ThMn 12型主相外，还形成了软铁磁性的C15型Sm（Fe，Co）2晶间相和TbCu 7型Sm（Fe，Co，Ti）7相。结果表明，Ga的引入可以阻止二次软铁磁相的形成，过量的Sm和Ga在Sm（Fe，Co，Ti）12晶粒上形成非铁磁的Ba 5Si 3型Sm 5Ga 3和TII型SmGa晶间相，并具有良好的润湿性。采用快淬工艺制备了Sm（Fe，Co，Ti）1-2晶粒，晶粒尺寸为1-2 μm，被富Sm-Ga晶界相隔离，最大矫顽力为0.5T。根据详细的微观结构表征，弱链接到这种新颖的微观结构的良好隔离和细Sm（Fe，Co，Ti）12-基晶粒的结晶性是在界面处的缺陷的存在下，这可能会导致局部降低磁晶各向异性。
Realizing a non-ferromagnetic intergranular phase for the ThMn12-type Sm(Fe,Co,Ti)12compound is a prerequisite for developing high coercive magnets. In this work, we demonstrate that the addition of Ga into the Sm-(Fe,Co)-Ti system results in the formation of non-ferromagnetic Sm–Ga-rich intergranular phases with good wettability on Sm(Fe,Co,Ti)12grains. In the Sm-(Fe,Co)-Ti system, when the alloy composition was varied to the Sm-rich region as Sm1+w(Fe0.8Co0.2)11Ti (w= 0–0.7), soft ferromagnetic C15-type Sm(Fe,Co)2intergranular phase and TbCu7-type Sm(Fe,Co,Ti)~7phase formed along with the ThMn12-type main phase in the as-cast alloy. We demonstrated that by introducing Ga, the formation of these secondary soft ferromagnetic phases can be hindered as the excess Sm and Ga formed non-ferromagnetic Ba5Si3-type Sm5Ga3and TII-type SmGa intergranular phases with an excellent wettability on Sm(Fe,Co,Ti)12grains. Fine Sm(Fe,Co,Ti)12grains of 1–2 µm, well isolated by the Sm–Ga-rich intergranular phase, were realized by melt-spinning the Ga-doped alloy and the maximum coercivity obtained was 0.5 T. According to the detailed microstructure characterizations, the weak-links to the coercivity of this novel microstructure of well-isolated and fine Sm(Fe,Co,Ti)12-based grains is the presence of defects at the interfaces which could lead to a locally reduced magneto-crystalline anisotropy.