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用X射线衍射方法对液相烧结的RCo_5型永磁体内的金属相结构进行了分析,配合着也观测了磁性,烧结体无例外地有一个约0.3毫米厚的表皮层;故须把烧结体的表皮层和核心部分分离,对它们分别进行观测,磁性测量则只是对核心部分作的,结果表明,表皮层与核心相比,它的结构较为复杂;但仅就成分讲,则它的R含量较高,Co含量较低,具有最大矫顽力的烧结体核心只显示了一个金属相,即具有CaZn_5型结构的RCo_5型金属间化合物,X射线衍射未察觉有其它金属相(R_2Co_7或R_2Co_(17))的存在;这情况出现在63％(重量)的总Co含量附近,也对烧结前的混合粉中的“液相”含量作了变化,使烧结体的总Co含量偏离此值,这些不同Co含量的烧结体核心中一般地有第二个金属相的出现,随着这第二相(不论是R_2Co_7或R_2Co_(17))的出现,核心的永磁特性就降低,根据上述结果,试提出以液相转变为主的烧结模型,磁性最佳的烧结体核心本质上是单相的RCo_5型结构,这一结果是与Strnat等提出的以R_2Co_7外延层的存在为基础的“磁壳钉扎模型”相矛盾的。
The structure of the metal phase in the liquid phase sintered RCo_5 permanent magnet was analyzed by X-ray diffraction. The magnetic phase was also observed with the exception of a 0.3 mm thick skin layer of the sintered body. Therefore, the sintered body Of the epidermis and the core part of the separation, respectively, to observe them, the magnetic measurement is only made of the core part of the results show that the epidermis compared with the core, its structure is more complex; but only speaking composition, then its R In the sintered core with the highest coercivity, only one metal phase, ie, the RCo5 intermetallic compound with CaZn5 type structure, is found in the core with the highest coercivity. Other metal phases (R_2Co_7 or R_2Co_7 (17)) occurred in the vicinity of 63% by weight of the total Co content and the “liquid phase” content in the mixed powder before sintering was also changed so that the total Co content of the sintered body deviated from this value , The occurrence of the second metal phase in the core of these sintered bodies with different contents of Co generally decreases with the appearance of this second phase (whether R_2Co_7 or R_2Co_ (17)). According to the above As a result, it is proposed to sinter mainly liquid phase transition The model, the magnetically best sintered core, is essentially a single-phase RCo_5-type structure that is in contradiction with the “magnet shell pinning model” proposed by Strnat et al. That is based on the presence of an R_2Co_7 epitaxial layer.