磁场烧结硬质合金强化机理研究

将磁场烧结新工艺以及常规烧结工艺制备的两类WC-Co硬质合金样品,进行电解腐蚀后,采用X射线衍射技术,对其粘结相中的C,W含量以及马氏体相对含量进行了测定。发现:磁场烧结合金粘结相中溶入的C,W原子较少,而其粘结相内马氏体含量较高。分析认为:主要由于均匀磁场的存在,使高温顺磁Co原子间交换耦合加强,妨碍了C,W原子与Co的结合,从而,溶解度降低。其效果是,改善了粘结相的润湿性和流动性,促进合金致密化,降低WC间邻接度;另一方面,使WC颗粒保持较锐利的棱角。这是磁场烧结提高合金性能的重要原因。

RESEARCH INTO THE STRENGTHENING MECHANISM OF SINTERING HARD ALLOYS IN THE MAGNETIC FIELD

Both samples sintered in the magnetic field and samples sintered by conventional technology were corroded with the aid of the electrolysis. By both X-ray diffraction technique and the calculations on the basis of the specific relationship, cobalt and tungsten content and the volume fraction of martensite of thier binder phases were determined. It is found that the binder phases of the hard alloys sintered in the magnetic field contain less carbon and tungsten and more martensite than those sintered by conventional technology. It is believed that the magnetic field has strengthened the coupler among the cobalt atoms, impeded the combination of carbon and tungsten with cobalt atoms, and hence lowered their solubility in the binder phases. As a result, the wettability and fluidity of the binder phases are improved, the density of alloys is increased, the contiguity among the WC grains is decreased. These are the important reasons why the sintering in the magnetic field can remarkably heighten the strength of alloys.