磁场作用下Cr7C3硬质相生长机制

将纵向磁场引入到Fe5铁基合金粉末的等离子弧堆焊过程中,通过磁场的作用影响堆焊层中硬质相的形态及分布.利用金相显微镜和X射线衍射研究堆焊层中硬质相Cr₇C₃的显微组织和取向行为.结果表明,具有顺磁性的硬质相Cr₇C₃在外加磁场的作用下进行形核及长大的过程中有明显的取向现象,在磁场电流为3 A时,堆焊层中硬质相的分布形态最佳,以细小的"六边形"为主,可以显著提高堆焊层的影响和耐磨性;硬质相的取向机理主要是高温的旋转取向和低温的择优取向.

Formation mechanism of Cr7C3 hard phase under magnetic field

Longitudinal magnetic field was applied to the plasma arc surfacing of Fe-based alloy powder. The morphology and distribution of hard phase in surfacing deposit was changed by magnetic field. The microstructure and orientation of Cr₇C₃ hard phase in the Fe5 surfacing layer were tested by using the optical microscopy and X-ray diffraction. The results show that obvious orientation behavior of Cr₇C₃ hard phase with paramagnetism in the process of nucleation and growth under the effect of external magnetic field. When driving current of magnetic field is 3A,the distribution of Cr₇C₃ hard phase is optimum,which is fine and shown as "the hexagon" in the surfacing layer. The hardness and wear resistant are improved by the Cr₇C₃ hard phase. The formation mechanism of Cr₇C₃ hard phase is that revolution orientation during high temperature and preferential growing during low temperature.