Microstructure and phase transformation behavior of Mo–MoSi2 gradient material

• DOI: 10.1007/s12598-014-0273-8
• Publication Date: 2014-08-01T21:36:09Z
• Authors: Ying-Yi Zhang; Yun-Gang Li; Yong-Hong Qi; Xue-Feng Shi
• Keywords: Molybdenum disilicide

Mo–MoSi2 gradient coating on Mo substrate was prepared by siliconizing process, using the polysilicon as silicon atoms. The gradient layer was analyzed by the experimental results, theoretical analysis, and thermodynamic calculation. The silicon, molybdenum content of gradient coating shows a gradual change regulation. The reaction between silicon and molybdenum is most likely to generate Mo5Si3, then MoSi2, finally Mo3Si, but when the silicon content is excessive, the Mo5Si3 and Mo3Si will react with silicon and generate MoSi2. The gradient layer is mainly constituted by Si and MoSi2, only about 1/10 gradient layer is constituted by Mo5Si3 and Mo3Si, and the stable existences of Mo5Si3 and Mo3Si are mainly determined by the silicon content. Along the Mo substrate to the surface of the coating, the phase composition of gradient coating changes as follows: Mo → transition layer, Mo (main phase) + Mo3Si + Mo5Si3 → intermediate layer, and MoSi2 (main phase) + Mo5Si3 + Si → surface layer MoSi2 (main phase) + Si, and the experimental temperature has no effect on phase composition of gradient coating.