原位反应热压SiCp/MoSi2复合材料的组织与性能

以Mo粉、Si粉和C粉为原料,采用原位反应热压一次复合工艺制备不同含量SiC颗粒增强的SiCp/MoSi2试样,并研究其室温抗弯强度、断裂韧性、相对密度以及显微组织。结果表明,原位反应热压一次复合工艺制备的SiCp/MoSi2复合材料的强韧性比纯MoSi2有了大幅度的提高,当SiC含量为40vol%时,SiCp/MoSi2复合材料的抗弯强度达到最大,为475.2MPa,当SiC含量为50vol%时,复合材料的断裂韧性达到最大,为5.45MPa.m1/2。原位形成的SiC使MoSi2基体晶粒得到明显细化,并减少和消除了脆性的SiO2玻璃相。SiCp/MoSi2复合材料强韧性的提高主要是由于晶粒细化、SiC颗粒弥散强化以及脆性SiO2玻璃相的减少和消除。

Microstructure and mechanical properties of SiCp/MoSi2 composites prepared by in situ synthesis and hot-pressing

SiC_p/MoSi_2 composites with different volume fraction of SiC were prepared by the technique of in situ synthesizing and hot-pressing the pure powder of Mo,Si and C.The bend strength,fracture toughness and relative density of the composites were measured and the microstructure was observed.It is found that the strength and toughness of the composites are increased compared with those of mono MoSi_2 material.The maximum bend strength of 475.2MPa in the composite with 40vol%SiC and the maximum fracture toughness of 5.45 MPam~(1/2) in the composite with 50vol%SiC are obtained.It is observed that the in situ formed SiC particles refine the MoSi_2 grains and eliminate the brittle SiO_2 glass phase.The increase of the strength and toughness of SiC_p/MoSi_2 composites is mainly attributed to the refinement of MoSi_2 grains,dispersion strengthening of the SiC particles and elimination of the brittle SiO_2 glass phase.