原位SiC颗粒增强MoSi_2基复合材料的显微组织和力学性能

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF IN SITU SiC PARTICULATES REINFORCED MoSi_2 MATRIX COMPOSITE

本文研究了原位 ＳｉＣ颗粒增强 ＭｏＳｉ２基复合材料的组织结构和力学性能。结果表明：复合材料的组织为ｔ－ＭｏＳｉ２基体上均匀分布 β－ＳｉＣ等轴颗粒，数量很少的球形小孔隙主要分布在 ＳｉＣ颗粒内， ＳｉＣ颗粒尺寸为 ２－５ μｍ．复合材料界面为直接的原子结合，无非晶层存在．复合材料的室温维氏硬度、断裂韧性、抗压强度及高温流变应力明显高于单一ＭｏＳｉ２，随着ＳｉＣ体积分数的增加，维氏硬度、断裂韧性及高温流变应力提高，而抗压强度先增加后减少． ＳｉＣ体积分数从 １０％增加到 ４５％，ＫＩＣ从 ４．３４提高到 ５．７１ ＭＰａ·ｍ１／２；与单一 ＭｏＳｉ２相比提高了 ２５％－４６％； １４００℃时，σ０．２从 ２０％ＳｉＣ的 ２３０提高到 ４５％ＳｉＣ的 ２８５ ＭＰａ，比单一 ＭｏＳｉ２提高了 ９８％－１４６％．

Microstructure and mechanical properties of in situ SiC particulates reinforced MoSi2 matrix composite were investigated in this work. The results show that the microstructure of the composite consists of the beta -SiC equiaxed particulates with size of 2-5 mum, uniformly distributed in the MoSi2 matrix. A small amount of sphere pore is located within the SiC particulates. The MoSi2-SiC interface is atomically abrupt, free from amorphous phase (SiO2). The hardness, fracture toughness(K-IC), compressive strength at room temperature and flow stress at high temperature for the composite are significantly higher than those for the monolithic MoSi2. As volume percent of SiC increases, the hardness, toughness and flow stress increase, while the compressive strength at first increases and then decreases. As volume percent of SiC increases from 10 to 45, K-IC increases from 4.34 to 5.71 MPa .m(1/2), by a factor of 25%-46% than the monolithic MoSi2; At 1400 degreesC, sigma (0.2) increases from 230 to 285 MPa when SiC volume fraction increases from 20% to 45%, which corresponds to an increasing factor of 98%-146% than MoSi2.