放电等离子烧结制备SiC/MoSi2复合材料的显微组织、烧结行为及力学性能

摘要

以Mo、Si和SiC粉末为原料,利用放电等离子烧结技术在不同温度下制备SiC/MoSi2复合材料,研究SiC/MoSi2复合材料的物相组成、显微组织和力学性能,并探讨其烧结行为.结果表明:SiC/MoSi2复合材料由MoSi2、SiC和少量的Mo4.8Si3C0.6组成,呈现细晶组织.在SiC/MoSi2复合材料的烧结过程中,存在固相烧结至液相烧结的演变.1600 ℃烧结的SiC/MoSi2复合材料表现出最好的力学性能,其维氏硬度、抗弯强度、断裂韧性分别为13.4 GPa、674 MPa 和 5.1 MPa?m1/2,比纯MoSi2分别提高了44%、171%和82%.第二相SiC作为硬质相可以承受外加应力,并阻碍裂纹的快速扩展,有助于复合材料力学性能的提高.%SiC/MoSi2composites were synthesized at different temperatures by spark plasma sintering using Mo, Si and SiC powders as raw materials. The phase composition, microstructure and mechanical properties of the as-prepared composites were investigated and the sintering behavior was also discussed. Results show that SiC/MoSi2composites are composed of MoSi2, SiC and trace amount of Mo4.8Si3C0.6phase and exhibit a fine-grain texture. During the synthesis process, there was an evolution from solid phase sintering to liquid phase sintering. When sintered at 1600 ℃, the SiC/MoSi2composites present the most favorable mechanical properties, the Vickers hardness, bending strength and fracture toughness are 13.4 GPa, 674 MPa and 5.1 MPa?m1/2, respectively, higher 44%, 171%, 82% than those of monolithic MoSi2. SiC can withstand the applied stress as hard phase and retard the rapid propagation of cracks as second phase, which are beneficial to the improved mechanical properties of SiC/MoSi2 composites.