第二相对MoSi_2基复合材料组织与性能的影响

The influence of second phase on the microstructure and mechanical properties of MoSi_2 matrix composites

用放电等离子烧结法(SPS)制备了不同增强相的MoSi_2基复合材料,系统研究了第二相对MoSi_2基复合材料组织与性能的影响,探讨了MoSi_2基复合材料的断裂方式及增韧机制。结果表明:第二相颗粒的加入均能不同程度地提高MoSi_2的强韧性;ZrO_2对提高断裂韧性最有效,其中20%ZrO_2/MoSi_2材料达到6.8 Mpam^(1/2),比纯MoSi_2提高了95.4%,表现为微裂纹增韧和弥散强化;β-Si_3N_4对提高显微硬度、抗压强度最有效,其中20%β-Si_3N_4/MoSi_2分别达到16.01Gpa与2260Mpa,比纯MoSi_2提高了31.7%与119.4%,表现为细晶强化;同时加入ZrO_2与β-Si_3N_4能起到相变增韧和细晶强化的协同作用,表现出最佳的强韧性能,其中,10%ZrO_2/20%β-Si_3N_4/MoSi_2的维氏硬度、抗压强度、断裂韧性分别比MoSi_2提高了24.7%、104.3%、90%。

MoSi2 matrix composites with different strengthen phases were prepared by the spark plasma sintering （SPS） technique, the influence of second phase on the microstructure and mechanical properties of MoSi2 matrix composites were systematically studied, and the fracture mechanics and toughening mechanism of MoSi2 matrix composites also be investigated. The results show that compared with MoSi2 monomer, the hardness, compression strength, fracture toughness of 10%ZRO2/20% β-Si3N4/MoSi2 composite increase by 24.7%,104.3%,90% respectively; Furthermore, dispersion strengthening and microcrack toughening are the major toughening mechanism of ZrO2/MoSi2 composite, fine-grained strengthening is the toughening mechanism ofβ-Si3N4/MoSi2 composite, and the ZrO2/β-Si3NflMoSi2 composite is the effect of transformation toughening and fine-grained strengthening.