Si3N4(p)/SiC(w)协同复合MoSi2材料的强韧化及机理研究

采用X射线衍射(XRD)、扫描电子显微镜(SEM)、维氏硬度计、电子万能材料试验机研究MoSi_2-Si_3N_(4(p))/SiC_(w)复合材料的结构、形貌、硬度、断裂韧性,并对SiC晶须和Si_3N_4颗粒复合强韧化MoSi_2的机理进行了探讨.结果表明,SiC晶须和Si_3N_4颗粒对MoSi_2具有协同强韧化作用,MoSi_2-20%Si_3N_(4(p))-20%SiC_(w)(体积分数,下同)复合材料的抗弯强度达427 MPa,室温断裂韧性达到10.4 MPa·m~(1/2),均高于单一强韧化剂的强韧化效果.MoSi_2-20%Si_3N_(4(p))-20%SiC_(w)复合材料的强化机理为细晶强化和弥散强化;韧化机制为细晶韧化、裂纹偏转与分支和微桥接韧化.

Strengthening and Toughening Effect and Its Mechanism for

The structure, morphology, hardness, breaking toughness, strengthening and toughening mechanism of MoSi2-Si3N4(p)/SiC(w) composites were investigated by means of XRD, SEM, Vichers hardness tester and electrical omnipotence material tester in this paper. It is shown that the SiC whiskers and Si3N4 particles have the coordinated strengthening and toughening effect on MoSi2, the bending strength and room temperature fracture toughness of MoSi2-20 vol% Si3N4(p)-20 vol%SiC(w) composite are 427 MPa and 10.4 MPa·m1/2, respectively, which is higher than that of MoSi2 strengthened and toughened by SiC whiskers or Si3N4 particles. The strengthening mechanism of MoSi2-Si3N4(p)/SiC(w) composites are the fine grains and dispersion strengthening, and the toughening mechanism are the fine grain toughening and the crack deflection and the micro bridge join toughening.