Si_3N_(4(p))/SiC_((w))强韧化MoSi_2基复合材料的显微组织与力学性能

Microstructure and mechanical properties of MoSi_2-based composite strengthened and toughened by Si_3N_(4(p)) and SiC_((w))

采用热压工艺制备了不同Si3N4(p)和SiC(w)体积含量的MoSi2基复合材料,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、维氏硬度计、电子万能材料试验机等研究了复合材料的显微组织、硬度、断裂韧度和抗弯强度,并对其强韧化机理进行了初步探讨。结果表明,复合材料结构致密,强化相与MoSi2之间没有新相生成,力学性能较纯MoSi2得到大幅度提高,其中MoSi2-20%Si3N4(p)-20%SiC(w)复合材料具有最好的抗弯强度和断裂韧度,分别为427MPa和10.4MPa.m1/2。复合材料的强化机制为细晶强化和弥散强化,韧化机制为细晶韧化和裂纹偏转与分支韧化。

MoSi2 composites with different Si3N4（p）and SiC（w）volume contents were prepared by hot pressing process.The structure,morphology,hardness,fracture toughness,bending strength,strengthening and toughening mechanism of the MoSi2-Si3N4（p）/SiC（w）composites were investigated by means of X-ray diffraction（XRD）,Scanning electron microscope（SEM）,Vichers hardness tester,and electronic universal material tester.It is shown that mechanical properties of the prepared composites are much higher than that of MoSi2,there is no new phase generated between strengthening phase and MoSi2.SiC whiskers and Si3N4 particles have good strengthening and toughening effect on MoSi2,MoSi2-20vol% Si3N4（p）-20vol%SiC（w）composite has the highest bending strength and room fracture toughness,which is 427 MPa and 10.4 MPa·m^1/2,respectively.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 toughening.