二硅化钼基材料的晶界腐蚀方法探讨

Methodological probe into grain boundary etching of molybdenum disilicide based materials

通过采用所选的化学腐蚀剂的系列实验,对不同工艺制备的MoSi2基材料进行了晶界腐蚀实验,利用XJG-04型金相显微镜和扫描电子显微镜(SEM),研究了MoSi2基材料腐蚀后的显微组织,并对其腐蚀结果进行了探讨.研究结果发现,用热压烧结法制备的致密度较高的MoSi2基材料具有晶间腐蚀敏感性,可用(HF+HNO3+H2O)作为其晶界腐蚀剂显示晶粒大小;MoSi2基材料的微观结构对晶界腐蚀有很大的影响,孔隙等缺陷越少,越有利于晶界的腐蚀,当孔隙率较高时其腐蚀模式主要为缝隙腐蚀,不宜用腐蚀的方式显示晶粒大小.

By means of serial experiments of chemical corrodents, grain boundary etching of MoSi2-based materials prepared with different processings was conducted. Microstructure of corrosion of these materials was investigated by using metallographical microscope XJG-04 and scanning electron microscope（SEM）, and the result of corrosion was discussed, also. It was found that there is sensibility of intergranular corrosion in the MoSi2-based materials with finer texture, which was prepared by means of hot-pressed sintering process, and the solution of HF＋HNO3＋H2O can be used as grain boundary corrosive to show the size of grain. The microstructure of MoSi2-based materials has great influence on grain boundary corrosion, and the fewer the defects such as porosity,the more beneficial to grain boundary corrosion would be. When the porosity is higher, the corrosion behaves mainly as a sort of crevice corrosion,so that the corrosion is not a suitable way to show the size of grain.