SiCウイスカー強化MoSi_2複合材料の機械的性質

概要

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Molybdenum disilicide (MoSi_2) is considered as a candidate material for high temperature structural applications, particularly in oxidizing environments. In the present study, SiC-whisker reinforcement has been applied to improve the mechanical properties such as fracture strength and fracture resistance at room temperature as well as creep resistance at elevated temperature. Almost dense SiC-whisker-reinforced MoSi_2 composites containing up to 20 vol% whisker were fabricated by hot-pressing at 1750℃. Due to the well-dispersed composite structure with fine grained matrix, the composites showed much higher bending strength than unreinforced materials; the average 4-point bending strength increased from 350 MPa for MoSi_2 to 870 MPa for MoSi_2-20%SiC_W. The fracture resistance also considerably improved by the SiC-whisker reinforcement. The composites exhibited increasing R-curve behavior and the plateau values were about 23-34% higher compared to that of the unreinforced materials. Crack bridging was found to be mainly responsible for the toughening contribution. Creep resistance was remarkably increased by the suppression effect of SiC-whisker on the grain boundary sliding, which was confirmed to be an important deformation mechanism in MoSi_2 polycrystals.
社団法人日本セラミックス協会の論文
1997-03-01