The influence of the grain boundary phase on the mechanical properties of Si3N4-MOSi2 composites

被引：21
作者：
Guo, Zhiquan
Parlinska-Wojtan, Magdalena
Blugan, Gurdial
Graule, Thomas
Reece, Mike J.
Kuebler, Jakob
机构：
[1] EMPA, Lab High Performance Ceram, Swiss Fed Labs Mat Testing & Res, CH-8600 Dubendorf, Switzerland
[2] EMPA, Lab Nanoscale Mat Sci, Swiss Fed Labs Mat Testing & Res, CH-8600 Dubendorf, Switzerland
[3] Queen Mary Univ London, London E2 4NS, England
来源：
ACTA MATERIALIA | 2007年 / 55卷 / 08期
关键词：
TEM; grain boundaries; ceramic matrix composites (CMC); mechanical properties;
D O I：
10.1016/j.actamat.2006.12.026
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The microstructure and mechanical properties Of Si3N4-MOSi2 composites doped with two different sintering additive systems, Y2O3-Al2O3 and Lu2O3, were investigated. It was found that the composite doped with Y2O3-Al2O3 had an amorphous grain boundary phase, while the grain boundary phase of the Lu2O3-doped composites was completely crystallized. The Si3N4-MOSi2 composite containing Lu2O3 had higher elastic modulus and better creep resistance at elevated temperatures (> 1000 degrees C) than the composite doped with Y2O3-Al2O3. This is attributed to the crystallization and higher softening temperature of the Lu2O3-doped grain boundary phase compared with that doped with Y2O3-Al2O3. However, the toughness and strength were not influenced significantly by the grain boundary phase. The inclusion Of MOSi2 particles in Si3N4 can improve their fracture toughness through residual stresses induced by the coefficient of thermal expansion mismatch of Si3N4 and MoSi2. The strength decreased significantly at temperatures over 1000 degrees C due to the brittleductile transition of the MOSi2 phase. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
引用
收藏
页码：2875 / 2884
页数：10
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