Transactions of the INDIAN CERAMIC SOCIETY Vol. 60 2001
Effect of Processing Methods on Purity, Structure of
Interfaces and High Temperature Strength of
MoSi2 and MoSi2-SiC Composites
R Mitra and A. Venugopal Rao
Pages : 12-20
DOI : 10.1080/0371750X.2001.10799954
Abstract
The effect of processing methods on the purity and structure of
MoSi2 grain boundaries and MoSi2-SiC interfaces and their
elevated temperature mechanical properties have been investigated.
The processing techniques involve formation of MoSi2 by
in-situ reaction, hot pressing of elemental Mo and Si powders
and conventional hot pressing of commercial grade Starck MoSi2
powders. The Si02 contents of the hot pressed products have
been found to be sharply different, depending on the processing
methods and the composition of the raw materials used.
Transmission electron microscopy (TEM) examination has shown
that reaction-hot-pressed MoSi2 based materials possess
atomically abrupt grain boundaries (matrix) and interfaces
(MoSi2-SiC composites), which are free of amorphous layers,
while Starck MoSi2 contains globular Si02 particles. Compression
tests in the range of 1100'-1300°C have shown that the
reaction-hot-pressed MoSi2 and MoSi2-SiC composite have
superior properties. The mechanisms of high temperature
deformation and serrated flow behaviour have been investigated
using TEM of deformed specimens.