| Reaction Hot Pressed Silicides and Silicide Matrix
Composites : Processing, Microstructure and Properties |
R. MrrRA, N. EswARA PR.t..SAD ANDY. R. MAHAJAN
Pages: 71-78
DOI : 10.1080/0371750X.1997.10804797 |
| Abstract |
| Molybdenum and titanium silicides (MoSi2 and Ti5Si 3) and
their composites have been processed by reaction hot pressing
of stoichiometric ratios of mixtures of powders of Mo/Si and
TiHz!Si without and with reinforcement powders, respectively
at 1500 C in vacuum. MoSi2 and Ti5Si3 form in situ by diffusion
of Si atoms (in liquid state) under external pressure into the Mo
and Ti lattice, respectively, followed by chemical reaction. The
pmcessing parameters and particle sizes of the raw materials
affect the density, microstructure, grain size and other properties
of the composite. In the MoSi2/20 vol% SiC composite,
most of the MoSi 2/SiC interfaces are atomically abrupt.
However, a few interfaces contain a layer of amorphous Si02
5-8 nm thick. Fracture toughness and flexural strengths increase
with the decrease in grain sizes. Ti5Si3 and Ti5Si3/20
vol% TiC composite having similar grain size show a higher
hardness and fracture toughness in the composite. |
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