The Reactivity of Ti2AlC and Ti3SiC2 with SiC Fibers and Powders up to Temperatures of 1550 degrees C
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abstract
The reactivities of commercially available Ti 2 AlC or Ti 3 SiC 2 powders with uncoated SiC fibers or SiC powders were evaluated in this paper. When Ti 2 AlC-SiC samples were hot pressed or hot isostatically pressed at temperatures up to 1500C, fully dense composites were obtained. The latter were characterized by X-ray diffraction and electron-dispersive spectroscopy in a scanning and transmission electron microscope. Differential thermal analysis up to 1550C was also carried out. In all cases, SiC reacted with the Ti 2 AlC powder resulting in the formation of Ti 3 (Al 1-x Si x )C 2 TiC and Al 1+x Ti 1-x , where x ranges from 0 to 1. In the limit x=1, pure Al forms. Conversely, Ti 3 SiC 2 samples, reinforced with uncoated SiC fibers or powders, can be hot pressed in vacuum at temperatures as high as 1500C to produce fully dense composites with no apparent reaction between the matrix and fibers. Based on these results, Ti 3 SiC 2 can, but Ti 2 AlC cannot, be reinforced with SiC. Such reinforcements will be needed if the MAX phases are to be used as structural materials at very high temperatures. 2011 The American Ceramic Society.
