AAWSAP DIRD, Materials for Advanced Aerospace Platforms, January 2010

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Figure 4 shows an example of a TI matrix composite (TMC) cross section.
Figure 4. Cross-Section Micrograph of a Ti Matrix Composite. Small, dark centers
of fibers are C monofilament substrates for deposition of SiC (light micrograph).
Material system: Matrix alloy - Ti-6242; Fiber - SiC about 5.6-mil-diameter SCS-6
Table 2 shows that the strength and stiffness properties of TMCs can exceed those of
the Ti matrix (or other a.+13 Ti alloys) by more than a factor of two with no increase in
density. So why are TMCs not in widespread use? The foremost reason is cost. Another
reason is the availability of SiC fiber for TMCs.
•
During the 1990s, when the U.S. government (mainly DoD) was interested in and
provided development money for TMC R&D, the most attractive reinforcing fiber was
SCS-6™, which was produced exclusively by Textron Specialty Materials (TSM) in
Lowell, MA.
•
Unfortunately (at least in hindsight), TSM made a business decision not to sell fiber
and to instead forward-integrate and sell TMC components or finished TMC mill
products. This decision stemmed in part from TSM's negative business experience
with development of B-based fiber (Boro-SiC™) for first-generation TMCs.
•
Prior to making this business decision, TSM did not develop sufficient TMC­
manufacturing expertise to properly position itself as a producer of TMC products
with consistent properties.
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