A low CTE metal-ceramic composite material featuring carbon fibers
reinforcing a matrix featuring silicon metal or silicon alloy. The fibers
have a low coefficient of thermal expansion (CTE) in the axial direction,
and preferably negative. The principles of making Si/SiC composites can
be adapted to produce the instant Si matrix composites. The CTE of the
composite body depends not only upon the relative CTE's of the fibers and
matrix, and their relative amounts (e.g., loadings), but also upon the
relative elastic moduli of the fibers and matrix. Thus, Si/SiC matrices
produced by a reaction-bonding process inherently possess low CTE, but
the instant inventors prefer to make such composites having relatively
large fractions of unreacted silicon, thereby driving composite CTE lower
still. Here, the carbon fibers are protected from reaction with the
silicon infiltrant with one or more materials disposed between the fibers
and the infiltrant. Providing at least a degree of toughness or impact
resistance can also be realized in these composites. Laminates produce
Isotropic or quasi-isotropic properties in the composite body can be
realized by, for example, providing the fibers in the form of cross-plied
laminates featuring the fibers in parallel or woven arrays.