The feasibility of fabricating intermetallic NiAl-sapphire fiber composites by casting and zone directional solidification
has been examined. The fiber-matrix interfacial shear strengths measured using a fiber push-out technique in both cast and
directionally solidified composites are greater than the strengths reported for composites fabricated by powder cloth process
using organic binders. Microscopic examination of fibers extracted from cast, directionally solidified (DS), and thermally
cycled composites, and the high values of interfacial shear strengths suggest that the fiber-matrix interface does not degrade
due to casting and directional solidification. Sapphire fibers do not pin grain boundaries during directional solidification,
suggesting that this technique can be used to fabricate sapphire fiber reinforced NiAl composites with single crystal matrices.