THERMAL CYCLING RESPONSE AND OXIDATION BEHAVIOR OF AL2O3/NIAL COMPOSITES WITH INTERFACIAL MO COATING

Thermal cycling response and oxidation behavior of Al2O3/NiAl composites with interfacial Mo coating were studied and results compared with that for weakly bonded composites without any interfacial coating. Thermal cycling of composites with interfacial Mo coating from room temperature to 1300 K in an inert atmosphere resulted in interfacial debonding along the Mo-Al2O3 interface, with the extent of debonding increasing with number of thermal cycles. Both isothermal and cyclic oxidation of composites with interfacial Mo coating at 1373 K resulted in a thick, dense Al2O3 scale along the fiber-matrix interface near the fiber ends. The depth of interfacial oxide penetration was confined to a short distance (about 100 mu m) from the fiber ends, with the rest of the composite intact. This is in contrast to the oxidation behavior of weakly bonded composites without any interfacial coating, in which oxidation along the fiber-matrix interface occurred throughout the composite, not just near the fiber ends.