Preliminary mechanical property assessment of an Ultra SCS (R)/Ti-22A1-23Nb composite

The mechanical performance of an orthorhombic-based titanium aluminide matr ix composite (OTMC) reinforced with Ultra SCS(R) silicon carbide continuous monofilament (i.e., Ultra SCS(R)/Ti-22Al-23Nb) was investigated. Tensile p roperties, creep resistance, isothermal fatigue, and thermomechanical fatig ue were examined over the temperature range from 20 to 760 degrees C, with the bulk of the testing conducted at the upper end of this range to more fu lly characterize the high-temperature performance of this new composite sys tem. A comparison was made with two similar OTMCs consisting of SCS-6 and T rimarc 1(R) silicon carbide fiber reinforcement of a Ti-22Al-23Nb matrix. I n general, the longitudinal properties benefited significantly as a result of the higher-strength Ultra SCS(R) fiber. Both the cyclic behavior, isothe rmal fatigue, and in-phase thermomechanical fatigue, as well as static prop erties, tension, and creep were improved. However, matrix-dominated perform ance, including out-of-phase thermomechanical fatigue and transverse proper ties, was similar or exhibited a slight debit in the Ultra SCS(R)/Ti-22Al-2 3 composite. The demonstrated improvement in longitudinal properties makes the Ultra SCS(R) composite system an excellent choice for rotating componen ts in advanced gas turbine engine applications. However, improvements in tr ansverse properties may still be required for those applications subjected to appreciable off-axis loads.