Preliminary Mechanical Property Assessment of an Ultra SCS®/Ti-22A1-23Nb Composite

Abstract

The mechanical performance of an orthorhombic-based titanium aluminide matrix composite (OTMC) reinforced with Ultra SCS® silicon carbide continuous monofilament (i.e., Ultra SCS®/Ti-22Al-23Nb) was investigated. Tensile properties, creep resistance, isothermal fatigue, and thermomechanical fatigue were examined over the temperature range from 20 to 760°C, with the bulk of the testing conducted at the upper end of this range to more fully characterize the high-temperature performance of this new composite system. A comparison was made with two similar OTMCs consisting of SCS-6 and Trimarc 1® silicon carbide fiber reinforcement of a Ti-22Al-23Nb matrix. In general, the longitudinal properties benefited significantly as a result of the higher-strength Ultra SCS® fiber. Both the cyclic behavior, isothermal fatigue, and in-phase thermomechanical fatigue, as well as static properties, tension, and creep were improved. However, matrix-dominated performance, including out-of-phase thermomechanical fatigue and transverse properties, was similar or exhibited a slight debit in the Ultra SCS®/Ti-22Al-23 composite. The demonstrated improvement in longitudinal properties makes the Ultra SCS® composite system an excellent choice for rotating components in advanced gas turbine engine applications. However, improvements in transverse properties may still be required for those applications subjected to appreciable off-axis loads.