Temperature dependence of tensile mechanical properties in SiC fiber-reinforced Ti matrix composite

Abstract

Temperature dependence of longitudinal Young's modulus, tensile strength, and interfacial shear stress in SiC(SCS-6) fiber-reinforced commercially pure Ti matrix composites have been examined experimentally in the temperature range from room temperature to 873 K. Young's modulus and tensile strength of the composite was discussed in relation to the interfacial shear stress transfer mechanism. Young's modulus was independent of interfacial shear stress, however, the tensile strength depended strongly on the interfacial shear stress. With increasing test temperature, the interfacial shear stress decreased, a behavior which originated from an insufficient stress transfer between fiber and matrix due to decrease of shear yield stress of the matrix. The tensile strength of the composite depended on the potential of shear stress transfer at the interface, and the temperature dependence of the tensile strength was quantitatively explained by the proposed “in-direct stress transfer model”. The model suggests when the length of the composite in the longitudinal direction was sufficiently long, R f σ fu /σ my L g ≈ 0 where R f is the radius of fiber, σ fu is the mean tensile strength of fiber, σ my is the yield stress of matrix, L g is the length of composite, the tensile strength of the composite approaches the rule of mixture prediction for continuous fiber-reinforced metals even at elevated temperatures. This result also indicated that the tensile strength of the composite depended strongly on the gage length of the composite L g, and this tendency increased with decrease in the shear yeild stress of the matrix.