TEMPERATURE-DEPENDENCE OF TENSILE MECHANICAL-PROPERTIES IN SIC FIBER-REINFORCED TI MATRIX COMPOSITE

Temperature dependence of longitudinal Young's modulus, tensile streng th, and interfacial shear stress in SiC(SCS-6) fiber-reinforced commer cially 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 inde pendent of interfacial shear stress, however, the tensile strength dep ended strongly on the interfacial shear stress. With increasing test t emperature, the interfacial shear stress decreased, a behavior which o riginated from an insufficient stress transfer between fiber and matri x due to decrease of shear yield stress of the matrix. The tensile str ength of the composite depended on the potential of shear stress trans fer at the interface, and the temperature dependence of the tensile st rength 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)sigma(fu)BAR /sigma(mu)L(g) almost-equal-to 0 where R(f) is the radius of fiber, si gma(fu)BAR is the mean tensile strength of fiber, sigma(my) is the yie ld stress of matrix, L(g) is the length of composite, the tensile stre ngth of the composite approaches the rule of mixture prediction for co ntinuous fiber-reinforced metals even at elevated temperatures. This r esult also indicated that the tensile strength of the composite depend ed strongly on the pge length of the composite L(g), and this tendency increased with decrease in the shear yield stress of the matrix.