Failure mechanism and tensile constitutive model of the unidirectional-laminated Cf/SiC–Al composites

Abstract

The unidirectional-laminated Cf/SiC–Al composites were prepared by using precursor infiltration and pyrolysis (PIP) and vacuum pressure infiltration processes. Bulk density and open porosity of as-prepared Cf/SiC–Al composites were characterized which showed a large number of pores in the unidirectional-laminated carbon fiber preform were filled with SiC and Aluminum alloy matrix. The uniaxial tensile tests were conducted to study the mechanical properties. The fracture surface and cross-section of tensile specimens were characterized to clarify the failure mechanism. The results showed that under the action of load, the propagation of microcracks in matrix led to interface debonding, fiber fracture and pull-out. According to the stress-displacement behavior and analysis of damage process, the prediction formulas of the linear proportional limit stress value and the tensile strength value were proposed. A bilinear constitutive model was established based on the assumption of the damage process which well characterized constitutive response of the composites.