Study on the yield behavior of Al2O3–SiO2(sf)/Al–Si metal matrix composites

As the yield behavior of Al₂O₃–SiO₂(sf)/Al–Si MMCS is concerned, effects of heat treatment and parameters of short fiber, including volume fraction, size, distribution mode, were investigated. Dislocation configurations adjacent to interface between matrix and fiber were observed by TEM. Macro-yield stress (σ_0.2) and micro-yield stress (σ_MYS) vary with parameters of short fiber, and effects of these parameters on σ_0.2 appear to be opposite to those on σ_MYS. This phenomenon was interpreted by thermal residual stress in matrix and dislocation configuration. Suitable quenching followed aging treatment is an effective method to enhance the σ_MYS and the σ_0.2 simultaneously. For the specimen with heat treatment of 550 °C/1 h WQ + 170 °C/6 h (T6) AC, σ_0.2 and σ_MYS reach 200 and 58 MPa, respectively, and they are almost as twice as those as-cast.