Characterization of tensile fracture in heavily alloyed Al-Si piston alloy

This paper focuses on a typical automotive piston material to characterize its fractographic appearance after tensile rupture. The fracture of this heavily alloyed Al-Si alloy takes place in a brittle manner. The consecutive eutectic zone is found to break by debonding of Si platelets from the Al matrix or by fracturing of Si platelets. The various intermetallic particles break up complicatedly under the stress field of the propagating crack. The fracture tends to pass through or approach to the boundary between the eutectic Al matrix and Si platelets and there is a strong interaction between the propagating crack and the obstructing intermetallic compound. A tensile fracture mechanism in the heavily alloyed Al-Si alloy is elucidated.