Evolution of silicon particle damage on fatigue crack initiation and early propagation in an aluminum alloy

Low-cycle fatigue tests under both mechanical cyclic and thermal cyclic loadings were conducted to study the behavior of fatigue crack initiation and early propagation by means of metallographic and scanning electron microscopy (SEM). The damage mode of silicon particles has significant influence on crack behavior. Cracks are induced from fractured particles in mechanical fatigue or from debonded particles in thermal fatigue. Initiation of cracks by breaking through particles happens in particles with non-equiaxial particles, while initiation of cracks from debonded interfaces happens widely in clustered particles. For cracks induced by fracture particles, the subsequent coalescence of microcracks proceeds through the alternation of brittle fracture of particles. The sequent broken of particles takes the important part in the early propagation stage of fatigue crack.

Automated summary

Low-cycle fatigue tests were conducted to investigate fatigue crack initiation and early propagation behavior under mechanical cyclic and thermal cyclic loadings. Metallographic and scanning electron microscopy (SEM) were used for analysis. The damage mode of silicon particles plays a significant role in crack behavior, with cracks induced by fractured particles in mechanical fatigue and debonded particles in thermal fatigue. The initiation of cracks varies depending on the particle morphology, while the subsequent coalescence of microcracks is primarily controlled by the brittle fracture of particles. The broken sequence of particles is crucial during the early propagation stage of fatigue crack.