Low-cycle fatigue behavior of SiCp/Al–Si composites produced by spray deposition

In this research, the low-cycle fatigue life and cyclic stress response of SiCp/Al–Si composites produced by spray deposition were investigated in comparison to the unreinforced alloy. Both the composite and matrix alloy display cyclic hardening under total-strain amplitude 0.35–0.5%. However, under low strain amplitude (0.3%), the Al–Si alloy shows cyclic stable after the initial hardening for 200 cycles. In contrast, the composite displays cyclic hardening immediately at the beginning of cyclic loading and a secondary hardening is also observed prior to fatigue fracture. Due to the higher density of pre-existing dislocations, interaction of mobile dislocations with the reinforcing SiC particles and more dislocation–dislocation interactions, a more pronounced strain-hardening behavior was observed for the composite. Moreover, both composite and matrix alloy follow the Coffin–Manson relationship. Fatigue damage parameter indicates the inferior life in the low-cycle regime for the composite, compared to the unreinforced alloy. Fractographic analysis shows that particle/matrix debonding is the main mechanism of failure in the SiCp reinforced composite.

Research highlights▶ The present study is to investigate the differences in low-cycle fatigue behavior of SiCp/Al–Si composite and its matrix alloy produced by spray deposition, which are rarely reported. ▶ Different from those of composite prepared by casting, the cyclic response characteristics for the composite and alloy is similar to each other. ▶ Moreover, spray deposition technology adopted in this study provides finer microstructure, circular geometry of Si phase and uniform distribution of SiC, then results in better cyclic-strain resistance than the as-cast composite [21].