The effects of volume fraction and particle size of SiC on fatigue crack propagation behavior in SiC-particulate-reinforced 2024-T6 aluminum alloys were investigated. The volume content of SiC was 0, 10, 20 and 30% with two groups of different particle size respectively. At the same stress intensity range, ΔK, the crack propagation rate, da/dN, decreases with increasing volume fraction of SiC particle. For the same volume fraction, the crack propagation rate in the composite with coarse SiC particle is lower than that with fine particle. The crack opening stress intensity factor divided by the maximum stress intensity factor increases with increasing volume fraction of SiC particles. Reinforcement increased the crack closure. The relationship between da/dN and ΔK
eff/E was almost identical for all materials except coarse particle-reinforced composites. At the same ΔK
eff/E, the crack propagates faster in coarse particle-reinforced composites than in the fine particle-reinforced composites and the unreinforced matrix. The threshold stress intensity range ΔK
th, increases with the volume fraction of SiC particles due to the development of crack closure. The roughness of fatigue fracture surfaces at the threshold also increases with increasing the volume fraction of SiC particle.
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