The Interactive Role of Inclusions and SiC Reinforcement on the High-Cycle Fatigue Resistance of Particle Reinforced Metal Matrix Composites

摘要

The effect of intermetallic inclusions on the fatiguecrack initiation and growth in 2080 Al alloy and 2080/SiC_pcomposites was investigated. Using surface replication, it wasdetermined that, in the high-cycle fatigue region, life is dominatedby the initiation process. It was also determined that the majorityof initiation sites were associated with intermetallic inclusions.While 2080/SiC/20_p showed a definitive relationship betweeninclusion size and fatigue life, i.e., a higher inclusion size resultedin lower fatigue life, there was no correlation in 2080/SiC/30_p.This was attributed to more of the load being shared by the highervolume fraction of SiC particles and smaller average inclusionsizes in the latter composite. A conceptual model is proposed thataccounts for these observations and qualitatively shows the effectof reinforcement on stress enhancement in near-surface inclusions.