Abstract
Reversed plane bending fatigue tests were carried out on three kinds of particle-reinforced aluminum matrix composites, Si/A2024, SiC/A2024 and SiC/AC4CH. SiC/A2024 and two kinds of Si/A2024 which have different size and distribution of Si particles were consolidated by Powder Metallurgy(PM) process, and SiC/AC4CH was made by casting process. The initiation and growth behavior of small surface cracks was continuously monitored by the replication technique and investigated in detail. It was found that both fatigue crack initiation strength and crack growth resistance became higher in the order, SiC/AC4CH, , Si/A2024 with coarse Si particle, Si/A2024 with fine Si particle, SiC/A2024. When stress amplitude was normalized by tensile strength, the difference in the fatigue strength of P/M composites was scarcely observed, but the casting composite exhibited lower strength than P/M one.
