The Role of Microstructural Variability on the Very High-Cycle Fatigue Behavior of Discontinuously-Reinforced Aluminum Metal Matrix Composites using Ultrasonic Fatigue (Preprint)
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH METALS BRANCH
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The fatigue behavior of two 2009SiC15p-T4 DRA composites has been investigated in the very high cycle fatigue regime using ultrasonic fatigue to achieve the very high cycle counts. One composite displayed a very homogeneous spatial distribution with minimal particle clustering and the other displayed a relatively heterogeneous distribution with significant particle clustering. Fatigue cracks initiated almost exclusively at A1CuFe inclusions in the homogeneous material and no crack initiation was observed at SiC particle clusters. Conversely, fatigue cracks initiated almost exclusively at clusters of SiC particles in the heterogeneous material and no crack initiation at inclusions was observed. Fatigue lives in both composites approaching 10 to the 9th cycles exhibited minimal variation in lifetime and subsurface crack initiation was observed in all cases. Differences in the crack initiation behavior between the two composites were attributed primarily to variations in the spatial distribution of the reinforcement phase.
- Laminates and Composite Materials
- Properties of Metals and Alloys