Fatigue Behavior of Squeeze Cast Metal Matrix Composites for Diesel Pistons

The tensile and fatigue strengths of squeeze cast metal matrix composites (MMC's) containing 0 and 15 volume percent of discontinuous Fiberfrax^® ceramic fibers in an F332 T5 aluminum alloy matrix were determined at room temperature and 350°C. Rotating beam fatigue testing was performed using the up-and-down modified staircase method to determine the fatigue strength of these composites for 50% probability of failure at 10⁷ cycles.

Significant improvements in tensile and fatigue strengths were measured for the MMC material compared to the unreinforced alloy. The statistical variation in the measured fatigue strengths of the MMC material was equivalent to that of the unreinforced alloy, indicating the high degree of reproducibility of the manufacturing process.