Fatigue Behavior of Ni-P Coated Si3N4 Reinforced Al6061 Composites

Abstract

Ni–P coated Si3N4 reinforced Al6061 composites were fabricated by stir casting technique. Silicon nitride particles were varied in steps of 2 from 6wt.% to 10wt.%. Cast matrix alloy and developed composites were hot forged at a temperature of 500̊C using a 300T hydraulic hammer. Both as cast, hot forged matrix alloy and its composites were subjected to microstructural studies and fatigue strength tests. Microstructural studies reveal even distribution of silicon nitride particles with excellent bond between the matrix and reinforcement in both as cast and hot forged condition. It is observed that, increased content of reinforcement in both as cast and hot forged composites do result in significant improvement in fatigue strength. However, when compared with as cast matrix alloy and its composites, hot forged alloy and its composites exhibit higher fatigue strength. Both as cast and hot forged composites demonstrate improved fatigue strength when compared with the unreinforced alloys under identical test conditions. Fractured surfaces were examined using scanning electron microscopy (SEM) for the possible fracture mechanisms.