Effect of Applied Pressure and Nickel Coating on Microstructural Development in Continuous Carbon Fiber-Reinforced Aluminum Composites Fabricated by Squeeze Casting

Continuous carbon fiber reinforced aluminum composite samples were produced by squeeze casting method, under applied pressures of 30, 50, and 70MPa. For production of samples, nickel coated and uncoated carbon fibers with a mean volume fraction of 40% were used. After making the fiber preforms, they were preheated and then were replaced in a casting die. Molten 2024 aluminum alloy having a temperature of 750 degrees C was poured into the die, and different amount of pressures were applied to infiltrate the melt into the carbon fiber bundles. The effect of applied pressure on infiltration mechanism and microstructure of the composite were studied, by evaluating the cross-section of the composite samples, using optical and scanning electron microscopes (SEM). The appropriate applied pressures for producing the composite samples for uncoated and nickel coated fibers were different, and the best results were achieved at 50 and 30MPa, respectively. A specific or a certain range of pressure seems to be suitable for reaching to an appropriate microstructure in uncoated and coated samples. The results indicated that applying nickel coating on carbon fibers improves the infiltration of molten aluminum into the carbon fiber bundles and thus reduces the pressure required for infiltration significantly.