Kinetic study of the infiltration of aluminum alloys into TiC preforms

A study of the infiltration process of several alloys (Al-2024, Al-6061, and Al-7075) into preforms of TiC was carried out. The preforms were sintered for one hour under argon at 1250, 1350, and 1450 degrees C with the aim of achieving different levels of densification. Using a thermogravimetric analyzer (TGA), infiltration profiles were obtained by continuously monitoring the weight change of preforms partially immersed in molten aluminum. Infiltration was carried out at different temperatures (ranging from 900 to 1200 degrees C) under argon to evaluate infiltration kinetics. The infiltration rate of the aluminum into the preforms followed parabolic behavior and the activation energy changed according to the extent of preform densification. Average activation energies of 74, 99, and 138 k J mol(-1) were obtained for the Al-7075, Al-6061, and Al-2024 alloys, respectively. Prior to infiltration, an incubation period was observed and its length depended on the temperature; lower the infiltration temperature, longer was the incubation period.