Mechanism and kinetic model of in-situ TiB₂/7055Al nanocomposites synthesized under high intensity ultrasonic field

Abstract

In-situ TiB₂/7055Al nanocomposites are fabricated by in situ melt chemical reaction from 7055Al-K₂TiF₆-KBF₄ system under high intensity ultrasonic field, and the mechanism and kinetic model of insitu melt chemical reaction are investigated. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses indicate that the sizes of in-situ TiB₂ nanoparticles are in the range of 80–120 nm. The results of icewater quenched samples show that the whole process contains four stages, and the overall in-situ reaction time is 10 minutes. The in situ synthesis process is controlled mainly by chemical reaction in earlier stage (former 3 minutes), and by the particulate diffusing in later stage. The mechanism of key reaction between Al₃Ti and AlB₂ under high intensity ultrasonic in the 7055Al-K₂TiF₆-KBF₄ system is the reaction-diffusion-crack-rediffusion. Furthermore, the reactive kinetic models in 7055Al-K₂TiF₆-KBF₄ system are established.

Keywords

in-situ nanocomposites / high intensity ultrasonic field / reactive mechanism / kinetic model

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