Role of Ti and Y in the nucleation of the primary α-Al of Al7075–Ti–Y natural composites and influence of ultrasonic vibration

Abstract

Abstract Al7075–Ti–Y natural composites were prepared by using a combination of ultrasonic vibration and casting. The effects of titanium (Ti) and yttrium (Y) on the nucleation of primary α-Al were studied and the influencing mechanism of Y on the TiAl3 formation was analysed. Furthermore, a reaction kinetics model of TiAl3 under ultrasonic vibration was established. The results showed that the uniformly distributed TiAl3 and Al3Y nano-particles resulted in grain refinement. Y changed the morphology of TiAl3 and the appearance of corrosion pits was related to the fact that Y was dissolved within the TiAl3 structure to form Ti(Al,Y)3. The established model revealed that ultrasonic vibration significantly promoted the formation of TiAl3, and that ultrasonic time was the main factor affecting its growth.