Influence of zirconium on the growth of Al3Ti and TiB2 particles in aluminum alloys.

摘要

The effects of zirconium on the growth of Al3Ti and TiB2 particles in aluminum alloys are studied. Different experiments were designed to investigate the growth of Al3Ti and TiB2 particles in the presence of zirconium that was added either after or during the formation of the particles. The addition of zirconium, in form of K2ZrF6, leads to the growth Al3Ti particles in general. Additionally, the sequence of zirconium addition leads to different growth behaviors of Al3Ti. When zirconium is added after the formation of Al3Ti, Al3Zr forms on the surface of the Al 3Ti particles with well-defined surfaces and cracking of the particles occurred. In contrast, when zirconium and titanium are added together, irregular Al3(Zr,Ti) forms and higher density, even distribution and smaller sizes of Al3(Zr,Ti) particles can be seen in the microstructures. These growth behaviors are explained from the crystallographic differences of the two aluminide phases. The calculation of mismatching between ZrB 2 and TiB2 is also showed.