Grain Refinement Efficiency in Commercial-Purity Aluminum Influenced by the Addition of Al-4Ti Master Alloys with Varying TiAl(3) Particles

A series of Al-4Ti master alloys with various TiAl(3) particles were prepared via pouring the pure aluminum added with K(2)TiF(6) or sponge titanium into three different molds made of graphite, copper, and sand. The microstructure and morphology of TiAl(3) particles were characterized and analyzed by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). The microstructure of TiAl(3) particles in Al-4Ti master alloys and their grain refinement efficiency in commercial-purity aluminum were investigated in this study. Results show that there were three different morphologies of TiAl(3) particles in Al-4Ti master alloys: petal-like structures, blocky structures, and flaky structures. The Al-4Ti master alloy with blocky TiAl(3) particles had better and more stable grain refinement efficiency than the master alloys with petal-like and flaky TiAl(3) particles. The average grain size of the refined commercial-purity aluminum always hereditarily followed the size of the original TiAl(3) particles. In addition, the grain refinement efficiency of Al-4Ti master alloys with the same morphology, size, and distribution of TiAl(3) particles prepared through different processes was almost identical.