Formation of Quasicrystals in Zr-Ti-Nb-Cu-Ni-Al Melt-Spun and Ball-Milled Multicomponent Alloys

摘要

Amorphous Zr-Ti-Nb-Cu-Ni-Al alloys were prepared by melt spinning, mechanical alloying of elemental powder mixtures and ball milling of crystalline prealloys. The devitrification of the melt-spun ribbons is characterized by the formation of a metastable nanoscale quasicrystalline phase during the first stage of the crystallization process, followed by successive transformation into intermetallic compounds at higher temperatures. In contrast, no clear quasicrystal formation was observed in the first step of crystallization for the mechanically alloyed powders produced by using different milling conditions. Conversely, the ball-milled crystalline prealloy precipitates the same icosahedral phase displayed as found for the as-prepared ribbon.