Redistribution behavior of constitutional elements at an initial crystallization stage in the Zr₆₅Al_7.5Ni₁₀Cu_17.5 glassy alloy

We investigated the transformation behavior from glassy to Zr₂Ni phase in the Zr₆₅Al_7.5Ni₁₀Cu_17.5 glassy alloy with a low oxygen content below 400 ppm mass%. The mostly single face centered cubic Zr₂Ni phase precipitated as a primary phase at the initial crystallization stage. The Zr₂Ni particles had a cubical morphology in the diameter range of 300 to 500 nm and were in an isolated state for the sample annealed at the temperature near crystallization temperature. A significant redistribution leading to the enrichment of Zr and Ni into the Zr₂Ni phase is confirmed. Moreover, it is recognized that Cu and Al are rejected from the Zr₂Ni phase. The compositional differences of Zr, Al, Ni, and Cu between the Zr₂Ni and remaining glassy phases are in the range of 1.5 to 5 at.%. It is strongly suggested that such a significant redistribution of the constitutional elements restrains the nucleation and growth of crystalline phases. It is one of the important factors for the stabilization of the glassy state in Zr-Al-Ni-Cu alloy.