Multistage Phase Decomposition Behavior and Kinetics for Zr65Ni30Pd5 Ternary Amorphous Alloy

Abstract

We have examined heating-induced phase decomposition and its kinetics for Zr 65 Ni 30 Pd 5 amorphous alloy in an argon atmosphere. The amorphous phase decomposes through three stages in the order of amorphous → icosahedral quasicrystal (I-Q) + amorphous → approximant cubic Zr 2 (Ni,Pd) → tetragonal Zr 2 Ni + tetragonal Zr 2 Pd phases. The approximant crystalline (APC) Zr 2 (Ni,Pd) phase includes icosahedral-like local atomic arrangements and the structural similarity between the I-Q and APC phases seems to enable the multistage phase decomposition through the precipitation of the APC phase. The primary precipitation of the I-Q phase from the amorphous phase occurs through nucleation and growth mechanisms through two-dimensional (2D) growth mode at lower heating rate and 3D growth mode at a high heating rate.