Triangularly arranged needle-shaped precipitates in Ge containing zirconium alloy

Abstract

Novel triangularly arranged needle-shaped precipitates in zirconium based alloys were firstly observed and systematically investigated, which were indexed as single hexagonal structured ω phase while obeying the orientation relationship with the α phase matrix: {0001}α∥{112‾0}ω and <112‾0>α∥<0001>ω. In particular, viewed along [0001]ω zone axis, the ω phase needles were 60° triangularly arranged and paralleled to (21‾1‾0)ω, (112‾0)ω and (1‾21‾0)ω planes, respectively. Based on electron microscopy analysis, a model for understanding the formation of these precipitates was proposed: planar periodicity distribution of dissimilar atoms in these ω phase needles resulted in the needle-shaped morphology as well as the triangular arrangement.