Abstract:

So far, only two orientation relationships (OR) between hexagonal close-packed (HCP) (α phase) and face-centered cubic (FCC) structures in zirconium and titanium alloys have been reported. Here a new type FCC phase (named γ phase) with OR: $<11\bar{2}0{{>}_{\text{ }\!\!\alpha\!\!\text{ }}}\parallel <100{{>}_{\text{ }\!\!\gamma\!\!\text{ }}}$ and ${{\{0001\}}_{\text{ }\!\!\alpha\!\!\text{ }}}\parallel {{\{002\}}_{\text{ }\!\!\gamma\!\!\text{ }}}$ was observed for the first time in annealed pure zirconium by means of transmission electron microscopy (TEM) technique. The α→γ phase transformation can be accomplished via expansion along $[1\bar{1}00]$ direction and slip of Shockley partial dislocation with 1/3 $[1\bar{1}00]$ on (0001) basal planes.

Key words: FCC phase, Orientation relationship, Phase transformation