An Initial Report on the Oriented-Precipitation of T1-Phase in Creep-Aged Al-Cu-Li Single Crystal

Abstract

In this work, the precipitation behavior of the T1 -phase on each {111} Al habit plane was characterized by transmission electron microscopy (TEM), which was observed along two <110> Al zone axes in an Al-Cu-Li single crystal during creep aging. The results indicate that the oriented-precipitation of T1 -phase was found in the Al-Cu-Li single crystal during creep aging. The number density of the T1 -phase on the habit planes of (111) Al and (1[[EQUATION]]1) Al is significantly higher than that of the T1 -phase on the habit planes of ( [[EQUATION]]11) Al and (11[[EQUATION]] ) Al in the same Al-Cu-Li single crystal when the external stress is loaded along close to [111] Al orientation. It suggests that the T1 -phase tends to preferentially precipitate on the habit planes that are perpendicular to the loading orientation during creep aging. This work provides the initial experimental evident of the oriented-precipitation of the T1 -phase in Al-Cu-Li alloy, and proposes the possibility of regulating the precipitation distribution of the T1 -phase.

Keywords: Al alloy, T1-phase, single crystal, creep aging, oriented-precipitation