Atom probe microscopy investigation of Mg site occupancy within {\delta} precipitates in an Al Mg Li alloy

TL;DR

This study combines atom probe microscopy and first-principles simulations to reveal that Mg atoms preferentially occupy Li sites within { extstyle ext{δ}} precipitates in an Al Mg Li alloy, providing insights into atomic site occupancy.

Contribution

It is the first to experimentally and theoretically demonstrate Mg's site preference for Li sites in { extstyle ext{δ}} precipitates in this alloy system.

Findings

Mg partitions to Li sites in { extstyle ext{δ}} precipitates.

Density functional calculations confirm energetic favorability of Mg occupying Li sites.

Mg concentration in precipitates is similar to the matrix.

Abstract

The composition and site occupancy of Mg within ordered {\delta} precipitates in a model Al Mg Li alloy have been characterized by atom probe microscopy and first-principles simulations. The concentration in the precipitates is found to be almost the same as that of the matrix, however, we show evidence that Mg partitions to the sites normally occupied by Li in the L12 structure. Density functional calculations demonstrate that this partition is energetically favorable, in agreement with experimental results.