Quantitative Analysis of Precipitate Compositions in an Al-Li-Mg-Cu Alloy Using Atom Probe Tomography

Abstract

The composition of  precipitates in aluminium alloy 8090 has been analysed using a 3 dimensional atom probe with fast data acquisition rates. The effects of experimental conditions for the quantitative atom probe analysis have been examined in detail. The results show that i) lithium is prone to preferential DC field evaporation at temperatures > 25K and with a pulse fraction < 20%; ii) the lithium concentration of  precipitates can vary from precipitate to precipitate, ranging from 19.1 to 25.3 at.%, and iii) the stoichiometric composition of the  phase can be obtained provided that the probing temperature is  25K and pulse fraction is  20%.