Application of high-spatial-resolution secondary ion mass spectrometry for nanoscale chemical mapping of lithium in an Al-Li alloy

Abstract

High-spatial-resolution secondary ion mass spectrometry offers a method for mapping lithium at nanoscale lateral resolution. Practical implementation of this technique offers significant potential for revealing the distribution of Li-containing nanoscale precipitates in Al-Li alloys with exceptional lateral resolution and elemental sensitivity. Here, two state-of-the-art methods are demonstrated on an aluminium-lithium alloy to visualise nanoscale Li-rich phases by mapping the 7 Li + secondary ion. NanoSIMS 50L analysis with a radio frequency O − plasma ion source enabled visualisation of needle-shaped T 1 (Al 2 CuLi) phases as small as 75 nm in width. A compact time-of-flight secondary ion mass spectrometry detector added to a focused ion beam scanning electron microscope facilitated mapping of the T 1 phases down to 45 nm in width using a Ga + ion beam. Correlation with high resolution electron microscopy confirms the identification of T 1 precipitates, their sizes and distribution observed during SIMS mapping. • High-lateral-resolution SIMS was used to characterise Li distribution in nanoscale. • The observations from SIMS were validated using correlative electron microscopy. • NanoSIMS visualises Li-rich T 1 (Al 2 CuLi) phases as small as 75 nm in size. • FIB ToF-SIMS visualises intergranular T 1 precipitates as small as 45 nm in size. • STEM-EDX analysis provides complementary information of phase chemistry.