Real-Time Atomic Scale Imaging of Nanostructural Evolution in Aluminum Alloys

We present a new approach to study the three- dimensional compositional and structural evolution of metal alloys during heat treatments such as commonly used for improving overall material properties. It relies on in situ heating in a high-resolution scanning transmission electron microscope (STEM). The approach is demonstrated using a commercial Al alloy AA2024 at 100 − 240 ° C, showing in unparalleled detail where and how precipitates nucleate, grow, or dissolve. The observed size evolution of individual precipitates enables a separation between nucleation and growth phenomena, necessary for the development of re fi ned growth models. We conclude that the in situ heating STEM approach opens a route to a much faster determination of the interplay between local compositions, heat treatments, microstructure, and mechanical properties of new alloy