Correlative electron microscopy of discontinuous precipitation

Abstract

This paper presents a comprehensive study on discontinuous precipitation (DP) in Al-22 at.% Zn alloy, leveraging the correlative and synergic effects of advanced microscopy and modelling techniques. The study is structured into three pivotal steps: in-situ scanning electron microscopy combined with an energy backscattered diffraction analysis for real-time monitoring and an analysis of DP reaction kinetics and grain boundary misorientations; transmission electron microscopy and an energy X-ray dispersive microanalysis for detailed observation of solute-depleted α and solute-rich β lamellae, offering insights into the kinetics of the reaction front (RF) and solute concentration profiles; and a sophisticated modelling approach addressing the limitations of direct observation methods by simulating solute concentration changes within αphase lamellae during RF go-and-stop cycles. This multifaceted approach elucidates the nuances of DP mechanisms, from the nucleation and growth of precipitates to the estimation of instantaneous RF velocity and the impact of grain boundary misorientations. The integration of these methodologies enhances our understanding of DP kinetics and morphology at both meso- and nanoscales, highlighting the significant role of correlative microscopy in metallurgical research. The findings not only deepen our grasp of the fundamental mechanisms driving DP reactions but also provide a valuable comparison framework for experimental data, potentially guiding the development and optimization of metallurgical processes.