Especially the far-from-equilibrium conditions during AM processes pose significant challenges, including rapid thermal cycling and extreme thermal gradients leading to anisotropic microstructures and the formation of unexpected or metastable phases. Predicting the relationships between (post-)process parameters, microstructure, and properties remains difficult.

To address these challenges, we develop in-situ electron microscopy (EM) techniques supported by COMSOL multiphysics simulations to recreate AM-specific thermal conditions. These simulations serve as a tool to understand microstructure evolution and optimize AM processes. Our research focuses on in-situ observations of far-from-equilibrium thermal phenomena using a MEMS-based SEM/TEM heater. First, we have established approaches on how we can measure the temperature in SEM/TEM specimen. Further, by comparing AM thermal parameters with the capabilities of this heater, we demonstrate the feasibility of groundbreaking experiments. Preliminary results and COMSOL simulations demonstrate that in-situ heating experiments can realistically replicate AM thermal profiles and provide important data for updating phase- and time-temperature diagrams, which are essential for predicting AM microstructures.

Our research approach focuses on developing precise in-situ temperature measurements for real-time analysis of thermal gradients and then performing in-situ SEM/TEM heating experiments under far-from-equilibrium conditions to replicate AM conditions.

The aim of our study is to better understand AM microstructures in order to make significant progress in predicting process-structure-property relationships and thereby gain systematic control over AM processes.