On the feasibility of extreme heating rates in SEM using MEMS heater platforms

Understanding microstructural evolution under extreme thermal conditions is essential for predicting and controlling metallic microstructures. This work demonstrates the feasibility of employing micro-electro-mechanical system (MEMS) heating platforms for in-situ scanning electron microscopy (SEM) characterization of bulk-like samples during rapid thermal cycling. Using electron backscatter diffraction (EBSD), we tracked the ferrite-to-austenite phase transformation in a pure iron specimen (≈ 100 × 100 × 5 μm³) and confirmed that the sample surface temperature closely follows the MEMS temperature setpoint within device accuracy. Under vacuum conditions, stable heating and cooling rates of up to 1000 °C/s were achieved with minimal power input and without compromising EBSD pattern quality. These findings demonstrate that MEMS-based heating in the SEM provides a robust platform for in-situ microstructural characterization across a wide range of applications, including AM-relevant thermal processes, by enabling quantitative studies of thermally activated phenomena such as diffusion, phase transformations, and microstructural evolution under far-from-equilibrium conditions.