On the Feasibility of Extreme Heating Rates in SEM using MEMS Heater Platforms

TL;DR

This paper demonstrates that MEMS heater platforms can achieve rapid, stable heating in SEM for in-situ microstructural studies, enabling new insights into phase transformations during additive manufacturing.

Contribution

It introduces a MEMS-based heating method for SEM that allows stable, high-rate thermal cycling of samples with minimal power and high accuracy, suitable for studying AM processes.

Findings

Achieved stable heating/cooling rates up to 1000°C/s in SEM.

Confirmed surface temperature closely follows MEMS setpoint.

Enabled in-situ EBSD analysis during rapid thermal cycling.

Abstract

Understanding microstructural evolution under extreme thermal conditions is essential for advancing metal additive manufacturing (AM). 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 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 establish MEMS-based heating as a robust approach for in-situ microstructural characterization of AM-relevant thermal processes in the SEM, enabling quantitative studies of thermally activated phenomena such as diffusion, phase transformations, and microstructural evolution under far-from-equilibrium conditions.