Novel −75°C SEM cooling stage: application for martensitic transformation in steel

Abstract

Microstructural changes during the martensitic transformation from face centred cubic (FCC) to body centred cubic (BCC) in an Fe–31Ni alloy were observed by scanning electron microscopy (SEM) with a newly developed Peltier stage available at temperatures to −75 °C. Electron channelling contrast imaging (ECCI) was utilized for the in situ observation during cooling. Electron backscatter diffraction (EBSD) analysis at ambient temperature (20 °C) after the transformation was performed for the crystallographic characterization. A uniform dislocation slip in the FCC matrix associated with the transformation was detected at −57 °C. Gradual growth of a BCC martensite was recognized upon cooling from −57 °C to −63 °C.

Stacking fault aggregation during cooling composing FCC–HCP martensitic transformation revealed by in-situ electron channeling contrast imaging in an Fe-high Mn alloy

“…After heating for reverse transformation, the specimen was mechanically polished with colloidal silica with a particle size of 60 nm. The polished specimen was set to a cooling stage (produced by the Mel-Build Corporation, Japan [ 23 ]) to conduct in situ ECCI during cooling from room temperature (20°C) to −51°C in the scanning electron microscope (Carl Zeiss Co., Ltd., Germany). The temperature was held within an accuracy of ±0.1°C for each observation.…”