Tecnai g2 f20 s twin

The heat-treated plates were obtained by wire cutting, ground to a roughness of 106 μm, 45 μm, 23 μm and 13 μm, and then polished, followed by soaking in aqueous solution of CuCl₂ and hydrochloric acid for 10 s. The original structure of the steels were observed by a digital metallographic microscope (Zeiss 40MAT, Carl Zeiss AG, Oberkochen, Germany), at 50 times of magnification.
A thermal field emission scanning electron microscope (FEI-Quanta650, Thermo Fisher Scientific, Waltham, MA, USA) was used to observe the above samples at a magnification of over 1000 times. The SEM mode was secondary electronic imaging, with the working distance 10–15 mm, the magnification 5000 times, and the acceleration voltage 20 kV.
The microstructure was characterized by transmission electron microscope (TEM, Tecnai G2 F20 S-TWIN, Thermo Fisher Scientific, Hillsboro, OR, USA). The steel block samples were cut to 0.5 mm, then thinned by 13 μm sandpaper to 50 μm, then cut into a circle with a diameter of 3 mm. The Automatic Twin-Jet Electropolisher (MTP-1A, BUEHLER, Lake bluff, IL, USA) was used for double spray, with the current 40 mA, the voltage 20 V, the experimental temperature −20 °C, and the experimental solution 10% perchloric acid. The obtained samples were observed at an operating voltage of 200 kV.

The samples were characterized by means of powder XRD analysis (Rigaku Ultima IV, Japan; Cu Kα radiation, λ = 1.5418 Å), Field-emission SEM (Hitachi SU5000, Japan), TEM and HRTEM with EDS (FEI Tecnai G2 f20 s-twin, 200 KV), XPS (Thermo SCIENTIFIC ESCALAB 250Xi, Al Ka X-ray monochromator), BET (Autosorb-IQ, USA).