Article ID Journal Published Year Pages File Type
7986258 Micron 2018 20 Pages PDF
Abstract
This paper reports on the in situ observation of phase transformation in an iron carbide nanocrystal encapsulated in a graphitic shell by means of high resolution transmission electron microscopy (HR-TEM). A Fe7C3 nanocrystal in orthorhombic (o-Fe7C3) structure with carbon graphitic cover is captured at the initial time of the experiment. Under the projection of a high-energy electron beam (200 kV), the graphitic carbon layer evaporates gradually and structural changes in orthorhombic (o-Fe7C3) crystal manifests simultaneously. Specifically, changes in crystal direction happens first and then the crystal structure switching between orthorhombic and hexagonal (h-Fe7C3) follows. Details analysis and conclusive evidences of the phase structure and transformation are presented and discussed. The appearance of o-Fe7C3 structure is captured for about 92 min over 100 min of observation, indicating the preference of o-Fe7C3 form over h-Fe7C3 form.
Related Topics
Physical Sciences and Engineering Materials Science Materials Science (General)
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