In situ weak-beam scanning transmission electron microscopy observation of geometrically necessary dislocations formed by Mn precipitates in A533B alloy steel
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引用次数: 0
Abstract
In this study, the Charpy impact test was performed for mechanically introducing cracks in A533B steel. Then, in situ weak-beam scanning transmission electron microscopy (WB-STEM) annealing tests were performed from room temperature to 600 °C. A wide area surface polishing method that did not require chemical polishing or resin-filling process for bulk specimens were developed for microsampling a 200 nm thin film. The film was sampled from the strain site at the crack tip (EBSD-KAM value: 2.7°) via Focus ion beam-scanning electron microscopy (FIB-SEM), i.e., the inhomogeneous plastic deformation zone of dislocation density above 2.5 × 1016 /m2 formed by Mn precipitates. In isochronous annealing process imaging, the dynamic behavior of dislocations was successfully visualized using movie files with a spatial resolution of 0.4 nm/pixel and a temporal resolution of 1s/frame via WB-STEM. Results revealed thermal relaxation of local strain as high density dislocations deformed into new subgrain boundaries via the geometrically necessary dislocation network at control temperatures from 500 °C to 550 °C.
期刊介绍:
Materialia is a multidisciplinary journal of materials science and engineering that publishes original peer-reviewed research articles. Articles in Materialia advance the understanding of the relationship between processing, structure, property, and function of materials.
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