Strain-induced preferential dissolution at the dislocation emergences in MnS: an atomic scale study

Abstract

The long-standing problem of dislocation-preferential dissolution in a crystal has been generally ascribed to the distortion energy stored in the vicinity of the dislocation core. However, due to lack of experimental means, the relationship between the local distortion state and the electrochemical behaviour of a single dislocation has not been established so far. via in situ ex-environment transmission electron microscopy (TEM), we demonstrate that the emergences of both edge and screw dislocations on MnS surfaces are the preferential sites for dissolution of the MnS inclusions within a stainless steel. In addition, we map the strain-induced variation of the standard electrode potential around the edge dislocation by a combination of the aberration-corrected high-resolution TEM and strain-analysis-based mechanochemistry theory. Significantly, our report provides a new approach to investigate the strain-corrosion correlation at an atomic scale.

Grain Boundary Motion in Two-Dimensional Hexagonal Boron Nitride

“…53 Strain Energy Estimation in Grains. The strain energy of the grain next to a GB was estimated following the method proposed by Zhou et al, 54 which can be written as w e = 1/2λ(ε xx + ε yy ) 2 + μ(ε xx 2 + ε yy 2 + 2ε xy 2 ), where λ = 2μν/(1 − 2ν), μ = E/(2(1 + ν), and E and ν are the Young's modulus (278.3 GPa) and Poisson's ratio (0.2254) for monolayer h-BN, 55 respectively. The components of the strain tensor, ε xx , ε yy , ε xy , were calculated by geometric phase analysis (GPA).…”

Corrosion Behavior of Severely Deformed Pure and Single-Phase Materials

“…In another approach using high-angle-annular-dark-field (HAADF)-TEM, Zhou et al estimated the local potential drop at a single dislocation core to be almost 100 mV. 44) In in situ observations by EC-STM, corroded topographic features resulting from nanoscale local dissolution or local passivation at a single grain boundary were observed. 4951) It was shown that random grain boundaries develop thicker passivation than coherent grain boundaries in microcrystalline copper.…”

“…5) Dislocations and grain boundaries locally have high stored energy, and they can form galvanic couples with the surrounding perfect crystals. 44,45) The nanoscale potential distribution has recently been determined by a Kelvin probe force microscopy, 46,47) scanning Kelvin probe microscopy (SKEM), 48) nanoscale galvanic cells between grain boundaries and dislocations with the surrounding matrix have been revealed by in situ observation using electrochemical scanning tunneling microscopy (ECSTM), 4951) scanning transmission electron microscopy (STEM), 52) and open-loop electric potential microscopy (OL-EPM). 53,54) These experimental results validate the hypothesis that nonuniformity of electron activity is maintained to nanoscale structures with sufficient potential difference to form galvanic cells.…”

Application of In Situ Liquid Cell Transmission Electron Microscopy in Corrosion Studies: A Critical Review of Challenges and Achievements

“…However, due to limiting factors such as a thin object size (5-300 nm) and the vacuum operating conditions, practical TEM corrosion studies were ex-situ typically, i.e. after the corrosion event, and of dehydrated surfaces (post-mortem characterizations) [10][11][12][13][14][15][16] . Thus, concluding statements are sometimes uncertain and debatable when compared to the real-life conditions since active solid/electrolyte interfaces cannot be evaluated real-time in such ex-situ studies.…”