Dislocation Nucleation on Grain Boundaries: Low Angle Twist and Asymmetric Tilt Boundaries

Guleryuz, Erman; Mesarovic, Sinisa Dj.

doi:10.3390/cryst6070077

Cited by 14 publications

(8 citation statements)

References 40 publications

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“…For 0.5Mo and Mo–Nb steels, there was no such decrease and the low‐angle boundaries can be assumed to be composed of an array of dislocations. [ 20,21 ] In our study, EBSD data further verified that microalloying with Mo and Mo–Nb hindered the annihilation and movement of dislocations during the tempering process. As mentioned previously, the strongest pinning effect of dislocations was achieved with the combined alloying of Nb and Mo.…”

Section: Resultssupporting

confidence: 75%

Evaluation of Mechanical Properties and Microstructures of Direct‐Quenched and Direct‐Quenched and Tempered Microalloyed Ultrahigh‐Strength Steels

Hannula

Kaijalainen

Porter

et al. 2020

steel research int.

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Herein the effects of molybdenum and niobium on the microstructures and mechanical properties of laboratory‐rolled and direct‐quenched and direct‐quenched and tempered steels are revealed. The microstructures are martensitic with yield strength of 766–1119 MPa in direct‐quenched condition and 632–1011 MPa in direct‐quenched and tempered condition. Mo and Nb additions lead to a fine martensitic microstructure that imparts a good combination of strength and toughness. Steel with 0.5 wt% molybdenum has a high yield strength of 1119 MPa combined with low 28 J transition temperature of −95 °C in direct‐quenched condition. Molybdenum and niobium increase the strength significantly during tempering due to enhanced solute drag and precipitation hardening. Addition of 0.25 wt% molybdenum increases yield strength from 632 to 813 MPa after tempering. However, the combination of niobium and molybdenum results in even greater increase in yield strength during tempering compared to the nonalloyed version, producing almost 400 MPa increase in yield strength. Transmission electron microscopy reveals that only niobium forms stable precipitates during tempering, indicating that molybdenum largely remains in solution. X‐ray diffraction analysis elucidates that molybdenum and molybdenum–niobium alloying prevents annihilation of dislocations, leading to the presence of high densities of dislocations after tempering.

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Section: Resultssupporting

confidence: 75%

Evaluation of Mechanical Properties and Microstructures of Direct‐Quenched and Direct‐Quenched and Tempered Microalloyed Ultrahigh‐Strength Steels

Hannula

Kaijalainen

Porter

et al. 2020

steel research int.

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“…The inhomogeneity of GBs dislocation distribution among different grain boundaries may be attributed to differences of grain boundary structures and orientations. Several MD results have shown that the value of nucleation stress of GBs dislocations varies greatly with the grain boundary structure and inclination angles [32][33][34]. As the indentation depth was further increased, the plastic regime initiates.…”

Section: Indentation Stagementioning

confidence: 99%

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

et al. 2017

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Using embedded atom method potential, extensive large-scale molecular dynamics (MD) simulations of nanoindentation/nanoscratching of nanocrystalline (nc) iron have been carried out to explore grain size dependence of wear response. MD results show no clear dependence of the frictional and normal forces on the grain size, and the single-crystal (sc) iron has higher frictional and normal force compared to nc-samples. For all samples, the dislocation-mediated mechanism is the primary cause of plastic deformation in both nanoindentation/nanoscratch. However, secondary cooperative mechanisms are varied significantly according to grain size. Pileup formation was observed in the front of and sideways of the tool, and they exhibit strong dependence on grain orientation rather than grain size. Tip size has significant impact on nanoscratch characteristics; both frictional and normal forces monotonically increase as tip radii increase, while the friction coefficient value drops by about 38%. Additionally, the increase in scratch depth leads to an increase in frictional and normal forces as well as friction coefficient. To elucidate the relevance of indentation/scratch results with mechanical properties, uniaxial tensile test was performed for nc-samples, and the result indicates the existence of both the regular and inverse Hall-Petch relations at critical grain size of 110.9 Å . The present results suggest that indentation/scratch hardness has no apparent correlation with the mechanical properties of the substrate, whereas the plastic deformation has.

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“…In addition, dislocation nucleation is often observed at the GB [35][36][37]. Atomic simulation of Cu and Al under uniaxial tension perpendicular to a Σ3 GB shows [35] that dislocation nucleation at these boundaries is connected with the GB structure and energy, as well as mechanical properties of the metal.…”

Section: Dislocations Interacting With Lagbsmentioning

confidence: 99%

Interaction of Dislocations and Interfaces in Crystalline Heterostructures: A Review of Atomistic Studies

et al. 2019

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Interfaces in heterostructures of crystalline materials could strongly affect the slip of dislocations. Such interfaces have become one of the most popular methods to tailor material strength and ductility. This review focuses on the interaction of dislocations and interfaces in heterostructures, in which at least one component is metallic, as investigated by molecular dynamics, in order to systematically summarize our understanding about how dislocations interact with the interfaces. All the possible heterostructures of metallic materials are covered, such as twin boundaries, grain boundaries, bi-metal interfaces and metal/non-metal interfaces. Dislocations may either penetrate the interfaces by inducing steps into the interfaces or dissociate within the interfaces, depending on the type and orientation of the interface as well as the applied strain. Related dislocation interactions at the interface are also presented. In addition, we also discuss the effect of dislocation types, of applied strain and of the deformation method on the interaction of dislocations and interfaces.

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Dislocation Nucleation on Grain Boundaries: Low Angle Twist and Asymmetric Tilt Boundaries

Cited by 14 publications

References 40 publications

Evaluation of Mechanical Properties and Microstructures of Direct‐Quenched and Direct‐Quenched and Tempered Microalloyed Ultrahigh‐Strength Steels

Evaluation of Mechanical Properties and Microstructures of Direct‐Quenched and Direct‐Quenched and Tempered Microalloyed Ultrahigh‐Strength Steels

Atomistic Insights on the Wear/Friction Behavior of Nanocrystalline Ferrite During Nanoscratching as Revealed by Molecular Dynamics

Interaction of Dislocations and Interfaces in Crystalline Heterostructures: A Review of Atomistic Studies

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