The Experts below are selected from a list of 31347 Experts worldwide ranked by ideXlab platform
Xavier Maeder - One of the best experts on this subject based on the ideXlab platform.
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on the nucleation and growth of 112 2 twin in commercial purity titanium in situ investigation of the Local Stress Field and dislocation density distribution
Acta Materialia, 2016Co-Authors: Yi Guo, Jakob Schwiedrzik, J. Michler, Xavier MaederAbstract:Compression testing was conducted on a micro-pillar consisting of a soft-hard grain pair. A {112¯2} contraction twin variant nucleated at the edge of the hard grain and elongated progressively into the pillar towards the grain boundary. High angular resolution EBSD scans were performed in situ during the compression testing in order to characterize the elastic strain Field and dislocation density distribution at the twin-parent interface during the twin growth. The Local/global shear Stress ratio on the active twin variant increased from ∼1.6, before macroscopic yielding, to ∼4.2 at peak load, and the rate of increase is inversely proportional to the macroscopic strain level. While the active twin variant does not have the highest global shear Stress, it does experience a higher Local shear compared to other twin variants, which may contribute to its nucleation. The elongation of the active twin variant involves a competition between Local shear Stress and dislocation density in front of the twin tip. This could lead to a discontinuous elongation process and stop twin from reaching grain boundary—a phenomenon frequently observed from large grain materials. After removal of the external loading, twinning shear partially reversed sign along the twin-parent interface, indicating a tendency to de-twin.
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On the nucleation and growth of {112¯2} twin in commercial purity titanium: In situ investigation of the Local Stress Field and dislocation density distribution
Acta Materialia, 2016Co-Authors: Yi Guo, Jakob Schwiedrzik, J. Michler, Xavier MaederAbstract:Compression testing was conducted on a micro-pillar consisting of a soft-hard grain pair. A {112¯2} contraction twin variant nucleated at the edge of the hard grain and elongated progressively into the pillar towards the grain boundary. High angular resolution EBSD scans were performed in situ during the compression testing in order to characterize the elastic strain Field and dislocation density distribution at the twin-parent interface during the twin growth. The Local/global shear Stress ratio on the active twin variant increased from ∼1.6, before macroscopic yielding, to ∼4.2 at peak load, and the rate of increase is inversely proportional to the macroscopic strain level. While the active twin variant does not have the highest global shear Stress, it does experience a higher Local shear compared to other twin variants, which may contribute to its nucleation. The elongation of the active twin variant involves a competition between Local shear Stress and dislocation density in front of the twin tip. This could lead to a discontinuous elongation process and stop twin from reaching grain boundary—a phenomenon frequently observed from large grain materials. After removal of the external loading, twinning shear partially reversed sign along the twin-parent interface, indicating a tendency to de-twin.
Yi Guo - One of the best experts on this subject based on the ideXlab platform.
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The development of Local plasticity around void during tensile deformation
2020Co-Authors: Yi Guo, Zong Cui, Britton BenAbstract:Voids can limit the life of engineering components. This motivates us to understand Local plasticity around voids in a nickel base superalloy combining experiments and simulations. Single crystal samples were deformed in tension with in-situ high angular resolution electron back scatter diffraction to probe the heterogeneous Local Stress Field under load; the reference Stress is informed by crystal plasticity finite element simulations. This information is used to understand the activation of plastic deformation around the void. Our investigation indicates that while the resolved shear Stress would indicate slip activity on multiple slip systems, slip is reduced to specific systems due to image forces and forest hardening. This study rationalizes the observed development of plastic deformation around the void, aiding in our understanding of component failure and engineering design
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on the nucleation and growth of 112 2 twin in commercial purity titanium in situ investigation of the Local Stress Field and dislocation density distribution
Acta Materialia, 2016Co-Authors: Yi Guo, Jakob Schwiedrzik, J. Michler, Xavier MaederAbstract:Compression testing was conducted on a micro-pillar consisting of a soft-hard grain pair. A {112¯2} contraction twin variant nucleated at the edge of the hard grain and elongated progressively into the pillar towards the grain boundary. High angular resolution EBSD scans were performed in situ during the compression testing in order to characterize the elastic strain Field and dislocation density distribution at the twin-parent interface during the twin growth. The Local/global shear Stress ratio on the active twin variant increased from ∼1.6, before macroscopic yielding, to ∼4.2 at peak load, and the rate of increase is inversely proportional to the macroscopic strain level. While the active twin variant does not have the highest global shear Stress, it does experience a higher Local shear compared to other twin variants, which may contribute to its nucleation. The elongation of the active twin variant involves a competition between Local shear Stress and dislocation density in front of the twin tip. This could lead to a discontinuous elongation process and stop twin from reaching grain boundary—a phenomenon frequently observed from large grain materials. After removal of the external loading, twinning shear partially reversed sign along the twin-parent interface, indicating a tendency to de-twin.
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On the nucleation and growth of {112¯2} twin in commercial purity titanium: In situ investigation of the Local Stress Field and dislocation density distribution
Acta Materialia, 2016Co-Authors: Yi Guo, Jakob Schwiedrzik, J. Michler, Xavier MaederAbstract:Compression testing was conducted on a micro-pillar consisting of a soft-hard grain pair. A {112¯2} contraction twin variant nucleated at the edge of the hard grain and elongated progressively into the pillar towards the grain boundary. High angular resolution EBSD scans were performed in situ during the compression testing in order to characterize the elastic strain Field and dislocation density distribution at the twin-parent interface during the twin growth. The Local/global shear Stress ratio on the active twin variant increased from ∼1.6, before macroscopic yielding, to ∼4.2 at peak load, and the rate of increase is inversely proportional to the macroscopic strain level. While the active twin variant does not have the highest global shear Stress, it does experience a higher Local shear compared to other twin variants, which may contribute to its nucleation. The elongation of the active twin variant involves a competition between Local shear Stress and dislocation density in front of the twin tip. This could lead to a discontinuous elongation process and stop twin from reaching grain boundary—a phenomenon frequently observed from large grain materials. After removal of the external loading, twinning shear partially reversed sign along the twin-parent interface, indicating a tendency to de-twin.
Fabrizio Marra - One of the best experts on this subject based on the ideXlab platform.
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Low-magnitude earthquakes in Rome: structural interpretation and implications for the Local Stress Field
Geophysical Journal International, 1999Co-Authors: Fabrizio MarraAbstract:On 1995 June 12, a ML = 3.6 earthquake occurred in the Cecchignola area of southern Rome. A detailed structural investigation of this area and an analysis of macroseismic and instrumental data indicate a seismogenic area for the Local low-magnitude seismicity that affects the city of Rome. A peripheral volcanic Field in Cecchignola shows that the Local seismicity could be related to the same volcanotectonics that affects the Colli Albani (Alban Hills) region. Fracture-Field emission is proposed for the emplacement of about 2.5 km3 of lava, which developed a small plateau that was subsequently intruded by the feeder dyke of a large ignimbrite. The geometry of this dyke as well as the faults disrupting the lava Field indicates NE–SW extension. Younger tectonic features show a NW-striking σ3 in the studied area, suggesting that dextral N–S strike-slip displacement generated structures that are not compatible with the Local present-day Stress Field, characterized by a NE-striking σ3. An analysis of focal solutions and the spatial distribution of the 1995 June 12 microearthquake sequence suggests an E–W seismogenic structure whose trend is atypical of the structural setting of the area. The present study identifies surface faulting with the same trend as the focal mechanisms in the epicentral area and suggests that these faults represent an inactive surface expression of the deeper structures. It is also suggested that these structures originated during a different tectonic regime and are presently reactivated at depth by the NE–SW extension. The general NE orientation of the T axes from focal mechanisms for the Colli Albani earthquakes and for the 1995 June 12 Cecchignola event strongly supports a regional interpretation for the present-day Stress Field previously observed only in the Colli Albani area. It is likely that a combination of different tectonic styles during the last 600 kyr is necessary to explain the structural features of the Cecchignola area and of the Central Tyrrhenian Sea margin of Italy in general.
Salvatore Scudero - One of the best experts on this subject based on the ideXlab platform.
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Regional and Local Stress Field orientation inferred from quantitative analyses of extension joints: Case study from southern Italy
Tectonics, 2013Co-Authors: Giorgio De Guidi, Riccardo Caputo, Salvatore ScuderoAbstract:[1] An intense tectonic activity in eastern Sicily and southern Calabria (Italy) is well documented by the differential uplift of Late Quaternary coastlines and by the record of the strong historical earthquakes. The extensional belt that crosses this area is dominated by a well-established WNW-ESE–oriented stretching direction. However, this area is largely lacking of any structural analysis for defining the tectonics at a more Local scale. The analysis of systematic extension joint sets affecting Pleistocene deposits presented in this paper allows to infer the causative tectonic Stress tensor by means of a quantitative inversion technique. Local perturbations of the first-order regional Stress Field are consequently recognized. Such perturbations are interpreted as due to interferences between large active faults and their particular geometrical setting. These results contribute to the understanding of the Quaternary tectonic evolution and the present-day Stress regime.
Jakob Schwiedrzik - One of the best experts on this subject based on the ideXlab platform.
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on the nucleation and growth of 112 2 twin in commercial purity titanium in situ investigation of the Local Stress Field and dislocation density distribution
Acta Materialia, 2016Co-Authors: Yi Guo, Jakob Schwiedrzik, J. Michler, Xavier MaederAbstract:Compression testing was conducted on a micro-pillar consisting of a soft-hard grain pair. A {112¯2} contraction twin variant nucleated at the edge of the hard grain and elongated progressively into the pillar towards the grain boundary. High angular resolution EBSD scans were performed in situ during the compression testing in order to characterize the elastic strain Field and dislocation density distribution at the twin-parent interface during the twin growth. The Local/global shear Stress ratio on the active twin variant increased from ∼1.6, before macroscopic yielding, to ∼4.2 at peak load, and the rate of increase is inversely proportional to the macroscopic strain level. While the active twin variant does not have the highest global shear Stress, it does experience a higher Local shear compared to other twin variants, which may contribute to its nucleation. The elongation of the active twin variant involves a competition between Local shear Stress and dislocation density in front of the twin tip. This could lead to a discontinuous elongation process and stop twin from reaching grain boundary—a phenomenon frequently observed from large grain materials. After removal of the external loading, twinning shear partially reversed sign along the twin-parent interface, indicating a tendency to de-twin.
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On the nucleation and growth of {112¯2} twin in commercial purity titanium: In situ investigation of the Local Stress Field and dislocation density distribution
Acta Materialia, 2016Co-Authors: Yi Guo, Jakob Schwiedrzik, J. Michler, Xavier MaederAbstract:Compression testing was conducted on a micro-pillar consisting of a soft-hard grain pair. A {112¯2} contraction twin variant nucleated at the edge of the hard grain and elongated progressively into the pillar towards the grain boundary. High angular resolution EBSD scans were performed in situ during the compression testing in order to characterize the elastic strain Field and dislocation density distribution at the twin-parent interface during the twin growth. The Local/global shear Stress ratio on the active twin variant increased from ∼1.6, before macroscopic yielding, to ∼4.2 at peak load, and the rate of increase is inversely proportional to the macroscopic strain level. While the active twin variant does not have the highest global shear Stress, it does experience a higher Local shear compared to other twin variants, which may contribute to its nucleation. The elongation of the active twin variant involves a competition between Local shear Stress and dislocation density in front of the twin tip. This could lead to a discontinuous elongation process and stop twin from reaching grain boundary—a phenomenon frequently observed from large grain materials. After removal of the external loading, twinning shear partially reversed sign along the twin-parent interface, indicating a tendency to de-twin.
