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Sven C. Vogel - One of the best experts on this subject based on the ideXlab platform.
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Quantitative prediction of transformation Texture in steel by Double Kurdjumov-Sachs relation
IOP Conference Series: Materials Science and Engineering, 2015Co-Authors: Toshiro Tomida, Masayuki Wakita, Sven C. Vogel, Hugo Ricardo Zschommler SandimAbstract:The transformation Texture prediction by so-called double K-S relation is described. Various types of transformation Textures such as the one in hot-rolled steel sheets and those of Texture Memory in hot-rolled steel and cold-rolled pure iron have been reported to be able to be quantitatively predicted by this variant selection rule. Recently such an experimental investigation has been extended to the Texture Memory in ECAP-processed pure iron. Although the type of Texture as well as the symmetry of samples in ECAP iron is very different from the previous materials, the investigation has clearly indicated that the double K-S relation should indeed be the mechanism governing variant selection on the phase transformation in iron and steel.
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Memory effects of transformation Textures in steel and its prediction by the double Kurdjumov–Sachs relation
Acta Materialia, 2013Co-Authors: Toshiro Tomida, Masayuki Wakita, Masanori Yasuyama, S. Sugaya, Y. Tomota, Sven C. VogelAbstract:Abstract The phenomenon that the transformation Texture near the initial Texture reproduces after the phase transformation cycle such as ferrite (α, body-centered cubic) → austenite (γ, face-centered cubic) → α is called a Texture Memory. In this study, the Texture change in a 0.1% C–1% Mn hot-rolled steel sheet during the α → γ → α transformation cycle was studied via neutron diffraction and the transformation Texture prediction based on a variant selection rule that we call the double Kurdjumov–Sachs (K–S) relation. The Texture change observed by neutron diffraction, which clearly showed the Texture Memory, could be quantitatively reproduced by the proposed variant selection rule adopted into the calculation method based on the spherical harmonics expansion of orientation distribution functions. Therefore, it is most likely that the Texture Memory in steel is caused by the preferential selection of those K–S variants that reduce the interfacial energy between a precipitate and two adjoining parent phase grains at the same time, which we call the double K–S relation.
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in situ observation of Texture evolution during α β and β α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: Sven C. Vogel, I Lonardelli, Nathalie Gey, H R Wenk, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
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In situ observation of Texture evolution during α → β and β → α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: I Lonardelli, Hans-rudolf Wenk, Sven C. Vogel, Nathalie Gey, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
I Lonardelli - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of Texture evolution during α β and β α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: Sven C. Vogel, I Lonardelli, Nathalie Gey, H R Wenk, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
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In situ observation of Texture evolution during α → β and β → α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: I Lonardelli, Hans-rudolf Wenk, Sven C. Vogel, Nathalie Gey, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
Luca Lutterotti - One of the best experts on this subject based on the ideXlab platform.
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in situ observation of Texture evolution during α β and β α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: Sven C. Vogel, I Lonardelli, Nathalie Gey, H R Wenk, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
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In situ observation of Texture evolution during α → β and β → α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: I Lonardelli, Hans-rudolf Wenk, Sven C. Vogel, Nathalie Gey, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
Marcus Magnor - One of the best experts on this subject based on the ideXlab platform.
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Effective Multi-resolution Rendering and Texture Compression for Captured Volumetric Trees
2006Co-Authors: Christian Linz, Alex Reche, George Drettakis, Marcus MagnorAbstract:Trees can be realistically rendered in synthetic environments by creating volumetric representations from photographs. However, volumetric tree representations created with previous methods are expensive to render due to the high number of primitives, and have very high Texture Memory requirements. We address both shortcomings by presenting an efficient multi-resolution rendering method and an effective Texture compression solution. Our method uses an octree with appropriate Textures at intermediate hierarchy levels and applies an effective pruning strategy. For Texture compression, we adapt a vector quantization approach in a perceptually accurate color space, and modify the codebook generation of the Generalized Lloyd Algorithm to further improve Texture quality. In combination with several hardware acceleration techniques, our approach achieves a reduction in Texture Memory requirements by one order of magnitude; in addition, it is now possible to render tens or even hundreds of captured trees at interactive rates.
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NPH - Effective multi-resolution rendering and Texture compression for captured volumetric trees
New Phytologist, 2006Co-Authors: Christian Linz, George Drettakis, Alex Reche-martinez, Marcus MagnorAbstract:Trees can be realistically rendered in synthetic environments by creating volumetric representations from photographs. However, volumetric tree representations created with previous methods are expensive to render due to the high number of primitives, and have very high Texture Memory requirements. We address both shortcomings by presenting an efficient multi-resolution rendering method and an effective Texture compression solution. Our method uses an octree with appropriate Textures at intermediate hierarchy levels and applies an effective pruning strategy. For Texture compression, we adapt a vector quantization approach in a perceptually accurate color space, and modify the codebook generation of the Generalized Lloyd Algorithm to further improve Texture quality. In combination with several hardware acceleration techniques, our approach achieves a reduction in Texture Memory requirements by one order of magnitude; in addition, it is now possible to render tens or even hundreds of captured trees at interactive rates.
Hans-rudolf Wenk - One of the best experts on this subject based on the ideXlab platform.
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Dauphiné twinning and Texture Memory in polycrystalline quartz. Part 3: Texture Memory during phase transformation
Physics and Chemistry of Minerals, 2009Co-Authors: Hans-rudolf Wenk, N. Barton, M. Bortolotti, S. C. Vogel, M. Voltolini, G. E. Lloyd, G. B. GonzalezAbstract:Samples of quartz-bearing rocks were heated above the α (trigonal)–β (hexagonal) phase transformation of quartz (625–950°C) to explore changes in preferred orientation patterns. Textures were measured both in situ and ex situ with neutron, synchrotron X-ray and electron backscatter diffraction. The trigonal–hexagonal phase transformation does not change the orientation of c - and a -axes, but positive and negative rhombs become equal in the hexagonal β-phase. In naturally deformed quartzites measured by neutron diffraction a perfect Texture Memory was observed, i.e. crystals returned to the same trigonal orientation they started from, with no evidence of twin boundaries. Samples measured by electron back-scattered diffraction on surfaces show considerable twinning and Memory loss after the phase transformation. In experimentally deformed quartz rocks, where twinning was induced mechanically before heating, the orientation Memory is lost. A mechanical model can explain the Memory loss but so far it does not account for the persistence of the Memory in quartzites. Stresses imposed by neighboring grains remain a likely cause of Texture Memory in this mineral with a very high elastic anisotropy. If stresses are imposed experimentally the internal stresses are released during the phase transformation and the material returns to its original state prior to deformation. Similarly, on surfaces there are no tractions and thus Texture Memory is partially lost.
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Dauphiné twinning and Texture Memory in polycrystalline quartz
Physics and Chemistry of Minerals, 2007Co-Authors: Hans-rudolf Wenk, N. Barton, M. Bortolotti, E. Oliver, D. BrownAbstract:Mechanical twinning in polycrystalline quartz was investigated in situ with time-of-flight neutron diffraction and a strain diffractometer. Dauphiné twinning is highly temperature sensitive. It initiates at a macroscopic differential stress of 50–100 MPa and, at 500°C, saturates at 400 MPa. From normalized diffraction intensities the patterns of preferred orientation (or Texture) can be inferred. They indicate a partial reversal of twinning during unloading. The remaining twins impose residual stresses corresponding to elastic strains of 300–400 microstrain. Progressive twinning on loading and reversal during unloading, as well as the temperature dependence, can be reproduced with finite element model simulations.
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Dauphiné twinning and Texture Memory in polycrystalline quartz
Physics and Chemistry of Minerals, 2007Co-Authors: Hans-rudolf Wenk, M. Bortolotti, E. Oliver, Nathan R. Barton, Donald W. BrownAbstract:Mechanical twinning in polycrystalline quartz was investigated in situ with time-of-flight neutron diffraction and a strain diffractometer. Dauphine twinning is highly temperature sensitive. It initiates at a macroscopic differential stress of 50–100 MPa and, at 500°C, saturates at 400 MPa. From normalized diffraction intensities the patterns of preferred orientation (or Texture) can be inferred. They indicate a partial reversal of twinning during unloading. The remaining twins impose residual stresses corresponding to elastic strains of 300–400 microstrain. Progressive twinning on loading and reversal during unloading, as well as the temperature dependence, can be reproduced with finite element model simulations.
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Dauphiné twinning in polycrystalline quartz
Modelling and Simulation in Materials Science and Engineering, 2007Co-Authors: Nathan R. Barton, Hans-rudolf WenkAbstract:A recently developed crystal based continuum model for twinning and phase transformations is successfully applied to Dauphine twinning and the α (trigonal) ↔ β (hexagonal) phase transformation in quartz. Both finite element and uniform deformation simulations are performed of quartz polycrystals and several experimentally observed phenomena are qualitatively reproduced. Results are given for mechanically induced twinning and Texture Memory during phase transformation. The results highlight the importance of local stress variations due to grain interactions. Due to the form of the driving force, twinning is particularly sensitive to local stress variations.
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In situ observation of Texture evolution during α → β and β → α phase transformations in titanium alloys investigated by neutron diffraction
Acta Materialia, 2007Co-Authors: I Lonardelli, Hans-rudolf Wenk, Sven C. Vogel, Nathalie Gey, Michel Humbert, Luca LutterottiAbstract:Abstract Texture changes during recrystallization and the α–β–α phase transformation in two titanium alloys were investigated in situ by time-of-flight neutron diffraction by heating in a vacuum furnace to 950 °C. In commercially pure titanium, a strong Texture Memory effect is observed. This effect is a direct consequence of an orientation-selective α → β transformation, favoring new orientations produced during nucleation and grain growth. The β–α transformation favors β orientations with minimal misorientations, resulting in a strong final α Texture that emphasizes the grain growth component. In Ti–6Al–4V, the Texture Memory effect is less pronounced. The high-temperature β Texture is obtained by growth of pre-existing β nuclei. In a similar way, during cooling, the growth of α domains is controlled by high-temperature α orientations inherited from the β grains with Burgers orientation relation.
