The Experts below are selected from a list of 2010 Experts worldwide ranked by ideXlab platform
Arthur J Freeman - One of the best experts on this subject based on the ideXlab platform.
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dislocation structure phase stability and yield stress behavior of l12 intermetallics ir3x x ti zr hf v nb ta
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2005Co-Authors: Oleg Y. Kontsevoi, A. F. Maksyutov, K. Yu. Khromov, Yu N Gornostyrev, Arthur J FreemanAbstract:The structure and mobility of Superdislocations in Ir3X (X = Ti, Zr, Hf, V, Nb, Ta) with L12 structure were investigated in the framework of the modified Peierls-Nabarro (PN) model with first-principles generalized stacking fault energetics calculated using the all-electron full-potential linearized augmented plane wave method (FLAPW). Superlattice intrinsic stacking fault (SISF)-bound Superdislocations (Kear splitting scheme) are strongly preferred energetically in Ir3V, Ir3Nb, and Ir3Ta, whereas antiphase boundary (APB)-bound Superdislocations (Shockley splitting scheme) are predicted in Ir3Ti, Ir3Zr, and Ir3Hf. Because APB-bound Superdislocations are considered responsible for the yield stress anomaly, our results predict that positive yield stress temperature dependence could only be expected in Ir3Ti, Ir3Zr, and Ir3Hf, and a negative one in Ir3V, Ir3Nb, and Ir3Ta. The connection of the mechanical behavior of the Ir3X alloys with the L12 → D019 structural instability is established and the electronic origins of this instability are analyzed.
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Superdislocation core structure in l12 ni3al ni3ge and fe3ge peierls nabarro analysis starting from ab initio gsf energetics calculations
Acta Materialia, 2002Co-Authors: Oleg N. Mryasov, Yu N Gornostyrev, M. Van Schilfgaarde, Arthur J FreemanAbstract:Superdislocation core structures in L1 2 Ni3Ge, Fe3Ge and Ni3Al were determined on the basis of ab-initio generalized stacking fault (GSF) energetics calculations. Superdislocation dissociation schemes, partials separation and core widths were calculated within the modified Peierls–Nabarro (PN) model with ab-initio GSF parameterization. Calculated Superdislocation core structure parameters were found to be in agreement with available experimental data. The Superdislocation core with type I (fourfold) dissociation was found to be unstable in Fe 3Ge but stable and energetically preferred in Ni3Ge and Ni3Al. These results allows us to suggest a mechanism for the octahedral glide being inactive in Fe 3Ge which is found to be different in several aspects with those discussed so far in the literature. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd.
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Superdislocation core structure in L12 Ni3Al, Ni3Ge and Fe3Ge: Peierls–Nabarro analysis starting from ab-initio GSF energetics calculations
Acta Materialia, 2002Co-Authors: Oleg N. Mryasov, Yu N Gornostyrev, M. Van Schilfgaarde, Arthur J FreemanAbstract:Superdislocation core structures in L1 2 Ni3Ge, Fe3Ge and Ni3Al were determined on the basis of ab-initio generalized stacking fault (GSF) energetics calculations. Superdislocation dissociation schemes, partials separation and core widths were calculated within the modified Peierls–Nabarro (PN) model with ab-initio GSF parameterization. Calculated Superdislocation core structure parameters were found to be in agreement with available experimental data. The Superdislocation core with type I (fourfold) dissociation was found to be unstable in Fe 3Ge but stable and energetically preferred in Ni3Ge and Ni3Al. These results allows us to suggest a mechanism for the octahedral glide being inactive in Fe 3Ge which is found to be different in several aspects with those discussed so far in the literature. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd.
L I Yakovenkova - One of the best experts on this subject based on the ideXlab platform.
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CORE STRUCTURE OF SuperdislocationS AND DESTRUCTION OF THE DISLOCATION BARRIERS AFTER HIGH-TEMPERATURE DEFORMATION OF Ti3Al
2015Co-Authors: L I Yakovenkova, L E KarkinaAbstract:Abstract. An electron microscopic analysis of the dislocation structure of the Ti3Al intermetallic after high-temperature deformation is performed. It is found that the microstructure of the samples deformed at T = 1073-1173 K contains mobile a, 2c+a and other c component Superdislocations. Experimental data are discussed considering results of the computer simulation of the Superdislocation core structure in Ti3Al
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Dislocation core structure and deformation behavior of Ti3Al
Modelling and Simulation in Materials Science and Engineering, 2012Co-Authors: L E Karkina, L I YakovenkovaAbstract:Using molecular dynamics simulations with the embedded atom method we calculate the core structure of a Superdislocations in prism and basal planes and 2c?+?a Superdislocations in pyramid planes. An analysis of the structure of the cores showed that the core is planar in the prismatic plane and nonplanar for screw superpartial dislocations in the basal plane. It is shown that the glissile 2c?+?a Superdislocations have higher energy than the configurations of dislocation barriers. The influence of the core structure of Superdislocations on the orientation dependence of the deformation behavior of Ti3Al is discussed.
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High-temperature deformation and specific features of dislocation structure of Ti3Al
Bulletin of the Russian Academy of Sciences: Physics, 2009Co-Authors: L I Yakovenkova, L. E. Kar’kina, O. A. ElkinaAbstract:The transmission electron microscopy was used to examine the dislocation structure of intermetallic Ti3Al after deformation at temperatures T = 1073–1273 K. It is established that its microstructure contains mobile 2c + a and Superdislocations. Possible models describing the destruction of barriers associated with 2c + a Superdislocations in pyramidal planes are discussed using the results of computer simulation of the Superdislocation core structure in Ti3Al.
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High-temperature deformation and specific features of dislocation structure of Ti_3Al
Bulletin of the Russian Academy of Sciences: Physics, 2009Co-Authors: L I Yakovenkova, L. E. Kar’kina, O. A. ElkinaAbstract:The transmission electron microscopy was used to examine the dislocation structure of intermetallic Ti_3Al after deformation at temperatures T = 1073–1273 K. It is established that its microstructure contains mobile 2 c + a and Superdislocations. Possible models describing the destruction of barriers associated with 2 c + a Superdislocations in pyramidal planes are discussed using the results of computer simulation of the Superdislocation core structure in Ti_3Al.
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Dislocation structure of intermetallic Ti_3Al subjected to high-temperature deformation
Physics of the Solid State, 2008Co-Authors: L. E. Kar’kina, O. A. Elkina, L I YakovenkovaAbstract:Transmission electron microscopy was used to examine the dislocation structure of intermetallic Ti_3Al subjected to deformation at tempertures T = 1073–1273 K. The microstructure of samples subjected to high-temperature deformation is established to contain mobile Superdislocations of a and 2 c + a types, and single dislocations with Burgers vector [0001] are also observed on the prismatic planes. Possible models of destruction of barriers associated with 2 c + a Superdislocations on the pyramidal planes are discussed using the results of computer simulations of the structure of a Superdislocation core in in Ti_3Al.
Yutaka Koizumi - One of the best experts on this subject based on the ideXlab platform.
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New configuration of a [001] Superdislocation formed during high-temperature creep in the γ′ phase of a single-crystal superalloy TMS-138
Journal of Materials Research, 2006Co-Authors: J.x. Zhang, Hiroshi Harada, Yutaka KoizumiAbstract:A new configuration of a Superdislocation in the γ′ phase of a fourth-generation single-crystal TMS-138 superalloy was found after creep rupture in a [001] tensile test at 1150 °C and 137 MPa. The segments of the Superdislocation lie in four directions, i.e., [110], [1 1 0], [100], and [010], strictly on a (001) plane with a Burgers vector b = [001]. This Superdislocation is pure edge in character and does not dissociate into superpartials. Microstructural evidence shows that this kind of Superdislocation is formed by combination of two interfacial dislocations with different Burgers vectors, i.e., 1/2[011] + 1/2[0 1 1] → [001].
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New configuration of a [001] Superdislocation formed during high-temperature creep in the γ′ phase of a single-crystal superalloy TMS-138
Journal of Materials Research, 2006Co-Authors: J.x. Zhang, Hiroshi Harada, Yutaka KoizumiAbstract:A new configuration of a Superdislocation in the γ′ phase of a fourth-generation single-crystal TMS-138 superalloy was found after creep rupture in a [001] tensile test at 1150 °C and 137 MPa. The segments of the Superdislocation lie in four directions, i.e., [110], $$[1\overline{1}0]$$ [ 1 1 ¯ 0 ] , [100], and [010], strictly on a (001) plane with a Burgers vector b = [001]. This Superdislocation is pure edge in character and does not dissociate into superpartials. Microstructural evidence shows that this kind of Superdislocation is formed by combination of two interfacial dislocations with different Burgers vectors, i.e., 1/2[011] + 1/2 $$[0\overline{1}1]$$ [ 0 1 ¯ 1 ] → [001].
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Slip geometry of dislocations related to cutting of the γ′ phase in a new generation single-crystal superalloy
Acta Materialia, 2003Co-Authors: J.x. Zhang, Yutaka Koizumi, Takao Murakumo, Toshiharu Kobayashi, Hirofumi HaradaAbstract:Abstract The Superdislocations in the γ′ phase of a fourth-generation single-crystal TMS-138 superalloy have been characterized after creep rupture at a stress of 137 MPa under different temperatures. The number of slip dislocations increases with the increase of creep temperatures from 1100 to 1150 °C. The dominant cutting mode of the γ′ phase is dislocation pairs coupled by an antiphase boundary (APB). The popular Superdislocations in the γ′ phase show screw character with Burgers vectors or . Also, observed in the γ′ phase are 60° or screw Superdislocations in either [1 1 0] or [ 1 1 0 ] directions, and [0 0 1] edge Superdislocations. Stacking faults are seen from the dissociation of Superdislocations. These Superdislocations are related to the damage of the rafted structure in the superalloy.
J.x. Zhang - One of the best experts on this subject based on the ideXlab platform.
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New configuration of a [001] Superdislocation formed during high-temperature creep in the γ′ phase of a single-crystal superalloy TMS-138
Journal of Materials Research, 2006Co-Authors: J.x. Zhang, Hiroshi Harada, Yutaka KoizumiAbstract:A new configuration of a Superdislocation in the γ′ phase of a fourth-generation single-crystal TMS-138 superalloy was found after creep rupture in a [001] tensile test at 1150 °C and 137 MPa. The segments of the Superdislocation lie in four directions, i.e., [110], [1 1 0], [100], and [010], strictly on a (001) plane with a Burgers vector b = [001]. This Superdislocation is pure edge in character and does not dissociate into superpartials. Microstructural evidence shows that this kind of Superdislocation is formed by combination of two interfacial dislocations with different Burgers vectors, i.e., 1/2[011] + 1/2[0 1 1] → [001].
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New configuration of a [001] Superdislocation formed during high-temperature creep in the γ′ phase of a single-crystal superalloy TMS-138
Journal of Materials Research, 2006Co-Authors: J.x. Zhang, Hiroshi Harada, Yutaka KoizumiAbstract:A new configuration of a Superdislocation in the γ′ phase of a fourth-generation single-crystal TMS-138 superalloy was found after creep rupture in a [001] tensile test at 1150 °C and 137 MPa. The segments of the Superdislocation lie in four directions, i.e., [110], $$[1\overline{1}0]$$ [ 1 1 ¯ 0 ] , [100], and [010], strictly on a (001) plane with a Burgers vector b = [001]. This Superdislocation is pure edge in character and does not dissociate into superpartials. Microstructural evidence shows that this kind of Superdislocation is formed by combination of two interfacial dislocations with different Burgers vectors, i.e., 1/2[011] + 1/2 $$[0\overline{1}1]$$ [ 0 1 ¯ 1 ] → [001].
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Slip geometry of dislocations related to cutting of the γ′ phase in a new generation single-crystal superalloy
Acta Materialia, 2003Co-Authors: J.x. Zhang, Yutaka Koizumi, Takao Murakumo, Toshiharu Kobayashi, Hirofumi HaradaAbstract:Abstract The Superdislocations in the γ′ phase of a fourth-generation single-crystal TMS-138 superalloy have been characterized after creep rupture at a stress of 137 MPa under different temperatures. The number of slip dislocations increases with the increase of creep temperatures from 1100 to 1150 °C. The dominant cutting mode of the γ′ phase is dislocation pairs coupled by an antiphase boundary (APB). The popular Superdislocations in the γ′ phase show screw character with Burgers vectors or . Also, observed in the γ′ phase are 60° or screw Superdislocations in either [1 1 0] or [ 1 1 0 ] directions, and [0 0 1] edge Superdislocations. Stacking faults are seen from the dissociation of Superdislocations. These Superdislocations are related to the damage of the rafted structure in the superalloy.
Yu N Gornostyrev - One of the best experts on this subject based on the ideXlab platform.
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Dislocation structure, phase stability, and yield stress behavior of L1_2 intermetallics: Ir_3X (X = Ti, Zr, Hf, V, Nb, Ta)
Metallurgical and Materials Transactions A, 2005Co-Authors: Oleg Y. Kontsevoi, A. F. Maksyutov, A J Freeman, Yu N Gornostyrev, K. Yu. KhromovAbstract:The structure and mobility of Superdislocations in Ir_3X (X = Ti, Zr, Hf, V, Nb, Ta) with L1_2 structure were investigated in the framework of the modified Peierls-Nabarro (PN) model with first-principles generalized stacking fault energetics calculated using the all-electron full-potential linearized augmented plane wave method (FLAPW). Superlattice intrinsic stacking fault (SISF)-bound Superdislocations (Kear splitting scheme) are strongly preferred energetically in Ir_3V, Ir_3Nb, and Ir_3Ta, whereas antiphase boundary (APB)-bound Superdislocations (Shockley splitting scheme) are predicted in Ir_3Ti, Ir_3Zr, and Ir_3Hf. Because APB-bound Superdislocations are considered responsible for the yield stress anomaly, our results predict that positive yield stress temperature dependence could only be expected in Ir_3Ti, Ir_3Zr, and Ir_3Hf, and a negative one in Ir_3V, Ir_3Nb, and Ir_3Ta. The connection of the mechanical behavior of the Ir_3X alloys with the L1_2 → D0_19 structural instability is established and the electronic origins of this instability are analyzed.
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dislocation structure phase stability and yield stress behavior of l12 intermetallics ir3x x ti zr hf v nb ta
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2005Co-Authors: Oleg Y. Kontsevoi, A. F. Maksyutov, K. Yu. Khromov, Yu N Gornostyrev, Arthur J FreemanAbstract:The structure and mobility of Superdislocations in Ir3X (X = Ti, Zr, Hf, V, Nb, Ta) with L12 structure were investigated in the framework of the modified Peierls-Nabarro (PN) model with first-principles generalized stacking fault energetics calculated using the all-electron full-potential linearized augmented plane wave method (FLAPW). Superlattice intrinsic stacking fault (SISF)-bound Superdislocations (Kear splitting scheme) are strongly preferred energetically in Ir3V, Ir3Nb, and Ir3Ta, whereas antiphase boundary (APB)-bound Superdislocations (Shockley splitting scheme) are predicted in Ir3Ti, Ir3Zr, and Ir3Hf. Because APB-bound Superdislocations are considered responsible for the yield stress anomaly, our results predict that positive yield stress temperature dependence could only be expected in Ir3Ti, Ir3Zr, and Ir3Hf, and a negative one in Ir3V, Ir3Nb, and Ir3Ta. The connection of the mechanical behavior of the Ir3X alloys with the L12 → D019 structural instability is established and the electronic origins of this instability are analyzed.
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Superdislocation core structure in l12 ni3al ni3ge and fe3ge peierls nabarro analysis starting from ab initio gsf energetics calculations
Acta Materialia, 2002Co-Authors: Oleg N. Mryasov, Yu N Gornostyrev, M. Van Schilfgaarde, Arthur J FreemanAbstract:Superdislocation core structures in L1 2 Ni3Ge, Fe3Ge and Ni3Al were determined on the basis of ab-initio generalized stacking fault (GSF) energetics calculations. Superdislocation dissociation schemes, partials separation and core widths were calculated within the modified Peierls–Nabarro (PN) model with ab-initio GSF parameterization. Calculated Superdislocation core structure parameters were found to be in agreement with available experimental data. The Superdislocation core with type I (fourfold) dissociation was found to be unstable in Fe 3Ge but stable and energetically preferred in Ni3Ge and Ni3Al. These results allows us to suggest a mechanism for the octahedral glide being inactive in Fe 3Ge which is found to be different in several aspects with those discussed so far in the literature. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd.
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Superdislocation core structure in L12 Ni3Al, Ni3Ge and Fe3Ge: Peierls–Nabarro analysis starting from ab-initio GSF energetics calculations
Acta Materialia, 2002Co-Authors: Oleg N. Mryasov, Yu N Gornostyrev, M. Van Schilfgaarde, Arthur J FreemanAbstract:Superdislocation core structures in L1 2 Ni3Ge, Fe3Ge and Ni3Al were determined on the basis of ab-initio generalized stacking fault (GSF) energetics calculations. Superdislocation dissociation schemes, partials separation and core widths were calculated within the modified Peierls–Nabarro (PN) model with ab-initio GSF parameterization. Calculated Superdislocation core structure parameters were found to be in agreement with available experimental data. The Superdislocation core with type I (fourfold) dissociation was found to be unstable in Fe 3Ge but stable and energetically preferred in Ni3Ge and Ni3Al. These results allows us to suggest a mechanism for the octahedral glide being inactive in Fe 3Ge which is found to be different in several aspects with those discussed so far in the literature. 2002 Acta Materialia Inc. Published by Elsevier Science Ltd.