The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform
D H Lassila - One of the best experts on this subject based on the ideXlab platform.
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shock induced deformation twinning and Omega Transformation in tantalum and tantalum tungsten alloys
Acta Materialia, 2000Co-Authors: L M Hsiung, D H LassilaAbstract:Abstract Effects of high strain-rate and high plastic-strain deformation on the development of deformation substructures in tantalum and tantalum–tungsten alloys (Ta–2.5 wt.% W and Ta–10 wt.% W) shocked at 15 and 45 GPa have been investigated. In addition to dislocation cells/walls, and {112} -type deformation twinning, a shock-induced Omega phase (hexagonal) is also found within polycrystalline tantalum shocked at 45 GPa. The orientation relationships between the Omega phase and parent (bcc) matrix are {10 1 0} h ‖{211} b ,[0001] h ‖ b and 2 10> h ‖ 1 1> b . The lattice parameters of Omega phase are a h ≈ 2 a b =0.468 nm and c h ≈( 3 /2)a b =0.286 nm (c h /a h =0.611). Since both deformation twinning and Omega Transformation occur preferably in the {211}b planes with high resolved shear stresses, it is suggested that both can be considered as alternative paths for shear Transformations in shock-deformed tantalum. A greater volume fraction of twin and Omega phase formed in Ta–W than in pure Ta reveals that shock-induced shear Transformations can be promoted by solid solution alloying. While deformation twinning is resulted from 1/6 1 1 > homogeneous shear in consecutive {211} planes, Omega Transformation can be attributed to the 1/12 1 1 >, 1/3 1 1 > and 1/12 1 1 > inhomogeneous shear in consecutive {211} planes. Dislocation mechanisms for shock-induced twinning and Omega Transformation are proposed and critically discussed.
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Shock-induced deformation twinning and Omega Transformation in tantalum and tantalum–tungsten alloys
Acta Materialia, 2000Co-Authors: L M Hsiung, D H LassilaAbstract:Abstract Effects of high strain-rate and high plastic-strain deformation on the development of deformation substructures in tantalum and tantalum–tungsten alloys (Ta–2.5 wt.% W and Ta–10 wt.% W) shocked at 15 and 45 GPa have been investigated. In addition to dislocation cells/walls, and {112} -type deformation twinning, a shock-induced Omega phase (hexagonal) is also found within polycrystalline tantalum shocked at 45 GPa. The orientation relationships between the Omega phase and parent (bcc) matrix are {10 1 0} h ‖{211} b ,[0001] h ‖ b and 2 10> h ‖ 1 1> b . The lattice parameters of Omega phase are a h ≈ 2 a b =0.468 nm and c h ≈( 3 /2)a b =0.286 nm (c h /a h =0.611). Since both deformation twinning and Omega Transformation occur preferably in the {211}b planes with high resolved shear stresses, it is suggested that both can be considered as alternative paths for shear Transformations in shock-deformed tantalum. A greater volume fraction of twin and Omega phase formed in Ta–W than in pure Ta reveals that shock-induced shear Transformations can be promoted by solid solution alloying. While deformation twinning is resulted from 1/6 1 1 > homogeneous shear in consecutive {211} planes, Omega Transformation can be attributed to the 1/12 1 1 >, 1/3 1 1 > and 1/12 1 1 > inhomogeneous shear in consecutive {211} planes. Dislocation mechanisms for shock-induced twinning and Omega Transformation are proposed and critically discussed.
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Shock-induced displacive Transformations in tantalum and tantalum-tungsten alloys
Scripta Materialia, 1998Co-Authors: L M Hsiung, D H LassilaAbstract:A recent investigation on the deformation substructure of shocked tantalum by transmission electron microscopy (TEM) has for the first-time revealed that a displacive Omega Transformation can also take place in tantalum (a group V transition metal) under a high shock peak pressure (45 GPa). Plate- or lath-like {Omega} phase ({Omega}{prime} hereafter) has been observed within shocked tantalum, which is considered to be unusual since tantalum has a bcc structure and exhibits no equilibrium phase Transformation up to its melting temperature at ambient pressure. The occurrence of displacive Omega Transformation within shocked tantalum is of great interest because it provides not only an effective strengthening mechanism for tantalum and tantalum alloys but also an opportunity to study and understand the mechanisms of displacive {beta} {yields} {Omega}{prime} transition induced by high strain-rate deformation. Results from the investigation of displacive Omega Transformation in tantalum and tantalum-tungsten alloy are reported and discussed here.
L M Hsiung - One of the best experts on this subject based on the ideXlab platform.
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shock induced deformation twinning and Omega Transformation in tantalum and tantalum tungsten alloys
Acta Materialia, 2000Co-Authors: L M Hsiung, D H LassilaAbstract:Abstract Effects of high strain-rate and high plastic-strain deformation on the development of deformation substructures in tantalum and tantalum–tungsten alloys (Ta–2.5 wt.% W and Ta–10 wt.% W) shocked at 15 and 45 GPa have been investigated. In addition to dislocation cells/walls, and {112} -type deformation twinning, a shock-induced Omega phase (hexagonal) is also found within polycrystalline tantalum shocked at 45 GPa. The orientation relationships between the Omega phase and parent (bcc) matrix are {10 1 0} h ‖{211} b ,[0001] h ‖ b and 2 10> h ‖ 1 1> b . The lattice parameters of Omega phase are a h ≈ 2 a b =0.468 nm and c h ≈( 3 /2)a b =0.286 nm (c h /a h =0.611). Since both deformation twinning and Omega Transformation occur preferably in the {211}b planes with high resolved shear stresses, it is suggested that both can be considered as alternative paths for shear Transformations in shock-deformed tantalum. A greater volume fraction of twin and Omega phase formed in Ta–W than in pure Ta reveals that shock-induced shear Transformations can be promoted by solid solution alloying. While deformation twinning is resulted from 1/6 1 1 > homogeneous shear in consecutive {211} planes, Omega Transformation can be attributed to the 1/12 1 1 >, 1/3 1 1 > and 1/12 1 1 > inhomogeneous shear in consecutive {211} planes. Dislocation mechanisms for shock-induced twinning and Omega Transformation are proposed and critically discussed.
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Shock-induced deformation twinning and Omega Transformation in tantalum and tantalum–tungsten alloys
Acta Materialia, 2000Co-Authors: L M Hsiung, D H LassilaAbstract:Abstract Effects of high strain-rate and high plastic-strain deformation on the development of deformation substructures in tantalum and tantalum–tungsten alloys (Ta–2.5 wt.% W and Ta–10 wt.% W) shocked at 15 and 45 GPa have been investigated. In addition to dislocation cells/walls, and {112} -type deformation twinning, a shock-induced Omega phase (hexagonal) is also found within polycrystalline tantalum shocked at 45 GPa. The orientation relationships between the Omega phase and parent (bcc) matrix are {10 1 0} h ‖{211} b ,[0001] h ‖ b and 2 10> h ‖ 1 1> b . The lattice parameters of Omega phase are a h ≈ 2 a b =0.468 nm and c h ≈( 3 /2)a b =0.286 nm (c h /a h =0.611). Since both deformation twinning and Omega Transformation occur preferably in the {211}b planes with high resolved shear stresses, it is suggested that both can be considered as alternative paths for shear Transformations in shock-deformed tantalum. A greater volume fraction of twin and Omega phase formed in Ta–W than in pure Ta reveals that shock-induced shear Transformations can be promoted by solid solution alloying. While deformation twinning is resulted from 1/6 1 1 > homogeneous shear in consecutive {211} planes, Omega Transformation can be attributed to the 1/12 1 1 >, 1/3 1 1 > and 1/12 1 1 > inhomogeneous shear in consecutive {211} planes. Dislocation mechanisms for shock-induced twinning and Omega Transformation are proposed and critically discussed.
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Shock-induced displacive Transformations in tantalum and tantalum-tungsten alloys
Scripta Materialia, 1998Co-Authors: L M Hsiung, D H LassilaAbstract:A recent investigation on the deformation substructure of shocked tantalum by transmission electron microscopy (TEM) has for the first-time revealed that a displacive Omega Transformation can also take place in tantalum (a group V transition metal) under a high shock peak pressure (45 GPa). Plate- or lath-like {Omega} phase ({Omega}{prime} hereafter) has been observed within shocked tantalum, which is considered to be unusual since tantalum has a bcc structure and exhibits no equilibrium phase Transformation up to its melting temperature at ambient pressure. The occurrence of displacive Omega Transformation within shocked tantalum is of great interest because it provides not only an effective strengthening mechanism for tantalum and tantalum alloys but also an opportunity to study and understand the mechanisms of displacive {beta} {yields} {Omega}{prime} transition induced by high strain-rate deformation. Results from the investigation of displacive Omega Transformation in tantalum and tantalum-tungsten alloy are reported and discussed here.
R. Banerjee - One of the best experts on this subject based on the ideXlab platform.
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Deformation Induced Hierarchical Twinning Coupled with Omega Transformation in a Metastable β-Ti Alloy
Scientific Reports, 2019Co-Authors: S. A. Mantri, D. Choudhuri, T. Alam, B. Gwalani, F. Prima, R. BanerjeeAbstract:Hierarchical twinning, at multiple length scales, was noted in a metastable body-centered cubic (bcc) β-titanium alloy on tensile deformation. Site-specific characterization within the deformation bands, carried out using EBSD and TEM, revealed {332} type primary bcc twins, containing different variants of secondary and tertiary twins, as well as the formation of stress-induced martensite (α”). Within the primary {332} type twin, “destruction” of the prior quenched-in athermal ω phase was observed, while a stress-induced ω phase reforms within the tertiary twins, revealing the intricate nature of coupling between deformation twinning and displacive ω Transformation.
S. A. Mantri - One of the best experts on this subject based on the ideXlab platform.
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Deformation Induced Hierarchical Twinning Coupled with Omega Transformation in a Metastable β-Ti Alloy
Scientific Reports, 2019Co-Authors: S. A. Mantri, D. Choudhuri, T. Alam, B. Gwalani, F. Prima, R. BanerjeeAbstract:Hierarchical twinning, at multiple length scales, was noted in a metastable body-centered cubic (bcc) β-titanium alloy on tensile deformation. Site-specific characterization within the deformation bands, carried out using EBSD and TEM, revealed {332} type primary bcc twins, containing different variants of secondary and tertiary twins, as well as the formation of stress-induced martensite (α”). Within the primary {332} type twin, “destruction” of the prior quenched-in athermal ω phase was observed, while a stress-induced ω phase reforms within the tertiary twins, revealing the intricate nature of coupling between deformation twinning and displacive ω Transformation.
D. Choudhuri - One of the best experts on this subject based on the ideXlab platform.
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Deformation Induced Hierarchical Twinning Coupled with Omega Transformation in a Metastable β-Ti Alloy
Scientific Reports, 2019Co-Authors: S. A. Mantri, D. Choudhuri, T. Alam, B. Gwalani, F. Prima, R. BanerjeeAbstract:Hierarchical twinning, at multiple length scales, was noted in a metastable body-centered cubic (bcc) β-titanium alloy on tensile deformation. Site-specific characterization within the deformation bands, carried out using EBSD and TEM, revealed {332} type primary bcc twins, containing different variants of secondary and tertiary twins, as well as the formation of stress-induced martensite (α”). Within the primary {332} type twin, “destruction” of the prior quenched-in athermal ω phase was observed, while a stress-induced ω phase reforms within the tertiary twins, revealing the intricate nature of coupling between deformation twinning and displacive ω Transformation.
