The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Sunghak Lee - One of the best experts on this subject based on the ideXlab platform.
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Effects of annealing temperature on microstructures and tensile properties of a single Fcc Phase CoCuMnNi high-entropy alloy
Journal of Alloys and Compounds, 2020Co-Authors: Dong Geun Kim, Jeong Min Park, Won Mi Choi, Hyoung Seop Kim, Byeong-joo Lee, Seok Su Sohn, Sunghak LeeAbstract:Abstract Copper (Cu) acts as a strong face-centered cubic (Fcc) stabilizer as well as an effective element lowering the melting point in Fcc-structured high-entropy alloy (HEA) systems. The addition of Cu can reduce the alloy processing temperature; however, there are no studies on the formation of single Fcc Phase in Cu-added HEAs yet. In this study, a Co10Cu20Mn30Ni40 (at.%) HEA was designed by a thermodynamic calculation using a CALPHAD approach by a software Thermo-Calc 3.0, and effects of annealing temperature on microstructures and room- and cryogenic-temperature tensile properties were investigated. The calculation data showed a very wide region of single Fcc Phase (532–1073 °C), which was confirmed from the existence of stable single Fcc Phase at the annealing temperature of 600 °C. The specimen annealed at 600 °C presented the fully-recrystallized Fcc Phase and the refined grain size of 2.8 μm. As the annealing temperature decreased, thus, the strengths increased while the elongation decreased. In addition, both strength and elongation were improved significantly with decreasing the tensile test temperatures from 298 to 77 K, and the major deformation mechanism was changed from a dislocation slip to a deformation twinning, as confirmed from the specimen annealed at 700 and 900 °C. The present study on grain refinement resulting from the low-temperature annealing would suggest a good method for improving cryogenic mechanical properties of single–Fcc–based HEAs.
C. Suryanarayana - One of the best experts on this subject based on the ideXlab platform.
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Mechanically induced Fcc Phase formation in nanocrystalline hafnium
Journal of Applied Physics, 2009Co-Authors: U.m.r. Seelam, C. SuryanarayanaAbstract:A face-centered-cubic (Fcc) Phase was obtained in high-purity hafnium (Hf) metal powders subjected to mechanical milling in a high-energy SPEX shaker mill. X-ray diffraction and electron microscopy techniques were employed to evaluate the structural changes in the milled powder as a function of milling time. The effects of mechanical milling included a reduction in grain size, an increase in lattice strain, and formation of an Fcc Phase instead of an equilibrium hexagonal-close-packed (hcp) Phase. During milling, the grain size of Hf decreased to below about 7 nm. Additionally, there was approximately 6% increase in atomic volume during the formation of the Fcc Phase. Chemical analysis of the milled powder indicated the presence of significant amounts of interstitial impurities. Even though any or all of the above factors could contribute to the formation of the Fcc Phase in the milled powder, it appears that the high level of interstitial impurities is at least partially responsible for the formation of ...
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Control of bcc and Fcc Phase formation during mechanical alloying of Ti-Al-Nb
1995Co-Authors: F.s. Biancaniello, C. Suryanarayana, F.w. Gayle, Francis H. FroesAbstract:A Ti-Al-Nb alloy was processed by ball milling or mechanical alloying in a high energy shaker mill in an attempt to produce a fine grained BCC alloy. Previous studies of this alloy resulted in the formation of an amorphous Phase followed by a 100% Fcc alloy (probably a nitride Phase). In the present study, ball milling was conducted in two different laboratories with nitride- and oxide-free starting powders in each location. Two types of starting powders were used: pre-alloyed powders and mixed elemental powders of the same composition. The production of a 90% BCC/10% Fcc alloy was accomplished indicating that the production of 100% BCC alloy may be possible. The methods used to prevent the formation of nitrides and oxides of these very reactive constituents during mechanical alloying are discussed and x-ray diffraction results of the mechanically alloyed powders milled by various techniques are presented. The most important factor leading to amorphization and Fcc Phase formation appears to be contamination associated with periodic sampling of the alloy during ball milling even when dry, inert gas gloveboxes are used for powder transfer.
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Does a disordered γ-TiAl Phase exist in mechanically alloyed TiAl powders?
Intermetallics, 1995Co-Authors: C. SuryanarayanaAbstract:Abstract An Fcc Phase has been reported to form in mechanically alloyed titanium-aluminum alloys. This Fcc Phase forms after an amorphous Phase during milling and has been found to be stable up to very high temperatures. Different investigators have interpreted the formation of this Fcc Phase as (i) a product of crystallization of the amorphous Phase, (ii) a supersaturated solid solution of titanium in aluminum, (iii) the disordered form of the γ-TiAl Phase, or (iv) a contaminant Phase. The present paper analyzes the available results and concludes that this is a contaminant Phase, most probably TiN.
J. Henry - One of the best experts on this subject based on the ideXlab platform.
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radiation induced bcc Fcc Phase transformation in a fe3 ni alloy
Acta Materialia, 2018Co-Authors: L.t. Belkacemi, E. Meslin, B. Décamps, Bertrand Radiguet, J. HenryAbstract:Abstract The issue of neutron irradiation embrittlement of Reactor Pressure Vessel steels must be considered for Nuclear Power Plant life extension. This phenomenon partly arises from the existing interactions between dislocations and nanometric clusters composed of Cu, P, Si, Mn and Ni. The latter alloying element, playing a key role in the evolution of solute enriched clusters under irradiation, is the focus of this publication. To assess the effect of Ni on microstructure evolution under irradiation, particle accelerator based experiments were conducted. An under-saturated Fe3at.%Ni alloy was irradiated with self-ions, at 673 K, up to ∼1.2 dpa. Then, the microstructural damage was characterized, at the atomic scale, by conventional Transmission Electron Microscopy, Scanning Transmission Electron Microscopy coupled to Energy Dispersive X-ray Spectroscopy and Electron Energy Loss Spectroscopy, while chemical features were investigated by Atom Probe Tomography. Informations obtained by combining these coupled techniques provide evidence for the formation of a Fcc Phase, containing 25 at.%Ni, which can be either the disordered γ Phase or the ordered L12 type Fe3Ni Phase. The metastable or stable state of this Fcc Phase is discussed in the light of what is known from the literature. It is the first time that this BCC-Fcc Phase transformation is observed in an under-saturated α-FeNi alloy and this likely occurred via a Radiation Induced Precipitation (RIP) mechanism. Ni atom segregation is observed on cavities, dislocation lines and dislocation loops. The latter constitute nuclei for precipitates, leading to the formation of an additional segregation site for Ni: the precipitate Fcc - matrix BCC nearly coherent interface. Similar mechanisms are argued to be operating also in high Ni RPV steels under neutron irradiation.
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Radiation-induced bcc-Fcc Phase transformation in a Fe3%Ni alloy
Acta Materialia, 2018Co-Authors: L.t. Belkacemi, E. Meslin, B. Décamps, Bertrand Radiguet, J. HenryAbstract:Abstract The issue of neutron irradiation embrittlement of Reactor Pressure Vessel steels must be considered for Nuclear Power Plant life extension. This phenomenon partly arises from the existing interactions between dislocations and nanometric clusters composed of Cu, P, Si, Mn and Ni. The latter alloying element, playing a key role in the evolution of solute enriched clusters under irradiation, is the focus of this publication. To assess the effect of Ni on microstructure evolution under irradiation, particle accelerator based experiments were conducted. An under-saturated Fe3at.%Ni alloy was irradiated with self-ions, at 673 K, up to ∼1.2 dpa. Then, the microstructural damage was characterized, at the atomic scale, by conventional Transmission Electron Microscopy, Scanning Transmission Electron Microscopy coupled to Energy Dispersive X-ray Spectroscopy and Electron Energy Loss Spectroscopy, while chemical features were investigated by Atom Probe Tomography. Informations obtained by combining these coupled techniques provide evidence for the formation of a Fcc Phase, containing 25 at.%Ni, which can be either the disordered γ Phase or the ordered L12 type Fe3Ni Phase. The metastable or stable state of this Fcc Phase is discussed in the light of what is known from the literature. It is the first time that this BCC-Fcc Phase transformation is observed in an under-saturated α-FeNi alloy and this likely occurred via a Radiation Induced Precipitation (RIP) mechanism. Ni atom segregation is observed on cavities, dislocation lines and dislocation loops. The latter constitute nuclei for precipitates, leading to the formation of an additional segregation site for Ni: the precipitate Fcc - matrix BCC nearly coherent interface. Similar mechanisms are argued to be operating also in high Ni RPV steels under neutron irradiation.
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Radiation-induced bcc-Fcc Phase transformation in a Fe-3percentNi alloy
Acta Materialia, 2018Co-Authors: L.t. Belkacemi, E. Meslin, B. Décamps, Bertrand Radiguet, J. HenryAbstract:The issue of neutron irradiation embrittlement of Reactor Pressure Vessel steels must be considered for Nuclear Power Plant life extension. This phenomenon partly arises from the existing interactions between dislocations and nanometric clusters composed of Cu, P, Si, Mn and Ni. The latter alloying element, playing a key role in the evolution of solute enriched clusters under irradiation, is the focus of this publication. To assess the effect of Ni on microstructure evolution under irradiation, particle accelerator based experiments were conducted. An under-saturated Fe3at.percentNi alloy was irradiated with self-ions, at 673 K, up to 1.2 dpa. Then, the microstructural damage was characterized, at the atomic scale, by conventional Transmission Electron Microscopy, Scanning Transmission Electron Microscopy coupled to Energy Dispersive X-ray Spectroscopy and Electron Energy Loss Spectroscopy, while chemical features were investigated by Atom Probe Tomography. Informations obtained by combining these coupled techniques provide evidence for the formation of a Fcc Phase, containing 25at.percentNi, which can be either the disordered et947; Phase or the ordered L12 type Fe3Ni Phase. The metastable or stable state of this Fcc Phase is discussed in the light of what is known from the literature. It is the first time that this BCC-Fcc Phase transformation is observed in an under-saturated et945;-FeNi alloy and this likely occurred via a Radiation Induced Precipitation (RIP) mechanism. Ni atom segregation is observed on cavities, dislocation lines and dislocation loops. The latter constitute nuclei for precipitates, leading to the formation of an additional segregation site for Ni the precipitate Fcc - matrix BCC nearly coherent interface. Similar mechanisms are argued to be operating also in high Ni RPV steels under neutron irradiation.
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Radiation-induced bcc-Fcc Phase transformation in a Fe-3%Ni alloy
Acta Mater., 2018Co-Authors: L.t. Belkacemi, E. Meslin, B. Décamps, Bertrand Radiguet, J. HenryAbstract:The issue of neutron irradiation embrittlement of Reactor Pressure Vessel steels must be considered for Nuclear Power Plant life extension. This phenomenon partly arises from the existing interactions between dislocations and nanometric clusters composed of Cu, P, Si, Mn and Ni. The latter alloying element, playing a key role in the evolution of solute enriched clusters under irradiation, is the focus of this publication. To assess the effect of Ni on microstructure evolution under irradiation, particle accelerator based experiments were conducted. An under-saturated Fe3at.%Ni alloy was irradiated with self-ions, at 673 K, up to ∼1.2 dpa. Then, the microstructural damage was characterized, at the atomic scale, by conventional Transmission Electron Microscopy, Scanning Transmission Electron Microscopy coupled to Energy Dispersive X-ray Spectroscopy and Electron Energy Loss Spectroscopy, while chemical features were investigated by Atom Probe Tomography. Informations obtained by combining these coupled techniques provide evidence for the formation of a Fcc Phase, containing 25 at.%Ni, which can be either the disordered γ Phase or the ordered L12 type Fe3Ni Phase. The metastable or stable state of this Fcc Phase is discussed in the light of what is known from the literature. It is the first time that this BCC-Fcc Phase transformation is observed in an under-saturated α-FeNi alloy and this likely occurred via a Radiation Induced Precipitation (RIP) mechanism. Ni atom segregation is observed on cavities, dislocation lines and dislocation loops. The latter constitute nuclei for precipitates, leading to the formation of an additional segregation site for Ni: the precipitate Fcc - matrix BCC nearly coherent interface. Similar mechanisms are argued to be operating also in high Ni RPV steels under neutron irradiation.
Qingqiang Ren - One of the best experts on this subject based on the ideXlab platform.
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Proposed mechanism of HCP → Fcc Phase transition in titianium through first principles calculation and experiments.
Scientific reports, 2018Co-Authors: Jia Xi Yang, H.r. Gong, Min Song, Heng Lv Zhao, Qingqiang RenAbstract:By means of first principles calculation and experiments, a detailed mechanism is proposed to include the stages of slip, adjustment, and expansion for the HCP → Fcc Phase transformation with the prismatic relation of $${{\{}{10}\bar{{1}}{0}{\}}}_{{hcp}}{\parallel }{\{}{1}\bar{{1}}{0}{{\}}}_{{Fcc}}$$ and $${{[}{0001}{]}}_{{hcp}}{\parallel }{[}{001}{{]}}_{{Fcc}}$$ in titanium. It is revealed that the formation of four Fcc layers is preferable after the slip of Shockley partial dislocations of 1/6 $$\langle {1}\bar{{2}}{10}\rangle $$ on $${\{}{10}\bar{{1}}{0}{\}}$$ planes, and that the adjustment of interplanar spacing and the volume expansion are energetically favorable and could happen spontaneously without any energy barrier. It is also found that the transformed Fcc lattice first follows the c/a ratio (1.583) of HCP and then becomes an ideal Fcc structure (c/a = √2). The proposed mechanism could not only provide a deep understanding to the process of HCP → Fcc prismatic transformation in titanium, but also clarify the controversy regarding volume expansion of HCP-Fcc Phase transition of titanium in the literature.
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proposed mechanism of hcp Fcc Phase transition in titianium through first principles calculation and experiments
Scientific Reports, 2018Co-Authors: Jia Xi Yang, H.r. Gong, Min Song, Heng Lv Zhao, Qingqiang RenAbstract:By means of first principles calculation and experiments, a detailed mechanism is proposed to include the stages of slip, adjustment, and expansion for the HCP → Fcc Phase transformation with the prismatic relation of $${{\{}{10}\bar{{1}}{0}{\}}}_{{hcp}}{\parallel }{\{}{1}\bar{{1}}{0}{{\}}}_{{Fcc}}$$ and $${{[}{0001}{]}}_{{hcp}}{\parallel }{[}{001}{{]}}_{{Fcc}}$$ in titanium. It is revealed that the formation of four Fcc layers is preferable after the slip of Shockley partial dislocations of 1/6 $$\langle {1}\bar{{2}}{10}\rangle $$ on $${\{}{10}\bar{{1}}{0}{\}}$$ planes, and that the adjustment of interplanar spacing and the volume expansion are energetically favorable and could happen spontaneously without any energy barrier. It is also found that the transformed Fcc lattice first follows the c/a ratio (1.583) of HCP and then becomes an ideal Fcc structure (c/a = √2). The proposed mechanism could not only provide a deep understanding to the process of HCP → Fcc prismatic transformation in titanium, but also clarify the controversy regarding volume expansion of HCP-Fcc Phase transition of titanium in the literature.
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Proposed mechanism of HCP → Fcc Phase transition in titianium through first principles calculation and experiments
Nature Publishing Group, 2018Co-Authors: Jia Xi Yang, Min Song, Heng Lv Zhao, Hao Ran Gong, Qingqiang RenAbstract:Abstract By means of first principles calculation and experiments, a detailed mechanism is proposed to include the stages of slip, adjustment, and expansion for the HCP → Fcc Phase transformation with the prismatic relation of $${{\{}{10}\bar{{1}}{0}{\}}}_{{hcp}}{\parallel }{\{}{1}\bar{{1}}{0}{{\}}}_{{Fcc}}$$ { 10 1 ¯ 0 } hcp ∥ { 1 1 ¯ 0 } Fcc and $${{[}{0001}{]}}_{{hcp}}{\parallel }{[}{001}{{]}}_{{Fcc}}$$ [ 0001 ] hcp ∥ [ 001 ] Fcc in titanium. It is revealed that the formation of four Fcc layers is preferable after the slip of Shockley partial dislocations of 1/6 $$\langle {1}\bar{{2}}{10}\rangle $$ 〈 1 2 ¯ 10 〉 on $${\{}{10}\bar{{1}}{0}{\}}$$ { 10 1 ¯ 0 } planes, and that the adjustment of interplanar spacing and the volume expansion are energetically favorable and could happen spontaneously without any energy barrier. It is also found that the transformed Fcc lattice first follows the c/a ratio (1.583) of HCP and then becomes an ideal Fcc structure (c/a = √2). The proposed mechanism could not only provide a deep understanding to the process of HCP → Fcc prismatic transformation in titanium, but also clarify the controversy regarding volume expansion of HCP-Fcc Phase transition of titanium in the literature
Ramesh Chandra - One of the best experts on this subject based on the ideXlab platform.
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Study of thermal stability and mechanical properties of Fcc Phase Zr22W19N58 thin films deposited by reactive magnetron sputtering
Surface and Coatings Technology, 2014Co-Authors: P. Dubey, V. Arya, Saurabh Kumar Srivastava, Devendra Singh, Ramesh ChandraAbstract:Abstract Thermal stability and mechanical properties of zirconium tungsten nitride (Zr–W–N) thin films have been studied. Nano-structured Zr–W–N thin films have been deposited on Si (100) substrates by reactive magnetron sputtering at varying substrate temperatures T s (100°–600 °C). For 100 °C ≤ T s ≤ 600 °C, X-ray diffraction patterns of the films show a crystalline Fcc Phase with (111) and (200) preferred crystallographic orientations of grains. Maximum wear resistance (H/E r ~ 0.22) and maximum resistance to fatigue fracture (H 3 /E r 2 ~ 1.0 GPa) have been obtained for the film deposited at T s = 400 °C. Post annealing of the films deposited at 400 °C has been carried out in air from 100°–600 °C. Oxygen starts to be incorporated at 300 °C and films begin to peel off above 400 °C due to increase in oxygen incorporation. Hardness and elastic modulus of annealed films increase with increasing strain.
