The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
R E Ryltsev - One of the best experts on this subject based on the ideXlab platform.
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a single phase sctizrhf high entropy alloy with thermally stable hexagonal close Packed Structure
Intermetallics, 2020Co-Authors: S A Uporov, Kh S Estemirova, V A Bykov, D A Zamyatin, R E RyltsevAbstract:Abstract High-entropy alloys forming non-cubic crystal Structures are intriguing systems for both scientific and functional viewpoints. Hexagonal-Structured HEAs are among them. In this work, we have fabricated a single-phase hexagonal close-Packed phase in ScTiZrHf system. To verify its structural stability, we anneal the alloy samples at 973 K for a long time from 15 up to 140 h. Structural analysis reveals that the HEA retains its single-phase Structure after the thermal treatment. To characterize the material, we examine its electron-transport and magnetic properties over a wide temperature range. The alloy electrical resistivity has purely metallic temperature dependence, while its absolute values are rather high. The thermal conductivity in this material is very low. The analysis of the transport properties reveals a noticeable lattice contribution ( ≈ 50% ) in total thermal conductivity probably caused by a strongly defected crystal Structure. The alloy magnetization demonstrates complicated temperature dependence, which is well described by a superposition of Curie–Weiss and valence-electron contributions. Based on this suggestion, we fit experimental magnetization data and extract the electron density of states (DOS) at the Fermi level as ≈ 1 e V − 1 . To address the properties of interatomic interaction in the system, we perform ab-initio molecular dynamics simulations of the liquid phase. The data obtained indicate unambiguously the absence of strong chemical interaction between alloy components as well as the nearly additive character of the liquid mixture that supports the results obtained experimentally.
Min Song - One of the best experts on this subject based on the ideXlab platform.
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three dimensional crystallographic orientation relationships for hexagonal close Packed Structure to face centered cubic Structure transformation in pure titanium
Scripta Materialia, 2019Co-Authors: Bingqiang Wei, Yong Liu, Min SongAbstract:Abstract In this work, two types of stress induced hexagonal close Packed Structure to face centered cubic Structure transformation were observed in cold-rolled pure titanium. The corresponding transformation mechanisms were revealed by high resolution transmission electron microscopy. By using stereographic projections and selected area electron diffraction simulations, the three dimensional orientation relationships for the two types of phase transformation were deduced for the first time. The deduced orientation relationships were also verified by high resolution transmission electron microscopy observations, and the dark side of the basal-type face centered cubic phase was revealed at the atomic scale.
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proposed mechanism of twin formation during hexagonal close Packed Structure to face centered cubic phase transition
Solid State Communications, 2018Co-Authors: Jianshi Yang, L C Liu, H R Gong, Min SongAbstract:Abstract Detailed process, critical energy, and critical shear stress of twin formation during hexagonal-close-Packed (HCP) to face-centered-cubic (FCC) transition are proposed through first principles calculation. It reveals that a lower critical energy is needed for HCP→FCC basal transition with twin formation than that without twin. The relative magnitude of critical shear stresses is strongly correlated with c/a ratio of HCP metals, and fundamentally determines the appearance of HCP→FCC basal transition and phase-transition twin. The predicted results bring about reasonable explanations to two puzzling points regarding Mg and twin formation in the literature.
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mechanisms for deformation induced hexagonal close Packed Structure to face centered cubic Structure transformation in zirconium
Scripta Materialia, 2017Co-Authors: Henglv Zhao, Min SongAbstract:Abstract Two distinctive orientation relations between hexagonal close-Packed (HCP) phase and face-centered cubic (FCC) phase were observed simultaneously in cold-rolled pure Zr, which were denoted as B-type and P-type orientation relations according to whether the phase interface is parallel to the basal plane or prism plane of the HCP matrix. The mechanisms for the phase transformation generating the two different HCP-FCC orientation relations were thoroughly analyzed. B-type orientation relation was achieved when HCP to FCC phase transformation occurred via collective gliding of Shockley partial dislocations on basal planes, while P-type orientation relation was attained through pure-shuffle and shear-shuffle mechanisms.
S A Uporov - One of the best experts on this subject based on the ideXlab platform.
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a single phase sctizrhf high entropy alloy with thermally stable hexagonal close Packed Structure
Intermetallics, 2020Co-Authors: S A Uporov, Kh S Estemirova, V A Bykov, D A Zamyatin, R E RyltsevAbstract:Abstract High-entropy alloys forming non-cubic crystal Structures are intriguing systems for both scientific and functional viewpoints. Hexagonal-Structured HEAs are among them. In this work, we have fabricated a single-phase hexagonal close-Packed phase in ScTiZrHf system. To verify its structural stability, we anneal the alloy samples at 973 K for a long time from 15 up to 140 h. Structural analysis reveals that the HEA retains its single-phase Structure after the thermal treatment. To characterize the material, we examine its electron-transport and magnetic properties over a wide temperature range. The alloy electrical resistivity has purely metallic temperature dependence, while its absolute values are rather high. The thermal conductivity in this material is very low. The analysis of the transport properties reveals a noticeable lattice contribution ( ≈ 50% ) in total thermal conductivity probably caused by a strongly defected crystal Structure. The alloy magnetization demonstrates complicated temperature dependence, which is well described by a superposition of Curie–Weiss and valence-electron contributions. Based on this suggestion, we fit experimental magnetization data and extract the electron density of states (DOS) at the Fermi level as ≈ 1 e V − 1 . To address the properties of interatomic interaction in the system, we perform ab-initio molecular dynamics simulations of the liquid phase. The data obtained indicate unambiguously the absence of strong chemical interaction between alloy components as well as the nearly additive character of the liquid mixture that supports the results obtained experimentally.
Takayoshi Nakano - One of the best experts on this subject based on the ideXlab platform.
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development of ti zr hf y la high entropy alloys with dual hexagonal close Packed Structure
Scripta Materialia, 2020Co-Authors: Takeshi Nagase, Mitsuharu Todai, Takayoshi NakanoAbstract:Abstract TiZrHfYLa0.2 high-entropy alloys (HEAs) with dual hexagonal-closed-Packed (HCP) Structures were designed based on the concept of liquid phase separation (LPS) and segregation for enhancing the immiscibility of the constituent elements. The LPS leads to a particular solidification microStructure on the free surface side and Cu-hearth contacted area in the ingots. The dual HCP Structures with equi-axis Ti–Zr–Hf dendrite and Y-La-rich interdendrite were observed at most regions of the arc-melted ingots. The mixing enthalpy among the constituent elements and predicted phase diagrams constructed by the Materials Project were effective for the alloy design of the HEAs with dual HCP Structures.
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Plastic deformation mechanisms of biomedical Co–Cr–Mo alloy single crystals with hexagonal close-Packed Structure
Scripta Materialia, 2018Co-Authors: Wataru Kaita, Koji Hagihara, Luís Augusto Rocha, Takayoshi NakanoAbstract:Abstract This is the first report of the successful fabrication of Co–Cr–Mo biomedical alloy single crystals with a hexagonal close-Packed (hcp) Structure and the resultant clarification of its deformation behavior. The (0001)〈11 2 ¯ 0〉 basal and {1 1 ¯ 00}〈11 2 ¯ 0〉 prismatic slip systems were found to be predominately operative. The critical resolved shear stresses for the basal and prismatic slip systems at ambient temperature are ~ 204 and ~ 272 MPa, respectively, which are much higher than ~ 54 MPa for {111}〈11 2 ¯ 〉 slip in the face-centered cubic (fcc) Co–Cr–Mo phase, quantitatively demonstrating that the hcp phase acts as an effective strengthening phase.
Gaowu Qin - One of the best experts on this subject based on the ideXlab platform.
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magnesium alloys strengthened by nanosaucer precipitates with confined new topologically close Packed Structure
Crystal Growth & Design, 2018Co-Authors: Hongbo Xie, Hucheng Pan, Yuping Ren, Shineng Sun, Liqing Wang, Hong Zhao, Boshu Liu, Gaowu QinAbstract:The γ″ nanosaucer precipitates in many Mg-RE-Zn(Ag) alloys, also named the G. P. zones in some cases such as in the Mg–Ca–Al(Zn) alloys, play the critical role in strengthening the α-Mg matrix and enhancing their creep resistance. However, the previous reports on the crystal Structure of γ″ phase are still controversial at present, and thus it is hard to correlate the γ″ phase with the mechanical properties of Mg alloys. In this study, we confirmed a new topological close-Packed (TCP) Structure for the γ″ precipitate in a typical peak-aged Mg–Gd–Zn alloy using Cs-corrected high-angle annular dark-field-scanning transmission electron microscopy (HAADF-STEM) and computational simulation. The new Structure is totally different from the commonly accepted Structure for the γ″ phase that consisted of three atomic layers. In contrast, this TCP nanosaucer precipitate is composed of the monolayer atomic icosahedral clusters with five (0001)γ″ atomic layers (hexagon Structure, space group: P6/mmm, a = 5.56 A, c = 5...
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magnetically induced phase separation and magnetic properties of co mo hexagonal close Packed Structure thin films
Applied Physics Letters, 2003Co-Authors: K Oikawa, Gaowu Qin, M Sato, O Kitakami, Y Shimada, J Sato, K Fukamichi, K IshidaAbstract:Magnetically induced phase separation along the Curie temperature in the hexagonal-close-Packed phase of a Co–Mo binary system has been predicted by thermodynamic calculations. Furthermore, the phase separation and magnetic properties of Co–Mo sputtered thin films have been investigated. Nanoscale compositional fluctuation caused by the magnetically induced phase separation has been confirmed in the films deposited on a heated substrate in the same manner as Co–Cr-based alloys. The magnetic anisotropy constant of the Co–Mo films is larger than that of Co–Cr films. From these results, it is concluded that the Co–Mo system is promising for use as a base alloy system for high density recording media.
