A5019536088- Quasicrystal Structures and Properties
- Theoretical and Computational Physics
- High Entropy Alloys Studies
- Intermetallics and Advanced Alloy Properties
- X-ray Diffraction in Crystallography
- High-Temperature Coating Behaviors
- Metallic Glasses and Amorphous Alloys
- Boron and Carbon Nanomaterials Research
- Rare-earth and actinide compounds
- Material Dynamics and Properties
- Characterization and Applications of Magnetic Nanoparticles
- Surface and Thin Film Phenomena
- Graphene research and applications
- Metallurgical and Alloy Processes
- Mineralogy and Gemology Studies
- nanoparticles nucleation surface interactions
- Advanced Materials Characterization Techniques
- Thermodynamic and Structural Properties of Metals and Alloys
- Physics of Superconductivity and Magnetism
- Advanced Chemical Physics Studies
- Iron-based superconductors research
- Microstructure and mechanical properties
- Machine Learning in Materials Science
- Aluminum Alloy Microstructure Properties
- Nanocluster Synthesis and Applications
Carnegie Mellon University
2015-2024
University of Science and Technology of China
2016-2024
Suzhou University of Science and Technology
2024
California Miramar University
2017
Kent State University
2014
University of Virginia
2008
University of Pittsburgh
2005-2007
Délégation Paris 7
2000
Université Paris Cité
2000
Yale University
1998
Abstract Developing affordable and light high-temperature materials alternative to Ni-base superalloys has significantly increased the efforts in designing advanced ferritic superalloys. However, currently developed still exhibit low strengths, which limits their usage. Here we use a CALPHAD-based high-throughput computational method design light, strong, low-cost high-entropy alloys for elevated-temperature applications. Through screening, precipitation-strengthened lightweight are...
Abstract Refractory high‐entropy alloys (RHEAs) show promising applications at high temperatures. However, achieving strengths elevated temperatures above 1173K is still challenging due to heat softening. Using intrinsic material characteristics as the alloy‐design principles, a single‐phase body‐centered‐cubic (BCC) CrMoNbV RHEA with high‐temperature (beyond 1000 MPa 1273 K) designed, superior other reported RHEAs well conventional superalloys. The origin of strength revealed by in situ...
Abstract Energy efficiency is motivating the search for new high-temperature (high-T) metals. Some body-centered-cubic (BCC) random multicomponent “high-entropy alloys (HEAs)” based on refractory elements (Cr-Mo-Nb-Ta-V-W-Hf-Ti-Zr) possess exceptional strengths at high temperatures but physical origins of this outstanding behavior are not known. Here we show, using integrated in-situ neutron-diffraction (ND), high-resolution transmission electron microscopy (HRTEM), and recent theory, that...
We obtain quasicrystalline structures in Monte Carlo simulations of a simple two-component Lennard-Jones system two dimensions. The quasicrystal, which shows tenfold symmetry, appears to be an equilibrium state the system. Although structure corresponds tiling plane with rhombuses, it is not Penrose pattern.
We investigate the possibility of tailoring electronic properties isoreticular metal-organic materials by replacing metal atom in cluster and doping. The structure M-IRMOF1, where IRMOF1 stands for framework 1 M = Be, Mg, Ca, Zn, Cd, was examined using density-functional theory. results show that these have similar band gaps (ca. 3.5 eV) a conduction is split into two bands, lower which has width varies with substitution. This variation prompted us to whether doping Al or Li could be used...
The properties of materials change, sometimes catastrophically, as alloying elements and impurities accumulate preferentially at grain boundaries. Studies bicrystals show that regular atomic patterns often arise a result this solute segregation high-symmetry boundaries, but it is not known whether superstructures exist general boundaries in polycrystals. In bismuth-doped polycrystalline nickel, we found ordered, segregation-induced boundary occur randomly selected these reconstructions are...
Abstract High entropy alloys (HEAs) are multicomponent compounds whose high configurational allows them to solidify into a single phase, with simple crystal lattice structure. Some HEAs exhibit desirable properties, such as specific strength, ductility, and corrosion resistance, while challenging the scientist make confident predictions in face of multiple competing phases. We demonstrate phase stability alloy system Cr–Mo–Nb–V, for which some its binary subsystems subject separation complex...
The unusual behavior observed in the coefficient of thermal expansion and specific heat capacity CrFeNi, CoCrNi, CoCrFeNi medium/high-entropy alloys is commonly referred to as K-state effect. It shown be independent Curie temperature, demonstrated by temperature-dependent magnetic moment measurements. alloy chosen for detailed characterization; potential reasons effect such texture, recrystallization, second-phase precipitation are ruled out. An examination electronic structure indicates...
We investigate short range order in liquid and supercooled Fe Fe-based metallic glass using ab initio simulation methods. analyze the data to quantify degree of local icosahedral polytetrahedral understand role alloying controlling geometric frustration. Comparing elemental Cu [P. Ganesh M. Widom, Phys. Rev. B 74, 134205 (2006)] we find that is greater than Cu, possibly because disclination line defects are more easily incorporated into bcc environments fcc. In glass-forming alloys...
A growing body of experiments display indirect evidence icosahedral structures in supercooled liquid metals. Computer simulations provide more direct but generally rely on approximate interatomic potentials unproven accuracy. We use first-principles molecular dynamics to generate realistic atomic configurations, providing structural detail not directly available from experiment, based forces that are reliable than conventional simulations. analyze copper, for which recent experimental...
We investigate the quasicrystalline state of a two-dimensional binary alloy in discrete tiling approximation. Through transfer-matrix calculations we determine configurational entropy over range concentrations. find that density is maximized by with tenfold symmetry at quasicrystal concentration. Derivatives its maximum yield values for phason elastic constants. Our results confirm existence quasi-long-range translational order equilibrium alloys and lend support to random-tiling model quasicrystals.
First-principles molecular dynamics simulations reveal a liquid-liquid phase transition in supercooled elemental silicon. Two phases coexist below Tc approximately 1232 K and above pc -12 kB. The low-density is nearly tetracoordinated, with pseudogap at the Fermi surface, while high-density more highly coordinated metallic nature. observed through formation of van der Waals loops pressure-volume isotherms Tc.
The crystal structure of boron is unique among chemical elements, highly complex, and imperfectly known. Experimentalists report that the $\ensuremath{\beta}$-rhombohedral (black) form stable over all temperatures from absolute zero to melting. However, early calculations found its energy be greater than $\ensuremath{\alpha}$-rhombohedral (red) form, implying $\ensuremath{\beta}$ phase cannot at low temperatures. Furthermore, exhibits partially occupied sites, seemingly in conflict with...
Low-energy reflectivity of electrons from single- and multilayer graphene is examined both theoretically experimentally. A series minima in the over energy range 0--8 eV are found, with number depending on layers. Using first-principles computations, it demonstrated that a freestanding $n$-layer slab produces $n\ensuremath{-}1$ minima. This same result also found experimentally for supported SiO${}_{2}$. For bonded onto other substrates argued similar expected, although certain cases an...