Search

The Ca-Fe-O system is essential for understanding the chemical equilibria involved in copper production using calcium ferrite slags. It forms a core component of a complex 20-component Cu-Pb-Zn-Fe-Ca-Si-O-S-Al-Mg-Cr-Na-As-Sn-Sb-Bi-Ag-Au-Ni-Co system developed for diverse applications in ferrous and non-ferrous metallurgy. This study re-evaluates the Ca-Fe-O system using recent experimental phase equilibrium data acquired by the authors (Cheng et al., 2024) [1] through advanced equilibration, quenching, and Electron Probe X-ray Microanalysis (EPMA) techniques. Thermodynamic properties of solid phases have been revised in accordance with the recommendations for the third generation of Calphad databases. Liquid endmember heat capacities have been refined to describe glass transition behaviour in supercooled liquids. The updated properties of liquid endmembers significantly extend the applicability of the database, enabling lower-temperature applications related to toxic element leaching from amorphous and partially crystallized slags. The revised, higher melting temperature of CaO enhances predictive accuracy in multicomponent systems. Liquid slag phase has been modelled within the Modified Quasichemical Formalism to account for short-range ordering phenomena. Recent advances in modelling and optimization technique made it possible to assess experimental data within the Ca-Fe-O system as an integral part of a large multicomponent dataset, applicable for industrial conditions. [ABSTRACT FROM AUTHOR]

Equiatomic metallic glasses are expected to show different properties compared to one principal element-based metallic glasses due to different configurational entropy and atomic-level order. Here, we compare the rheological and transport properties of the supercooled liquid states of compositionally related equiatomic Pd 20 Pt 20 Cu 20 Ni 20 P 20 and Pt-rich Pt 57.3 Cu 14.6 Ni 5.3 P 22.8 metallic glasses. The temperature dependent viscosity values were calculated from thermoplastic molding experiments. The kinetic fragility and isothermal crystallization times were compared to evaluate the correlation between the viscous flow and the diffusivity. The equiatomic metallic glass exhibits stronger liquid behavior, but faster crystallization kinetics than Pt-based metallic glass. The thermoplastic formability of two metallic glasses at different length scales was evaluated using molding and drawing experiments. • Viscosity and crystallization kinetics of equiatomic and one principal element based metallic glasses are studied. • The equiatomic metallic glass shows weak temperature dependence of viscosity. • The equiatomic metallic glass shows fast crystallization kinetics despite higher viscosity. • The results indicate that equiatomic compositions are not necessarily high-entropy in their glassy state. [ABSTRACT FROM AUTHOR]

We explore the concept of correlative activation free energy (CAFE) for the analysis and interpretation of viscosity data of a collection of 847 inorganic oxide glass formers that exhibit various degrees of non-Arrhenius behavior. The CAFE model formalism is strictly based on transition state theory and accounts for the variation in the activation barrier height for the viscous dissipation due to the structural evolution the system undergoes upon traversing the glass transition regime. Thus, fitting parameters are meaningful in a statistical thermodynamic context. Compared to the VFT and MYEGA equations, fits using the CAFE model are more robust when extrapolating to infinite temperature because the latter encodes non-enthalpic contributions to the rate coefficient more realistically. The CAFE model-based analysis reveals a strong connection between melt fragility and the degree of change in the potential energy landscape with temperature. Accordingly, while the average ground-state potential energy of the glass forming liquid gradually increases with temperature, the energy of the activated state remains relatively invariant. Our analysis also allows one to estimate the number of atoms involved in the viscous relaxation process, which ranges from approximately 10 to 50 atoms for the oxide glass formers studied. We observe that thermally activated dynamic phenomena exhibited by glassy networks, such as the mixed alkali effect, persist into the supercooled liquid state. Graphical abstract for "Correlative activation free energy (CAFE) model: Application to Viscous Processes in Inorganic Oxide Glass-Formers," by C. Beg, J. Byeong, N. Berman, and J. Kieffer. This graphic depicts how the temperature dependence of viscosity coefficients, measured by means of a steady-state shear deformation at a macroscopic scale, is interpreted using the proposed correlative activation free energy (CAFE) model to yield information about a glass forming system's energy landscape and the viscous dissipation mechanism. Typical glass forming liquids exhibit viscoelastic responses that ubiquitously deviate from Arrhenius behavior, which gave rise to the strong-fragile classification. The CAFE model quantifies such behavior in terms of a free energy landscape that changes with temperature, i.e., both the ground state potential energy and configurational entropy. Accordingly, the more fragile the glass former, the more substantial the change in the activation free energy as a function of temperature. Based on the CAFE analysis, the number of atoms that partake in the dissipation event is estimated to be larger for strong and smaller for fragile liquids. [Display omitted] [ABSTRACT FROM AUTHOR]

Bulk metallic glasses (BMGs) possess higher strength than crystalline alloys because crack propagation is halted through an amorphous structure without grain boundaries or crystal defects. Nanoinclusions can further enhance mechanical properties. Here we investigate how the formation of nanocrystals into a Ti 41.2 Zr 10.6 Cu 39.1 Pd 9.1 BMG matrix via controlled annealing that leads to devitrification of the bulk microstructure, as well as chemical changes to the surface oxide layer, affects mechanical and biological performance. The BMG nanocrystalline composite (BMGC, 12.8 % crystallinity produced via annealing at 415 °C for 5 min, based on crystallisation kinetics studies) was compared to the fully amorphous BMG and the fully crystalline counterpart (annealed at 415 °C and 60 min). BMGC fracture strength (1374.6 MPa) was higher than that of the amorphous BMG (1303.1 MPa) and the fully crystalline specimen (644.4 MPa). Young's moduli correlated negatively with the degree of crystallisation (78.3–66.2 GPa). The results from in vitro tests on MC3T3-E1 illustrate that the surface chemistry plays a crucial role enhancing osteoblastogenesis: the presence of Zr oxides, wettable surfaces and large values of polar component of Surface Free Energy due to the nanocrystals, and a thinner oxide layer with low concentrations of Cu x O, positioned BMGC as the preferred substrate. Tailoring amorphicity-to-crystallinity ratio in a Ti-Zr-Cu-Pd BMG is a route to create multifunctional substrates. [Display omitted] • Tailoring the amorphicity-to-crystallinity ratio in a Ti-Zr-Cu-Pd BMG via annealing. • Inclusion of nanocrystals within the BMG matrix to increase alloy strength. • Concurrent validation including thermo-, mechanical, chemical and biological tests. • BMG-Composite outperforms pure amorphous and crystalline counterparts. • Enhanced biological performance of BMGC due to surface chemistry and Free Energy. [ABSTRACT FROM AUTHOR]

An icosahedral quasicrystalline (IQ) phase forms in the as-spun ribbons as well as as-cast bulk rods with a diameter of 2 mm for the Ti 39 Zr 39 Ni 20 Ag 2 and Ti 39 Zr 39 Ni 20 Cu 2 alloys. The Ti 39 Zr 39 Ni 20 Ag 2 alloy ribbon consists of a mostly amorphous phase containing a small amount of IQ phases and exhibits good bending plasticity. The decomposition of their metastable phases occurs accompanying exothermic peaks at 694 K and 890 K, followed by an endothermic peak at 991 K. The former two peaks are due to the transitions from amorphous to IQ + cF96-(Ti, Zr) 2 Ni phases, and to C14-TiZrNi Laves phase, respectively. The latter endothermic peak originates from the change of IQ to C14-TiZrNi Laves and β -(Ti, Zr) phases. Compared with the complex phase decomposition behavior of the quaternary alloys, the decomposition of the metastable phase of the Ti 40 Zr 40 Ni 20 alloy ribbon occurs accompanying only an endothermic peak at a peak temperature of 952 K, followed by a melting peak. For the quaternary alloys, the as-cast rods consist of an IQ single phase, in contrast to three phases of IQ, C14-TiZrNi Laves and β -(Ti, Zr) phases for the Ti 40 Zr 40 Ni 20 rod. The ternary alloy rod fractures in the quasi-cleavage fracture mode, while the fracture mode of the quaternary alloy rod is cleavage fracture. In the Ti 39 Zr 39 Ni 20 Ag 2 rod, IQ phase displays a spherical morphology with an average diameter of approximately 0.27 μm. The formation of the bulk IQ rod as well as the enhancement of amorphous phase formability for the Ag/Cu-containing IQ alloys are presumably due to the stabilization of supercooled liquid caused by the development of more dense-packed atomic configurations resulting from the sequent atomic size change of Zr > Ti > Ag/Cu > Ni as well as by the necessity of the separation to Ti-Zr-Ni and Ti-Zr-Ag/Cu atomic pairs resulting from the positive heats of mixing for Ni-Ag and Ni-Cu pairs. [Display omitted] • Single IQ phase formed in the Ti 39 Zr 39 Ni 20 Ag 2 and Ti 39 Zr 39 Ni 20 Cu 2 alloy rods. • The phase decompositions of IQ alloy ribbons were investigated in depth. • Ti 39 Zr 39 Ni 20 Ag 2 alloy ribbon containing the IQ phase exhibits good bending plasticity. • Morphology of free-growing spherical quasicrystals was observed in TiZrNiAg alloy rod. [ABSTRACT FROM AUTHOR]

This study investigated the impact of Ta on the structure and properties of Zr 46 Cu 46 Al 4 Ti 4) 100-x Ta x (x = 0, 1, 1.5, 2 at%) bulk metallic glass composites (BMGCs). The addition of Ta led to a gradual increase in the glass transition temperature, while the crystallization onset temperature remained nearly constant. This resulted in a decrease in the supercooled liquid phase region and a reduction in the glass-forming ability (GFA). The room temperature uniaxial compression tests revealed that the addition of Ta initially increased the plasticity of the alloys, followed by a subsequent decrease. The alloy with 1.5 at% Ta exhibited superior properties, including the highest fracture strength (2033 MPa) and plasticity (8.1 %). The Vickers hardness tests revealed that the addition of Ta led to an increase of the hardness in the glass matrix region of alloys from 512.8 HV to 550.9 HV. In conclusion, a moderate amount of Ta element can enhance both the fracture strength and plasticity of Zr-based BMGCs, as well as improve the hardness of the alloy glass matrix. • A reasonable amount of Ta addition can significantly improve the mechanical properties of Zr-based BMGCs. • The maximum plasticity at room temperature of 8.1 % when Ta is added at 1.5 at%. • The addition of Ta densifies the localized stacking of atoms and increases the hardness of the amorphous regions of alloys. [ABSTRACT FROM AUTHOR]

This study explores the intricate heat transfer dynamics and thermographic patterns during the phase change from supercooled liquid water to ice. Using high-resolution, high-speed infrared thermography, real-time temperature data were captured during the freezing process. The resulting temperature profiles reveal critical insights into the freezing dynamics, particularly highlighting the rapid phenomena of recalescence in supercooled conditions. Notably, this study represents the first time recalescence, a rapid and previously elusive phenomenon, captured and documented in the scientific literature. Additionally, a mathematical model is developed to describe the recalescence phase on macro scale. These findings have practical relevance for various industries, aiding in the design of more efficient anti−/de-icing technologies, refrigeration systems, weather prediction models, and cryopreservation techniques. The study also opens new avenues for further exploration in understanding phase transitions in supercooled water. • First-ever high-speed infrared thermography captures rapid recalescence during freezing of supercooled water droplets. • Infrared data reveals heat transfer mechanisms, focusing on latent heat release and temperature profiles • A sigmoid-based model explains temperature evolution in recalescence, offering a macro-scale view of the process. • Findings impact anti-/de-icing, refrigeration, weather prediction, and cryopreservation, benefiting multiple industries. [ABSTRACT FROM AUTHOR]

Mutual acquisition of phase-stability and controllable phase-transition becomes a predominant criterion of phase-change materials for the practical long-term energy storage but seems contradictory always. Here a strategy combining coordination and hydrogen bonds hierarchically to create a supercooled liquid in a core-shell coordination structure is reported, addressing that demand successfully. This new material is composed of a Mn-methylurea complex (MM) core and the hierarchically bonded erythritols shell. MM glass core with a viscosity of 10 8 Pa·s determines its thermal phase-stability. As discovered, the ingenious ligand-exchange between erythritol and Cl - ion coordinated with MM core accounts for this effectively reversible phase-transition. This can be triggered by a small shear-stress of 10 Pa within tens of seconds, exhibiting good practicability. Thermodynamics and kinetics of phase-transition are explored., (© 2025 Wiley‐VCH GmbH.)