Phase selection rule of high-entropy metallic glasses with different short-to-medium-range orders

When an equiatomic multi-component alloy is quenched from its molten state down to room temperature,either a solid solution crystalline alloy or a metallic glass is formed.The former is called a high-entropy alloy,whereas the latter is referred as a high-entropy metallic glass(HE-MG).In such multicomponent alloys,thermodynamic parame-ters,e.g.,the mixing entropy,the mixing enthalpy and other parameters such as atomic size mismatch,determine the resulting phases.

Effects of casting current on structure and properties of a nanostructured Zr-Cu-Fe-Al bulk metallic glass

The effects of casting currents on the thermophysical behaviors, atomic and nanoscale structure, and mechanical properties of two Zr-based-bulk metallic glasses, i.e., Zr59Cu33A18 and Zr59（Cuo.55Feo.45）33A18, were studied by using differential scanning calorimetry, wide-angle X-ray diffraction, and small-angle X-ray scattering, as well as compression tests. The casting currents can be tuned to change the casting initiative temperature. Results revealed that there is no anomalous structural change for the Zr59Cu33A18 molten liquid before crystallization during cooling with different casting currents. In contrast, liquid-state phase separation was suggested to occur in the Zr59（Cuo.55Feo.45）33A18 molten liquid prepared using lower casting current before crystallization during cooling. The position shift of the first sharp diffraction peak for the diffraction pattern of Zr59（Cuo.55Feo.45）33A18 shows that the density of the molten liquid may decrease upon cooling at different casting currents. The small-angle X-ray scattering results indicate that the heterogeneity of the Zr59（Cuo.55- Feo.gs）33A18 metallic glasses increases with decreasing the casting temperature. As a result, the metallic glasses with a liquid-state phase separation possess better mechanical properties, including higher-yielding stress and more significant compressive ductility. The increase in degree of heterogeneity formed by nanoscale liquid-state phase separation and their interactions with the shear bands for the Zr-Cu-Fe-Al bulk metallic glasses were suggested to be responsible for the enhanced mechanical properties.

Photocatalytic properties of CaTi_(2)O_(5)via a facile additive-free aqueous strategy with different pH values

CaTi_(2)O_(5)was selectively prepared by a solvothermal process without template and surfactant.The phase of the as-prepared samples was determined by X-ray diffraction(XRD).The microstructure was characterized by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Results found that pH values had a crucial effect on the crystal phase and shape evolution of the samples.CaTi_(2)O_(5)sample prepared at pH of 5.2 shows high efficient light harvesting,large surface area and crystallinity.Moreover,CaTi_(2)O_(5)shuttle-like sample shows good photocatalytic activity against methyl orange due to its longer and thinner shuttle-like morphology and high crystallinity,enhanced light harvesting and large surface area.The photocatalytic rate of CaTi_(2)O_(5)shuttle-like structure reaches 0.1988 min-1 for 25-min methyl orange degradation under the ultraviolet light irradiation and displays an excellent photostability with a degradation efficiency of 0.1952 min^(-1)after four cycles.