Search

Those peritectic alloys with large positive mixing enthalpy usually display metastable liquid phase separation. Here, the solidification kinetics for a model Fe 50 Cu 50 alloy in broad cooling rate R c range was predicted by phase-field simulations and confirmed by drop tube experiments. Near-equilibrium peritectic solidification occurs in small R c regime below 5.62×10 2 K s −1 . As R c rises beyond 7.76×10 2 K s −1 , metastable phase separation takes place and results in the formation of a dispersed structure. Afterwards, multilayer core-shell structures appear, and the layer-number varies from two-layer to six-layer with further increasing R c . Once R c exceeds 3.64×10 5 K s −1 , a dispersed structure once again forms because the core-shell dynamic condition is not satisfied. Non-equilibrium peritectic solidification is induced if R c is greater than 5.85×10 5 K s −1 . [ABSTRACT FROM AUTHOR]

Abstract: In this paper, YVO4:Yb3+,Er3+ microspheres have been successfully prepared through a facile hydrothermal method assisted with disodium ethylenediaminetetraacetic acid and citric acid. X-ray diffraction, field emission scanning electron microscopy, energy disperse X-ray spectroscopy, high resolution transmission electron microscopy, and photoluminescence spectra were used to characterize the samples. The results reveal that the as-prepared YVO4:Yb3+,Er3+ samples are well-crystallized and spherical in shape. Moreover, the microspheres with diameters of 6–8μm are assembled by numerous submicron cuboids. Under the excitation of a 980nm laser diode, the samples show the characteristic emissions of Er3+ and the green emissions at 525nm of 2H11/2→4I15/2 are dominantly strong. [Copyright &y& Elsevier]

• A novel nanostructured Fe 39 Cr 39 Ni 14 C 8 eutectic high entropy alloy was developed. • The rapid solidification alloy exhibits a typical fully lamellar FCC1/FCC2 eutectic structure. • FCC1 phase has a unique cube-cube coherent relationship with FCC2 phase. • Its high hardness and high yield strength originate mainly from the phase interface strengthening. A novel nanostructured Fe 39 Cr 39 Ni 14 C 8 eutectic high entropy alloy (EHEA) was developed by rapid solidification. Detailed characterization reveals that the rapidly solidified Fe 39 Cr 39 Ni 14 C 8 EHEA shows a nano-lamellar structure consisting of alternative FCC1 (∼120 nm in width) and FCC2 (∼80 nm) phases with a coherent relationship and possesses a high hardness of 463HV (∼4.5 GPa) and a high yield strength of 1.45GPa. They are mainly attributed to the unique ultrafine eutectic structure. This finding would shed new light on the development of FCC1/FCC2-nanostructured EHEAs with excellent mechanical properties. [ABSTRACT FROM AUTHOR]