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The structural evolution in the undercooled liquid plays an essential role in comprehending the crystallization mechanism, which is of benefit to understand the glass-forming ability (GFA), the thermal stability, and the development of glassy alloy (GA) with excellent properties. In this work, Zr 61 Ti 2 Cu 25 Al 12 GAs with different undercooled states were obtained by means of electromagnetic levitation. The Zr 61 Ti 2 Cu 25 Al 12 GA can achieve an undercooling degree of 226 K, which is larger than previously reported GAs. Calorimetric analysis indicates a more relaxed state occurs in the GA cooled from the larger undercooling. Hardness tests show that deep undercooling can lead to a significant increase in hardness compared to a low undercooling level. It might be attributed to a liquid-liquid transition, bringing out an obvious change in the atomic volume of the glassy phase. In addition, a pronounced ordered structure apparently exists when the system reaches the larger undercooling degree. Our findings provide a new perspective for the study of the undercooled liquid, and the solidification kinetics of GAs. • Structure of Zr 61 Ti 2 Cu 25 Al 12 GA is modulated by vitrification at different undercoolings via electromagnetic levitation. • The Zr 61 Ti 2 Cu 25 Al 12 GA achieves a 226 K undercooling degree, which is larger than previously reported GAs. • Our work provides a new perspective for the study of undercooled liquid and the solidification kinetics of GAs. [ABSTRACT FROM AUTHOR]

Medium entropy alloys (MEAs) strengthened by L1 2 ordered intermetallics have attracted extensive attention because of their unique mechanical properties that critically depend on the constituent elements. In this work, we design a CoCrNiAl 3 Ti 3 Cu 6 Nb 0.8 MEA possessing bimodal L1 2 nano-precipitates to achieve improved synergy of strength and ductility. The as-prepared MEA exhibit a yield strength of 1.16 GPa, a tensile strength of 1.55 GPa, and a uniform elongation of 28%. The improved mechanical responses are attributed to the simultaneously operated strong- and weak-pair coupling effects and the hetero-deformation induced strengthening that derived from the bimodal distributed L1 2 nano-precipitates. The results presented herein demonstrate that bimodal distributed nano-precipitates might be a new strategy toward synergy of strength and ductility in MEAs. [Display omitted] • A new non-equiamotic CoCrNiAl 3 Ti 3 Cu 6 Nb 0.8 medium entropy alloy (MEA) was designed. • The MEA exhibit strength-ductility synergy exceeded those reported on CoCrNi and derivatives. • The improved synergy derived from bimodal size distributed nanoscale coherent γ'. • Two pair coupling and hetero-deformation induced strengthening play key roles. [ABSTRACT FROM AUTHOR]

Abstract: The crystal structure of the deuteride of Ti0.85Mo0.15 alloy Ti0.85Mo0.15D1.47 is determined by neutron powder diffraction to be a tetragonally distorted fluorite-type structure similar to that of ɛ-phase in Ti–H system. The D concentration and c/a axial ratio of this phase are significantly lower than that in the Ti–H system. The formation of ɛ-phase in the Ti–Mo–H system supports the hypothesis that the electron density change play a role in the δ–ɛ phase transition. Considerable broadening of the reflections is observed in the diffraction patterns, and attributed to the D concentration inhomogeneity and anisotropic microstrain in the lattice of the deuteride. [Copyright &y& Elsevier]

The hydrogenation and dehydrogenation behaviors of a zirconium alloy were in-situ studied by scanning electron microscopy and transmission electron microscopy. The zirconium alloy can absorb hydrogen to form Zr hydride which is enhanced by the relaxation of inner stress in the alloy. The hydrogen is generated from an ion/electron beam stimulated decomposition of an organometallic precursor, trimethyl (methylcyclopentadienyl) platinum (IV), in a scanning electron microscope and focused ion beam system. The formed δ -type zirconium hydride that has a face centered cubic structure was observed to grow as preferentially oriented platelets in the zirconium alloy matrix. The platelets have a common crystallographic relationship of [010] α //[1-10] δ , (001) α //(111) δ . The dehydrogenation of the zirconium hydride was in-situ investigated in a transmission electron microscope by heating the materials. It was found that the δ -ZrH 1.5–1.66 hydride transformed into ζ -ZrH 0.25 at 450 °C even at a longer heating time. The experiment demonstrates a new way for in-situ study of hydrogenation behaviors of other hydrogen storage alloys. [ABSTRACT FROM AUTHOR]

Abstract: The detailed structural information of the deuteride of a null matrix Ti–Mo alloy containing 33at.% of Mo is studied by complementation of the neutron and X-ray powder diffraction techniques. The deuteride containing ∼1.8 deuterium atoms per alloy atom forms a titanium δ-hydride type of structure with deuterium atoms in the tetrahedral interstitial sites. The line broadening analysis of the deuteride phase suggests that the deuterization of the alloy causes strong lattice deformation effects, and the micro-strain is likely to be dislocation induced. In comparison with the deformation of the host Ti–Mo alloy matrix lattice, a relaxation effect is observed for the deformation of the interstitial deuterium sublattice. [Copyright &y& Elsevier]