Papers by Keyword: Supercooled Liquid Region

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Authors: Zhi Hui Ma, Hong Juan Su, Xiang Huai Dong
Abstract: Linear and nonlinear viscoelastic behaviors of a Zr55Al10Ni5Cu30 bulk metallic glass are investigated through experiments and described by the fictive stress model. Systematic deviations between the predicted stress-strain curves by fictive stress model and by the experimental results were found. In order to describe the flow stress curves of the Zr55Al10Ni5Cu30 BMG at different temperatures and strain rates in the supercooled liquid region more precisely, the fictive stress model was modified. The parameters of the model were optimized by the genetic algorithm, and a time relaxation factor Z' was introduced. The comparisons of the predicted compressive stress-strain curves and extrusion load-punch stroke curve by the modified fictive stress model with the experimental data show good agreements.
449
Authors: Kai Chen Kuo, Pee Yew Lee, Jai Yush Yen
Abstract: In the current study, the amorphization behavior of mechanically alloyed Ni57Zr20Ti22Ge1 powder was examined in details. The conventional X-ray diffraction results confirm that the fully amorphous powders formed after 5 hours of milling. The thermal stability of the Ni57Zr20Ti22Ge1 amorphous powders was investigated by differential scanning calorimeter (DSC). As the results demonstrated, the glass transition temperature (Tg) and the crystallization temperature (Tx) are 761 K and 839 K, respectively. The supercooled liquid region ΔT is 78 K. The appearance of wide supercooled liquid region may be mainly due to the Ge additions which cause the increasing differences in atomic size of mechanically alloyed Ni57Zr20Ti22Ge1 powders.
48
Authors: M. Stoica, Jürgen Eckert, Stefan Roth, Ludwig Schultz, Alain Reza Yavari, Å. Kvick
77
Authors: Chung Kwei Lin, Pee Yew Lee
Abstract: In the present study, Cu60Zr30Ti10 metallic glass powders were prepared by mechanical alloying of pure Cu, Zr, and Ti powder mixtures. Cu60Zr30Ti10 metallic glass composite powders were obtained after 5 h of milling as confirmed by X-ray diffraction and transmission electron microscopy. The metallic glass powders were found to exhibit a supercooled liquid region before crystallization. Cu60Zr30Ti10 bulk metallic glass were synthesized by vacuum hot pressing the as-milled Cu60Zr30Ti10 metallic glass powders at 723 K in the pressure range of 0.72 ~ 1.20 GPa. Cu60Zr30Ti10 BMG with nanocrystalline precipitates homogeneously embedded in a highly dense glassy matrix was successfully prepared under applied pressures. It was found that the pressure could enhance the thermal stability and prolong the existence of amorphous phase inside Cu60Zr30Ti10 powders.
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Authors: W.B. Kim, B.J. Ye, S. Yi
Abstract: The effects of partial replacements of Zr by Y in the alloy Ni60Zr25-xAl8Yx(x=0 and 7 at %) on the crystallization behaviors of amorphous alloys were studied using isothermally heattreated ribbons. With the partial replacement, the supercooled liquid region upon continuous heating was significantly extended indicating that crystallization can be effectively suppressed by the optimum amount of Zr replacement by Y. The first phase appeared during crystallization was identified as the ternary compound AlNi2Zr while the single exothermic event could be observed upon heating the amorphous ribbons. The AlNi2Zr phase was decomposed into binary compounds upon further heating. Therefore, the extended supercooled liquid region of the alloy Ni60Zr25Al8Y7 was attributed to the suppression of AlNi2Zr phase formation by the partial replacement of Zr by Y. The effects of Y on the crystallization behaviors were discussed on the basis of atomic configuration of the supercooled liquid.
941
Authors: K.B. Kim, Paul J. Warren, Brian Cantor, Jürgen Eckert
657
Authors: C.C. Wang, Chung Kwei Lin, Y.L. Lin, J.S. Chen, R.R. Jen, Pee Yew Lee
Abstract: In the present study, WC/Cu60Zr30Ti10 metallic glass composite powders were prepared by mechanical alloying of pure Cu, Zr, Ti, and WC powder mixtures. Cu60Zr30Ti10 metallic glass composite powders were obtained after 5 h of milling as confirmed by X-ray diffraction and differential scanning calorimetry. The metallic glass composites powders were found to exhibit a supercooled liquid region before crystallization. Bulk metallic glass (BMG) composites were synthesized by vacuum hot pressing the as-milled Cu60Zr30Ti10 metallic glass composite powders at 723 K in the pressure range of 0.72-1.20 GPa. BMG composite with submicron WC particles homogeneously embedded in a highly dense anocrystalline/amorphous matrix was successfully prepared under applied pressure of 1.20 GPa. It was found that the pressure could enhance the thermal stability and promotes nocrystallization of WC/Cu60Zr30Ti10 BMG composites.
3443
Authors: Hyung Seop Shin, Y.-J. Jung, Ki Hyun Kim, Jung Ho Ahn, Hidemi Kato, Akihisa Inoue
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