Abstract The viscosity of metallic glasses is considered to remain constant during thermoplastic forming operations. Here, we quantify the time dependent change in isothermal viscosity of Pt57.5Cu14.7Ni5.3P22.5 and Zr35Ti30Cu8.25Be26.75 glass formers in the supercooled liquid state. The samples were isothermally held prior to thermoplastic molding to probe the viscosity at different times. The viscosity values were extracted from the filling length of mold cavities. The viscosity increased with annealing time and the rate of increase was found to be largely independent of temperature and type of glass former. However, the viscosity increase was higher in the outer parts of samples which experienced higher shear rate during molding. Crystal nucleation and growth contributions are considered to explain the observed changes in effective viscosity of remaining amorphous phase. Our results suggest that thermoplastic forming is an effective tool in analyzing subtle changes in structure and viscosity of metallic glass supercooled liquids.

中文翻译：

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时间对金属玻璃过冷液体等温粘度的影响

摘要 金属玻璃的粘度被认为在热塑性成型操作过程中保持不变。在这里，我们量化了过冷液态下 Pt57.5Cu14.7Ni5.3P22.5 和 Zr35Ti30Cu8.25Be26.75 玻璃形成剂的等温粘度随时间的变化。在热塑性塑料成型之前将样品保持等温以探测不同时间的粘度。粘度值是从模腔的填充长度中提取的。粘度随退火时间增加，并且发现增加的速率很大程度上与温度和玻璃形成剂的类型无关。然而，在模塑过程中经历更高剪切速率的样品的外部中粘度增加更高。晶体成核和生长贡献被认为可以解释观察到的剩余非晶相有效粘度的变化。我们的结果表明，热塑性成型是分析金属玻璃过冷液体结构和粘度细微变化的有效工具。