( 1. 中国科学院 金属研究所， 沈阳 110016;
2. Ris国家实验室， Roskilde DK-4000， 丹麦)
摘 要: 研究了Mg60Cu30Y10大块非晶合金在过冷液相区的流变行为。 结果表明： 随着温度升高和应变速率增加， 平衡态的牛顿流转变为非平衡态的非牛顿流； 其流变行为对于温度和应变速率非常敏感。 由粘度与应变速率的关系， 根据Arrhenius型VFT方程， 确定了流动应力、 应变速率和温度的关系。 Mg60Cu30Y10大块非晶合金在过冷液相区的流变性能依赖于温度与变形速率， 其微观机制可由自由体积模型解释， 为大块非晶合金流变成形工艺的实现提供理论依据： 温度高于玻璃转变温度以后， 自由体积的增加使非晶合金变形过程中能够移动的原子数目随之增加， 自由体积周围的原子沿外力的作用方向移动， 即宏观上的塑性流变行为。 应变速率增加， 由热激活引起的自由体积增加不能满足更多原子流变所需的空间体积， 导致牛顿流向非牛顿流转变。
关键字: 镁基大块非晶； 过冷液相区； 流变行为； 本构关系
（ 1. Institute of Metal Research, Chinese Academy of Sciences,
Shenyang 110016, China;
2. Risφ National Laboratory, Roskilde DK-4000, Denmark）
Abstract: Viscous flow behavior of Mg60Cu30Y10 bulk metallic glass in supercooled liquid region was investigated. The supercooled liquids exhibit that Newtonian viscosity in equilibrium state transforms to a non-Newtonian viscosity in non-equilibrium state with temperature and strain rate increasing. According to VFT (Vogel-Fulcher-Tammann) equation with the Arrhenius function, the relation between flow stress and viscosity and temperature was established. Viscous flow of Mg60Cu30Y10 bulk metallic glass depends on temperature and strain rate. It can be described with the free-volume model and used to interpret the implement of Mg-based bulk metallic glass viscous forming process. When the temperature is higher than glass transition temperature, the number of atoms which can jump during deformation of bulk metallic glass increases. Atomic jumps are biased in the direction of the external force. This forms the plastic flow showed in macroscopic. With strain rate increasing, free volume obtained from thermal fluctuations can't meet the need of more and more atomic jumps. It results in steady state Newtonian viscosity transfer to non-Newtonian viscosity.
Key words: Mg-based bulk metallic glass; supercooled liquid region; viscous flow behavior; constitutive equation
