大块金属玻璃Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5)的流变行为研究

The rheological behavior of bulk metallic glass Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5)

采用静态拉伸方法在连续升温条件下动态地测量了大块金属玻璃Zr4 1 Ti1 4Cu1 2 5Ni1 0 Be2 2 5(Vit1 )的黏度随温度的变化关系 .在应变速率与温度的关系曲线中 ,观测到了与玻璃转变和晶化过程相联系的多个应变速率峰 .在玻璃转变温度Tg 以上 ,大块金属玻璃Zr4 1 Ti1 4Cu1 2 5Ni1 0 Be2 2 5的过冷液体呈现Newton流体特征 ,其黏度与温度的关系符合Vogel Fulcher Tammann (VFT)关系式 ,拟合得到脆度D =36 ,VFT温度T0 =31 9K ,脆度参数m =30 ,这说明Zr4 1 Ti1 4Cu1 2 5Ni1 0 Be2 2 5的过冷液体是一种类似于硅酸盐类的“强”液体 .在玻璃转变温度Tg 以下 ,粘度与温度的关系偏离VFT关系 ,从结构弛豫的观点出发 。

The temperature dependence of viscosity of the bulk metallic glass Zr 41 Ti 14 Cu 12 5 Ni 10 Be 22 5 (Vit1) under constant heating condition was obtained by application of static extension measurement. A few strain rate peaks, which are associated with the glass transition and multistep crystallization, were observed in the temperature strain rate curve. Above the glass transition temperature, the supercooled liquid of the bulk metallic glass showed the Newtonian rheological characteristic, and its temperature dependences of viscosity in supercooled liquid region can be fitted well with the Vogel Fulcher Tammann(VFT) equation. The sample exhibited the fragility parameter D * value of 36, the VFT temperature T 0 of 319K and the fragility m value of 30 It was shown that the Vit1 alloy is a strong liquid, similar to sodium silicate liquids. However, the relation between temperature and viscosity deviated from VFT equation below the glass transition temperature.The phenomenon is tentatively interpreted in terms of free volume model and structure relaxation concept.