利用Gleeble 3500热模拟试验机研究了块体非晶合金Zr₆₁Cu₂₅Al₁₂Ti₂ (ZT1)和Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ (Vit105)过冷液相区的压缩变形性能及其流变行为。结果表明,温度和应变速率影响其在过冷液相区的变形模式,主要包括3种典型方式：低温或高应变速率时局部剪切导致的脆性断裂,较高温度或者低应变速率时的Newtonian流变,中温区间或者较高应变速率时的非Newtonian流变。给出了2种合金Newtonian流变向非Newtonian流变转变的边界条件及过冷液相区的变形图。当压缩应变速率小于1 × 10^-3 s^-1时,ZT1和Vit105分别在678~703 K和703~738 K温度区间表现出Newtonian流变行为,适合进行热塑性加工。利用自由体积模型分析发现,与ZT1相比,Vit105合金的流变激活体积(V_a = 0.123~0.234 nm³)明显小于ZT1 (V_a = 0.137~0.590 nm³)。综合合金玻璃转变温度和脆度系数,指出在过冷液相区Vit105比ZT1具有更高的稳定性和更好的可加工性。

The plastic deformation of amorphous alloys at room temperature is limited to small shear band zones and minimal strain. However, amorphous alloys in the supercooled liquid region exhibit superplasticity and have high forming ability. Zr₆₁Cu₂₅Al₁₂Ti₂ (ZT1) and Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ (Vit105) amorphous alloys have excellent forming ability and similar mechanical properties at room temperature or low temperature. They have broad application prospects as flexible components, but little work has been conducted on the superplasticity of ZT1. This work examined the rheological behavior of the supercooled liquid of two amorphous alloys to provide a theoretical basis for microplastic deformation. ZT1 and Vit105 amorphous alloys were prepared by copper mold suction casting. The high-temperature rheological behaviors of the two amorphous alloys were investigated using Gleeble3500. Variations in temperature and strain rate influence the steady-state stress obviously in the supercooled liquid region. Theological transformation behaviors of the different Zr-based amorphous alloys were analyzed based on the viscous flow model. The plastic deformation in the supercooled liquid region included brittle fracture caused by local shear in low-temperature range or at a high strain rate, non-Newtonian rheology at high strain rates in the middle-temperature range, and Newtonian rheology at low strain rates in the high-temperature range. In the plastic deformation process at a low strain rate, nanocrystals are formed inside the amorphous alloy due to the combined actions of thermal and stress driving forces. With a compressive rate less than 1 × 10^-3 s^-1, ZT1 and Vit105 exhibited Newtonian flow over the temperature ranges of 678-703 K and 703-738 K, respectively. According to the free volume model, the calculated activation volumes for ZT1 and Vit105 were 0.137-0.590 nm³ and 0.123-0.234 nm³, respectively. The much smaller activation volume in Newtonian flow was associated with the higher diffusibility and atomistic mobility of the free volume in the material. The Vit105 amorphous alloy showed higher stability and glass formability, which is more convenient for thermoplastic processing, due to the combination of a high glass transition temperature and fragility parameter.