Zr61Ti2Cu25Al12非晶合金过冷液体的动力学行为：采用快速扫描量热法

Kinetic Behavior of Supercooled Liquid of Zr61Ti2Cu25Al12 Amorphous Alloy: by Flash Differential Scanning Calorimetry

摘要:

根据经典形核理论，构建了Zr₆₁Ti₂Cu₂₅Al₁₂合金的时间-温度-转变（TTT）曲线，由此估算并修正得出其临界冷却速率 R_c≈63 K/s，应用玻璃形成能力准则对其可靠性进行评估，阐述了形核率I和生长速率U在不同过冷液相区内对晶化机制的控制。采用快速扫描量热与常规热分析相结合对Zr₆₁Ti₂Cu₂₅Al₁₂非晶合金实现6个数量级（10^-2~10⁴ K/s）升温速率变化，从而展现出在超宽范围内过冷液体依赖于升温速率的动力学行为：首先，升温速率与特征温度之间的依赖关系符合Vogel-Fulcher-Tammann方程；其次，脆性系数（m=30~41）的小幅变化意味着其过冷液体结构随温度变化比较平缓，从而展现出具有一定的“强”液体行为，使得该合金具有一定的玻璃形成能力。本研究为Zr₆₁Ti₂Cu₂₅Al₁₂非晶合金的制备，尤其是过冷液相区内的塑性成形以及热处理工艺制定提供了技术指导和理论依据。

Abstract:

Based on the classical nucleation theory, a time-temperature-transformation (TTT) curve of Zr₆₁Ti₂Cu₂₅Al₁₂ alloy was constructed, and its critical cooling rate R_c was estimated and modified as about 63 K/s. The reliability of this estimation was evaluated using the glass-forming ability criteria, and the dominant roles of nucleation rate I and growth rate U on the crystallization mechanism in different supercooled liquid regions were explained. Combining flash differential scanning calorimetry with conventional thermal analysis, a heating rate range spanning six orders of magnitude (10^-2–10⁴ K/s) was achieved for the Zr₆₁Ti₂Cu₂₅Al₁₂ amorphous alloy, demonstrating the heating-rate dependence of kinetic behavior of supercooled liquid over an ultra-wide range. Results show that firstly, the dependence of heating rate on characteristic temperatures follows the Vogel-Fulcher-Tammann equation. Secondly, the small change in fragility coefficient (m=30–41) means that its supercooled liquid structure changes relatively smoothly with temperature, exhibiting “strong” liquid behavior to a certain extent, making the alloy have a certain glass-forming ability. This study provides technical guidance and theoretical basis for the preparation of Zr₆₁Ti₂Cu₂₅Al₁₂ amorphous alloy, especially for the plastic forming in the supercooled liquid region and the formulation of heat treatment process.