Thermodynamic anomaly of the sub-Tg relaxation in hyperquenched metallic glasses
Thermodynamic anomaly of the sub-Tg relaxation in hyperquenched metallic glasses
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DOI：
10.1063/1.4803136
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发表时间：
2013-05-07
影响因子：
4.4
通讯作者：
Yue, Yuanzheng
中科院分区：
文献类型：
--
作者：
Hu, Lina;Zhou, Chao;Yue, Yuanzheng
最近，我们观察到一种不寻常的非单调玻璃弛豫现象，即，超淬CuZrAl玻璃带的三步亚T-g弛豫[L. N. Hu和Y. Z. Yue，Appl. Phys. Lett. 98，081904（2011）]。在本工作中，我们揭示了这种异常行为的起源，通过研究冷却速率依赖的亚Tg焓弛豫在两种金属玻璃。对于Cu 46 Zr 46 Al 8玻璃带，只有在低于临界冷却速率时，亚T-g焓弛豫模式才随退火温度呈现三步趋势。对于La 55 Al 25 Ni 20玻璃带，亚T-g焓弛豫开始的活化能也随着制造的冷却速率而非单调地变化。这些反常的弛豫现象可以用低温团簇和高温团簇之间的竞争来解释。通过比较Cu_（46）Zr_（46）Al_（8）和La_（55）Al_（25）Ni_（20）的化学不均匀性，我们预测这种反常弛豫行为可能是HQ金属玻璃的普遍特征。(C)2013 AIP Publishing LLC.
Recently, we observed an unusual non-monotonic glass relaxation phenomenon, i.e., the three-step sub-T-g relaxation in hyperquenched CuZrAl glass ribbons [L. N. Hu and Y. Z. Yue, Appl. Phys. Lett. 98, 081904 (2011)]. In the present work, we reveal the origin of this abnormal behavior by studying the cooling rate dependence of the sub-T-g enthalpy relaxation in two metallic glasses. For the Cu46Zr46Al8 glass ribbons the sub-T-g enthalpy relaxation pattern exhibits a three-step trend with the annealing temperature only when the ribbons are fabricated below a critical cooling rate. For the La55Al25Ni20 glass ribbons the activation energy for the onset of the sub-T-g enthalpy relaxation also varies non-monotonically with the cooling rate of fabrication. These abnormal relaxation phenomena are explained in terms of the competition between the low and the high temperature clusters during the fragile-to-strong transition. By comparisons of chemical heterogeneity between Cu46Zr46Al8 and La55Al25Ni20, we predict that the abnormal relaxation behavior could be a general feature for the HQ metallic glasses. (C) 2013 AIP Publishing LLC.