Increasing the kinetic stability of bulk metallic glasses
Increasing the kinetic stability of bulk metallic glasses
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DOI：
10.1016/j.actamat.2015.11.048
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发表时间：
2016-02
期刊：
影响因子：
9.4
通讯作者：
Jun-Qiang Wang;Y. Shen;J. Perepezko;M. Ediger
中科院分区：
文献类型：
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作者：
Jun-Qiang Wang;Y. Shen;J. Perepezko;M. Ediger
金属玻璃属于非平衡材料，加热后的玻璃化转变温度tg可以用来表征玻璃的动力学稳定性。众所周知，玻璃化转变以下的退火会诱发降低玻璃化焓的弛豫过程。我们证明了液冷金基金属玻璃可以通过最佳退火处理获得非常高的动力学稳定性，从而在28k时大幅增加inTg；这比通常报道的增幅大3-5倍。测得的热焓下降1100 J/mol，约为冷却玻璃与平衡晶态差的50%，达到过冷液体的外推热焓。在对弛豫过程进行综合考察的基础上，首次提出了焓-温度-时间（ETT）图来确定最优退火条件。在平衡状态下，动态稳定性的增加（用手的增加来测量）与焓的减少之间建立了直接关系。
Metallic glasses are non-equilibrium materials and the glass transition temperature upon heatingTg,hcan be used to characterize the kinetic stability of the glass. Annealing below the glass transition is well-known to induce relaxation processes that reduce the glass enthalpy. We demonstrate that a liquid-cooled Au-based metallic glass can achieve very high kinetic stability by an optimal annealing treatment to yield a large increase inTg,hof 28 K; this is 3–5 times larger than the increase usually reported. The measured enthalpy decrease of 1100 J/mol is about 50% of the difference between the as-cooled glass and the equilibrium crystalline state and reaches the extrapolated enthalpy of the supercooled liquid. The optimal annealing conditions can be determined by an enthalpy-temperature-time (ETT) diagram which is proposed for the first time based on the comprehensive examination of relaxation processes. At equilibrium, a direct relation is established between the increase in kinetic stability as measured by the increase inTghand the enthalpy decrease.