Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extreme conditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50 is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physical properties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change are successfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relatively insensitive to the strain rate γ̇ when γ̇ ranges from 7.5 × 108 to 2 × 109/s, which are values reachable in QIC experiments, with a magnitude of the order of 10−2kB/atom per GPa. However, when γ̇ is extremely high (>2×109/s), a notable increase in entropy production rate with γ̇ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated that entropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase in configurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamental relation between microstructure evolution and plastic dissipation.

中文翻译：

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金属玻璃准等熵压缩塑性热力学研究

准等熵压缩（QIC）中的熵产生对于理解极端条件下材料的性能至关重要。然而，在这种情况下，熵的起源和准确量化仍然是长期存在的挑战。在这项工作中，建立了一个框架来量化熵产生和分配，以及它们与 QIC 微观结构变化的关系。以Cu50Zr50为模型材料，通过分子动力学模拟其压缩过程。基于原子模拟的物理性质和自由能，恢复了热力学路径，并且通过所提出的框架成功地量化了熵产生及其与微观结构变化的关系。与直觉相反，当 γ̇ 范围为 7.5 × 108 至 2 × 109/s（这是 QIC 实验中可达到的值）时，金属玻璃 QIC 过程中的熵产生对应变率 γ̇ 相对不敏感，其量级为 10−每 GPa 2kB/原子。然而，当γ̇极高(＞2×109/s)时，观察到随着γ̇熵产率显着增加。发现泰勒-昆尼因子随应变变化，但在模拟状态下不随应变率变化。结果表明，与振动部分相比，熵的产生主要由构型部分主导。在速率不敏感的情况下，构型熵的增加与微观结构变化的香农熵量化呈线性关系，与泰勒-奎尼因子呈拉伸指数关系。熵的量化有望为微观结构演化与塑性耗散之间的基本关系提供热力学见解。