The first order L-G phase transition in liquid Ag and Ag-Cu alloys is driven by deviatoric strain
The first order L-G phase transition in liquid Ag and Ag-Cu alloys is driven by deviatoric strain
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DOI：
10.1016/j.scriptamat.2020.113695
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发表时间：
2021-03
影响因子：
6
通讯作者：
Q. An;W. Johnson;K. Samwer;Sydney L. Corona;W. Goddard
中科院分区：
文献类型：
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作者：
Q. An;W. Johnson;K. Samwer;Sydney L. Corona;W. Goddard
过冷液相（L-相）可以经历一级构型相变，转变为晶相（X-相）或亚稳的、构型不均匀的刚性玻璃相（G-相）。为了研究L-G相变的机制，我们采用分子动力学模拟研究了二元Cu-Ag体系中G相的形成。我们发现，G相的形成是由局部畸变能量的减少所产生的偏应变在液相中，并展示其局部分布。畸变能的减少贡献了L-G转变潜热的80%以上，这表明液体中空间变化的随机弹性场的凝聚是一阶L-G转变的主要原因。通过将这种分析应用于元素Ag的结晶和G相的形成，我们表明，在纯金属的情况下，偏应变能是L-G和L-X转变的主导驱动力。
An undercooled liquid-phase (L-phase) can undergo a first order configurational phase transition to either a crystal phase (X-phase) or a metastable, configurationally heterogeneous, rigid glassy phase (G-phase). To investigate the underlying mechanism of the L-G transition, we employ molecular dynamics simulations to study G-phase formation in a binary Cu-Ag system. We find that G-phase formation is driven by the reduction of local distortion energy arising from deviatoric strains in the liquid phase and demonstrate its local distribution. Reduction of distortion energy contributes over 80% of the latent heat of the L-G transition, suggesting that condensation of spatially varying random elastic fields in the liquid is primarily responsible for the first order L-G transition. By applying this analysis to crystallization and G-phase formation in elementary Ag, we show that deviatoric strain energy is the dominant driving force for the L-G and L-X transition also in the case of the pure metal.