Molecular Theory Group, Colorado School of Mines, Golden, Colorado 80401, USA.
J Chem Phys. 2014 Feb 28;140(8):084501. doi: 10.1063/1.4865336.
Though discovered more than a half century ago metallic glasses remain a scientific enigma. Unlike crystalline metals, characterized by short, medium, and long-range order, in metallic glasses short and medium-range order persist, though long-range order is absent. This fact has prompted research to develop structural descriptions of metallic glasses. Among these are cluster-based models that attribute amorphous structure to the existence of clusters that are incommensurate with crystalline periodicity. Not addressed, however, are the chemical factors stabilizing these clusters and promoting their interconnections. We have found that glass formers are characterized by a rich cluster chemistry that above the glass transformation temperature promotes exchange as well as static and vibronic sharing of atoms between clusters. The vibronic mechanism induces correlated motions between neighboring clusters and we hypothesize that the distance over which these motions are correlated mediates metallic glass stability and influences critical cooling rates.
虽然金属玻璃在半个多世纪前就被发现了，但它仍然是一个科学谜团。与具有短程、中程和长程有序的晶态金属不同，金属玻璃中短程和中程有序仍然存在，而长程有序则不存在。这一事实促使人们研究开发金属玻璃的结构描述。其中包括基于团簇的模型，该模型将非晶态结构归因于与晶体周期性不相符的团簇的存在。然而，这些模型并没有解决稳定这些团簇并促进它们相互连接的化学因素。我们发现，玻璃形成体的特征是丰富的团簇化学，在玻璃转变温度以上，团簇之间通过交换以及原子的静态和振动态共享来促进连接。振动态机制诱导相邻团簇之间的相关运动，我们假设这些运动相关的距离调节了金属玻璃的稳定性，并影响了临界冷却速率。
