Effects of partitioned enthalpy of mixing on glass-forming ability
WX Song and SJ Zhao, JOURNAL OF CHEMICAL PHYSICS, 142, 144504 (2015).
We explore the inherent reason at atomic level for the glass-forming ability of alloys by molecular simulation, in which the effect of partitioned enthalpy of mixing is studied. Based on Morse potential, we divide the enthalpy of mixing into three parts: the chemical part (Delta(Enn)), strain part (Delta(Estrain)), and non-bond part (Delta(Ennn)). We find that a large negative Delta(Enn) value represents strong AB chemical bonding in AB alloy and is the driving force to form a local ordered structure, meanwhile the transformed local ordered structure needs to satisfy the condition (Delta(Enn)/2 + Delta(Estrain)) < 0 to be stabilized. Understanding the chemical and strain parts of enthalpy of mixing is helpful to design a new metallic glass with a good glass forming ability. Moreover, two types of metallic glasses (i.e., "strain dominant" and "chemical dominant") are classified according to the relative importance between chemical effect and strain effect, which enriches our knowledge of the forming mechanism of metallic glass. Finally, a soft sphere model is established, different from the common hard sphere model. (C) 2015 AIP Publishing LLC.
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