铝-铅异质固液界面预熔化的原子模拟研究

Premelting plays a central role in a number of technologically important phenomena, such as nucleation, sintering, liquid-metal embrittlement and hot tears during casting. Significant progress has been realized over the past three decades in the application of atomistic simulations to the studies of premelting. However, such progress is limited in the studies of the solid-vapor and solid-solid interfacial premelting. The current proposal is aimed at carrying out pioneering simulation and computational studies on the solid-liquid interfacial premelting. We propose to target the new developments of the methods for detecting premelting precursors, to be applicable in the investigations on the onset mechanism for chemically heterogeneous alloy solid-liquid interfacial premelting. The proposed work will also involve the quantitatively studies into the relationships between the premelting and temperature, interfacial orientation, interfacial atomistic structure, interfacial shape and interfacial alloy solute concentration, for an illustrative and representative chemically heterogeneous Al-Pb solid-liquid interfacial system. As well as the investigation into one significant impact of the premelting on the application of such alloy. The proposed research will provide essential data to facilitate the new advancements of the interfacial thermodynamics.

预熔化相变在一系列具有极高应用价值的重要物理现象中扮演着核心角色，如形核、烧结、液态金属致脆和铸件热裂等。应用原子模拟技术研究预熔化相变在过去三十年中取得了巨大进步。然而，这些进步局限于固汽界面和固固界面的预熔化相变研究。本项目旨在先驱性地开展固液界面体系预熔化相变的原子模拟与计算研究。我们拟针对铝铅固液界面这一具有代表性的异质固液界面体系，定量研究该界面预熔化的发生机理，探索随温度、界面方向、界面微观结构、界面形状及界面合金浓度的变化规律，以及研究预熔化对该合金材料应用的一项重要影响。本项目研究的开展将为界面相变理论新的发展提供重要数据。

预熔化相变在一系列具有极高应用价值的重要物理现象中扮演着核心角色，如形核、烧结 、液态金属致脆和铸件热裂等。应用原子模拟技术研究预熔化相变在过去三十年中取得了巨大进步。然而已有进步局限于固汽界面和固固界面的预熔化相变研究。本项目针对铝铅固液界面这一具有代表性的异质固液界面体系，开展固液界面体系预熔化相变的原子模拟与计算研究。提出了利用局域界面结构关键热力学和界面微观结构的精密表征技术、及预熔化铝-铅合金体系铅夹杂在铝单晶中的平衡态模拟技术。开发了应用于异质固液界面体系的预熔化体系分离势能的计算方法。基于不同温度下、不同界面方向、不同界面曲率下铝-铅固液和液液界面原子模拟结果和计算方法，多种热力学量延界面法向上分布函数的变化规律，讨论了操控预熔化厚度与液相夹杂 物输运性能的理论可能。此外，在本项目的资助下，发展了一套固液界面系统相变动力学和平衡态热力学的金兹堡-朗道凝固界面动力学理论。