论文标题
Al-Li-Cu相图富含Al的角的第一原理分析
First-principles analysis of the Al-rich corner of Al-Li-Cu phase diagram
论文作者
论文摘要
富含AL的区域中Al-Li-CU系统的相图由第一原理计算和统计力学确定。通过密度功能理论模拟确定了整个Al-Li-CU系统中不同晶格的许多配置的混合焓，以在凸壳中找到稳定相。他们通过蒙特卡洛模拟拟合了群集扩展，以计算具有不同组成的构型的自由能（含量> 40 at。％）的温度函数。 It was found that the ground state phases in the Al-rich part of the Al-Li-Cu phase diagram were α-Al, θ' (Al2Cu), δ' (Al3Li), δ (AlLi) and T1 (Al6Cu4Li3), while θ'' (Al3Cu), T1' (Al2CuLi) and Al3Cu2Li were found on the lowest mixing enthalpy surfaces of their晶格，是亚稳态的。 α-AL，δ和T1是整个温度范围内的稳定相，而δ'在非常低的温度下变得可稳定，并且由于振动熵的贡献，在大约550 K处取代了θ'，作为稳定相。此外，构建了富含AL的区域的相图，并在等温部分中显示了从100 K到900K。它们与文献中有限的实验数据非常吻合，并提供了有关不同阶段的稳定性，溶解度和石学测定的新信息。此信息对于了解高温衰老期间的降水机制很重要。
The phase diagram of Al-Li-Cu system in the Al-rich region was determined by means of first-principles calculations and statistical mechanics. The mixing enthalpies of many configurations for different lattices in the whole Al-Li-Cu system were determined by density functional theory simulations to find the stable phases in the convex hull. They were fitted with a cluster expansion to calculate the free energy of the configurations with different compositions as a function of temperature in the Al-rich region (Al content > 40 at. %) by means of Monte Carlo simulations. It was found that the ground state phases in the Al-rich part of the Al-Li-Cu phase diagram were α-Al, θ' (Al2Cu), δ' (Al3Li), δ (AlLi) and T1 (Al6Cu4Li3), while θ'' (Al3Cu), T1' (Al2CuLi) and Al3Cu2Li were found on the lowest mixing enthalpy surfaces of their lattices and were metastable. α-Al, δ and T1 are stable phases in the whole temperature range while δ' becomes metastable at very low temperature and θ (Al2Cu) replaces θ' as the stable phase at approximately 550 K due to the vibrational entropic contribution. In addition, the phase diagram in the Al-rich region was built and it was shown in isothermal sections from 100 K to 900 K. They were in good agreement with the limited experimental data in the literature and provided new information regarding the stability, solubility and stoichiometry of the different phases. This information is important to understand the precipitation mechanisms during high temperature aging.
