核壳结构纳米相析出的第一性原理界面热力学-中国材料进展

文章信息/Info

Title:: First-Principles Interface Thermodynamics of Core-Shelled Nano-Phase Precipitation in Alloys

Author(s):: JIANG Yong; ZHANG Chaomin; (1. School of Materials Science and Engineering, Central South University, Changsha 410083, China) (2. National Key Laboratary for Powder Metallurgy, Central South University, Changsha 410083, China)

Keywords:: Al-Sc-Zr; Al-Er-Zr; L12 phase; core-shelled structure; interface; first principles

摘要:: 纳米析出相结构的热稳定性对于提升合金的服役温度意义重大。本文选择以稀土(RE)铝合金为例，采用第一性原理计算研究了共格L12型纳米析出相的界面偏聚、界面应变和界面形成能等。基于传统形核理论和第一性原理能量学计算结果，进一步预测评估了在等溶质原子比和给定时效温度条件下，各种可能的纳米析出相结构的析出热力学及其相对稳定性，包括二元析出相L12-Al3X (X=Sc/Zr/Er)以及具有不同复合结构的三元析出相L12-Al3(ErxZr1-x)和L12- Al3(ScxZr1-x)。对以上结果的讨论分析，可以充分确定核壳结构L12型纳米析出相在铝合金中的热稳定性优势，并能够从机理上解释文献中多样性的实验观察结果。

Abstract:: The thermal stabilities of nano-precipitates are critical in determining the service temperature of metallic alloys. Taking the Al-RE (rare earth) alloys as an exemplary case, we performed intensive first-principles calculations on solute segregation, coherent strains, and formation energies of L1₂-phase nano-precipitate interfaces. Based on the classic nucleation theory, the first-principles energetics results were further employed to evaluate the precipitation thermodynamics and relative stabilities of various possible structures of L1₂ nano-phases, including binary L1₂-Al₃X (X=Sc/Zr/Er) and various complex structured ternary L1₂-Al₃(Er_xZr_1-x) and L1₂-Al₃(Sc_xZr_1-x), under a certain aging temperature with an equi-atomic ratio of RE solutes. Finally, all the results were combined to establish the thermal stability advantage of core-shelled L1₂nano-phases in Al alloys, which can provide the fundamental understanding of diverse experimental observations in the literatures.