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。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)。通过对以上结果进行讨论分析,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。
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 L1 2 -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 L1 2 nano-phases, including binary L1 2 -Al 3 X ( X =Sc/Zr/Er) and various complex structured ternary L1 2 -Al 3 (Er x Zr 1- x ) and L1 2 -Al 3 (Sc x Zr 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 L1 2 nano-phases in Al alloys, which can provide the fundamental understanding of diverse experimental observations in the literatures.
作者
江勇
张朝民
JIANG Yong;ZHANG Chaomin(School of Materials Science and Engineering, Central South University, Changsha 410083, China;National Key Laboratary for Powder Metallurgy, Central South University, Changsha 410083, China)
出处
《中国材料进展》
CAS
CSCD
北大核心
2019年第8期748-758,747,共12页
Materials China
基金
国家磁约束核聚变能发展研究专项(2018YFE0306100)
