铝合金细化相Al3(Zr,Sc)的能量和弹性性质的第一性原理研究

Theoretical Investigation on Formation Energy and Elastic Properties of Refining Phase Al3(Zr, Sc) in Al Alloys

摘要:

微合金化是强化铝合金的重要手段，Sc作为铝合金有效的细化剂而引起广泛关注。实验研究表明，在铝基体中同时添加Zr和Sc，在铝基质中形成Al3(Zr,Sc)细化相，可以实现更好的晶粒细化。本文基于密度泛函理论的第一性原理方法，系统地研究了不同Sc/Zr配比下形成的Al3(Zr,Sc)细化相的能量和弹性性质。结果表明，当Sc/Zr不高于1/3时，Al3(Zr,Sc)相具有较大的形成焓绝对值，细化相将优先于Al3(Zr,Sc)相析出。同时，Sc元素的加入有利于界面的形成，提高界面的结合强度和润湿效果，但高于1/3的Sc/Zr比对界面性能的提高并无积极作用。并且，Zr的加入可以有效提高细化相的弹性性能，并削弱Al3Sc的弹性各向异性特征。此理论研究指出，微合金化Zr和Sc的共同添加时Sc/Zr不高于1/3时，可以保证细化效果并大大降低合金的成本。

Abstract:

Microalloying is an important means of strengthening aluminum alloys. Sc has attracted much attention as a refiner for aluminum alloys. Experimental studies have shown that the addition of Zr and Sc in aluminum matrix can achieve better grain refinement, which is due to the formation of Al3(Zr, Sc) refining phase in the aluminum matrix. Based on the first-principles density functional theory, the energy and elastic properties of Al3(Zr, Sc) formed under different ratios of Sc/Zr are systematically studied. Besides these, the interfacial properties of Al3(Zr, Sc) with Al matrix are also investigated. The results show that when Sc/Zr is not higher than 1/3, the refining phase prefers to precipitate as Al3(Zr, Sc) based on its larger absolute value of formation enthalpy. And the addition of Sc element is also beneficial to the formation of the interface and the improvement of the interface bonding strength with better wetting effect, but the excessive increasing of Sc/Zr ratio higher than 1/3 shows no positive effect on the improvement of the interface performance. Additionally, the co-addition of Zr and Sc can improve the elastic properties and weaken the anisotropy of Al3Sc while greatly reducing the cost of the alloy.