First-principles Investigation on Formation Energy, Elasticity and Interfacial Properties of Refining Phase Al3(Zr, Sc) in Al Alloys

Microalloying is an important means for strengthening aluminum alloys. Sc has attracted much attention as a refiner for aluminum alloys. The addition of Zr and Sc in aluminum matrix can achieve better grain refinement, due to the formation of Al-3(Zr, Sc) refining phase in the aluminum matrix. Based on the first-principles density functional theory, the energy and elastic properties of Al-3(Zr, Sc) formed under different ratios of Sc/Zr were studied. Besides, the interfacial properties of Al-3(Zr, Sc) and Al matrix were also investigated. The results show that when Sc/Zr ratio is not higher than 1/3, the refining phase prefers to precipitate as Al-3(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 increase of Sc/Zr ratio to 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 reduce the cost of the alloy.