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

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.

Key words:refining phase; formation energy; elastic property; interfacial property; Al3(Zr, Sc)