Thickness-dependent Strengthening Effect of Grain Refiner Al3Zr and Al3(Zr,Sc) in Al Alloys

Abstract

Grain refinement is an effective means to optimize the properties of the alloy. Al3Zr, Al3Sc and Al3(Zr,Sc) phases have attracted much attention as effective grain refiners for aluminum alloys, and their precipitation size will directly affect their interfacial strengthening effect with the matrix. In this paper, the first-principles method has been used to construct the Al/Al3Zr/Al double interface crystal model with different thicknesses of Al3Zr. The strengthening effect of the phase Al3Zr on the matrix during the precipitation growth process is described, and the optimal precipitation thickness of the strengthening phase Al3Zr is determined. By calculating the Griffith separation work and stress-strain curves of the interfaces between the refining phases with different thicknesses and the aluminum matrix, the change trend of the strengthening effect on the Al/Al3Zr/Al interface during Al3Zr precipitation growth is analyzed from the perspective of the combination of static and dynamic interface strength. Then the interfacial strengthening effect of the Sc-doped Al3(Zr,Sc) phase to Al matrix is analyzed. The electron density difference is used to analyze the interfacial bonding characteristics from the perspective of electronic bonding.