Effect of samarium modification on the microstructures evolution and mechanical properties of high strength aluminum alloy

Abstract

High strength aluminum alloys have been used in various industries, but increasing the strength and ductility of the alloy simultaneously remains a challenge. To solve this problem, a novel Al-Zn-Mg-Cu-Zr( Sm) alloy with Sm addition was prepared. The results show that the Sm element exists in the form of Al 10 Cu 7 Sm 2 phase, with a small amount distributed in the matrix and eutectic phases. After Sm modification, the recrystallization behavior was inhibited, and the substructure and deformation microstructure in the extruded alloy were improved. Moreover, Sm can effectively promote the formation of η’ phase and inhibit the conversion of η’ phase to η phase. Based on the above factors, the strength of the alloy was improved. Meanwhile, for the modified alloy, grain refinement reduces crack nucleation and finely dispersed precipitates reduce stress concentration, which is also responsible for the increased ductility of the alloy. • The effect of different Sm content on the microstructure of Al-Zn-Mg-Cu-Zr alloy was studied. • Sm in Al-Zn-Mg-Cu-Zr alloy mainly exists as Al 10 Cu 7 Sm 2 intermetallic compound, and a small amount is dissolved in the matrix and eutectic phase. • Sm can inhibit the recrystallization behavior of the alloy and promote the precipitation of η’ phase. • When the Sm content is 0.3%, the alloy has higher strength and toughness. • Mechanism of tensile fracture and alloy strength and toughness improvement is discussed.