Abstract Four kinds of Al-Zn-Mg-Cu alloys adding Yb, Zr, Ti were prepared by cast metallurgy. Effects of Yb-Zr, Zr-Ti, Yb-Ti, Yb-Zr-Ti additions on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloy were compared by optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), hardness and tensile test. The results show that, the Al-Zn-Mg-Cu alloy with Yb-Ti additions forms obvious subgrain boundaries during hot extrusion. After solution treatment, the alloys with Yb-Ti and Zr-Ti additions have obvious recrystallization. The alloys with Yb-Zr and Yb-Zr-Ti have obvious effect of restraining recrystallization due to the precipitation of a large number of coherent Al3(Zr,Yb) dispersed phases with size of 10-20 nm. Micron-sized Al8Cu4Yb and Al20Ti2Yb phases are precipitated in Al-Zn-Mg-Cu alloy with Yb-Ti addition, which induce the matrix recrystallization. Al-Zn-Mg-Cu-Yb-Zr alloy without recrystallization has the highest mechanical properties and fracture toughness, the ultimate strength, yield strength, elongation and fracture toughness are 721.9 MPa, 711.5 MPa, 9.7 %, 29.3 MPa·m1/2, respectively, and exhibits complete dimple fracture characteristics. The mechanical properties of Al-Zn-Mg-Cu-Yb-Ti alloy with complete recrystallization are the lowest, and the fracture mode is complete intergranular fracture.
FANG Huachan,ZHU Jiamin,CHEN Zhuo, et al. Effect of Yb, Zr, Ti additions on the microstructure and mechanical properties of super-high strength Al-Zn-Mg-Cu alloys[J]. Materials Science and Engineering of Powder Metallurgy, 2019, 24(2): 176-187.
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2019, Vol. 24 
