Effects of Sc addition on microstructure, mechanical and corrosion resistance properties of 7055 Al alloy

Abstract

This research investigates the influences of different contents of Sc on the microstructure, mechanical, electrical conductivities and corrosion resistance properties of 7055 alloy. The effect of Sc can increase the non-uniform nucleation of the alloy and significantly refine the casting structure of the alloy. In addition, the addition of Sc not only inhibits grain coarsening, pins GBs and restrains recovery and recrystallisation, but also maintains the effect of fibre structure during the formation of high-density nano-Al3 (Sc, Zr) phase precipitation. Compared with pure 7055 alloys, the hardness, tensile strength, elongation, electrical conductivity and corrosion resistance of 7055 alloys with Sc are improved remarkably. After adding a little Sc, the grain size of the alloy is refined from 80um to 40um, and the properties of the alloy are improved. When Sc content is 0.25%, the tensile strength of the alloy increases from 623.1mpa to 685.9mpa, and the self-etching current density decreases from 1.56 × 10−5 to 8.74 × 10−7, and the corrosion resistance is also greatly improved.