Effects of minor Sc addition on the microstructure and mechanical properties of 7055 Al alloy during aging

This study investigated the effects of 0.25% (mass ratio) Sc addition on the microstructure and mechanical properties of 7055 alloy during aging. Sc addition induced a grain boundary effect, which refined the grains of the 7055 alloy. Sc addition also increased the precipitation nucleation efficiency and promoted the uniform precipitation of the η′ phase of 7055 alloy during aging. Compared with pure 7055 alloy, 7055 alloy with Sc exhibited improved hardness, tensile strength, ductility, and thermal stability. This improvement was attributed to the finer size, higher density, more uniformly distributed η′ phase, less η phase, and finer Al grains of 7055 alloy with Sc compared with those of 7055 alloy without Sc.