Improved thermal stability of nanostructured surface on Al 6082 alloy by (Zr+Yb) addition

Aluminum alloy 6082 (AA6082) is widely used in the production of industrial structural parts due to its light weight and good mechanical properties. However, such structural components are often accompanied by peripheral coarse grain defects and poor surface hardness and wear resistance. A nanostructured surface layer was developed on AA6082 through surface mechanical attrition treatment (SMAT) to improve the surface properties. Thermal stability and other features of nanostructured surface layer were investigated after annealing from 150°C to 350°C. The experiment results showed that the thermal stability for the surface nanostructure layer on AA6082 without containing (Zr+Yb) was at 300°C, while the composite addition of (Zr+Yb) improved the thermal stability for the surface nanostructure layer on AA6082 by 50°C and stabilized at 350°C. We found that the high thermal stability of surface nanostructure layer on AA6082 containing (Zr+Yb) was due to the pinning effect of the (Zr+Yb)-containing precipitates on the grain boundaries. The main objective of this study is to improve the surface performance of AA6082 by SMAT and to investigate a way to enhance the thermal stability of the surface nanostructure in order to qualify the material for various temperature service conditions.