Synergic effects of Si and V micro-additions on microstructural and mechanical properties of a dilute Al-Sc-Zr alloy containing L12 Al3(Sc, Zr, V) nanoprecipitates

This study investigates the impact of incorporating 0, 0.05, 0.10 at% V into a bare Al-0.06Sc-0.06Zr-0.18Si at% alloy on the precipitation behavior of Al3(Sc, Zr, V) (L12-structure) nanoprecipitates and the consequent creep resistance of the alloy. Various techniques were used to obtain results, including Vickers microhardness, Electrical conductivity, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and tensile creep rupture testing. The findings show that the amount of V added affected the nano precipitate structures, precipitation kinetics, coarsening resistance, and creep resistance of the alloys. After isochronal aging to 425 degrees C (25 degrees C/1 h step), alloy V0.10 had a peak microhardness value of 603 & PLUSMN; 14 MPa. TEM revealed a microstructure with precipitate diameters ranging from 3 to 20 nm. The nanoprecipitates had a core shell structure with a Sc-enriched core, a Zr-enriched shell, and, in some cases, a V outer shell. The phenomenon of vanadium partitioning at the precipitate shells occurred due to the incremental influence of silicon, which enhanced the diffusion rate of Zr and V. While the alloy V0.10 had a lower steady-state strain rate than the Al0.06Sc-0.06Zr at% alloy at stresses below 16 MPa, it showed better creep resistance at stresses above 16 MPa. The threshold stress of the alloy V0.10 (10 MPa) was almost equal to that of the previously studied Al-0.06Sc0.06Zr at% alloy (12 MPa). These results can be explained by the fact that a variation in the lattice parameter of Al3(Sc, Zr, V) (L12) affects the ability of matrix dislocations to traverse the nanoprecipitates, even in the absence of measurable lanthanides.