Effect of minor addition of vanadium on mechanical properties and microstructures of as-extruded near eutectic Al-Si-Mg alloy

Mechanical properties of near eutectic Al-12.5 wt%Si-0.6 wt%Mg alloys with and without addition of V were tested. Results show that addition of 0.1 wt% V only has a minor influence on the tensile properties of near eutectic Al-Si-Mg alloy in as-cast and as-homogenized conditions. However, it can significantly improve the tensile properties in as-extruded condition. The YS is enhanced nearly 50% and the elongation can reach 14%. Three factors that may contribute to the enhancement of YS were analyzed by EBSD, XRD and TEM investigation, i.e. Δσgb (the strengthening from (sub-) grain boundaries), M (Taylor factor) and τtot (critical resolved shear stress). Results show that the higher τtot in the alloy with V addition is the main contributor to the higher YS. According to the TEM observation and EDX analysis, the fine precipitates contributed to the higher τtot in 4# alloy are quaternary AlFeVSi phases.