Study on the grain refinement of A356 alloy by Al-3 wt-% VN master alloy

A novel Al-3 wt-% VN master alloy, mainly consisting of alpha-Al and VN phases, was successfully prepared by stir casting. The grain refinement performance of the master alloy on A356 alloy was then investigated. The results showed that the alpha-Al grain size of A356 alloy refined by Al-3 wt-% VN master alloy was 350 +/- 95 mu m while that of A356 alloy treated by traditional Al-5Ti-B master alloy was 570 +/- 105 mu m. Moreover, for A356 alloy with Al-3 wt-% VN addition, the good grain refining efficiency did not fade significantly within 30 min. The effectiveness of grain refinement might be attributed to VN particles, which acted as the heterogeneous nuclei of alpha-Al grains. Owing to the refinement strengthening, the yield strength, ultimate tensile strength and elongation of A356 alloy were improved.