Effect of Ni-Mg on the microstructure and properties of Al-(4-5)Fe-1V-1Si alloys

The paper deals with solidification behaviour, microstructure and mechanical properties of Al-(4-5)Fe-1V-1Si alloys. The alloys are prepared in a resistance-heating furnace and cast in a permanent mould at a cooling rate of 30 K/s. The solidification proceeds through several invariant reactions irrespective of treatment. The melt is treated with Ni-Mg master alloy in order to change the morphology, size and distribution of the primary as well as interdendritic phases. The treated alloys show an increase in first invariant reaction temperature and decrease in final invariant reaction temperature when compared with untreated alloy. With increasing amount of Ni-Mg master alloy addition the temperature of the first invariant reaction further increases and the final invariant reaction temperature decreases, probably due to action of grain refinement and phase modification. In comparison to untreatable alloy, appreciable improvement in mechanical properties occurs on modification by Ni-Mg treatment. Hot rolling further improves the mechanical properties of the alloy.