In this study, a demonstration of the effect of Na addition to the
microstructure and wear rate of hypereutectic Al-14 wt% Si alloy was carried out. It is
found that the addition of Na has an important effect on shifting the eutectic
composition of Al-Si alloys from approximately 12 wt% to 14 wt% Si; shifting the
unmodified alloy from hypereutectic to eutectic alloys for the modified alloys. The
modified alloys have a eutectic composition with fine needle at lower Na content
(0.05 wt%). Increasing the percentage of Na to 0.12 wt% resulted in producing a
lamellar Si structure compared with acicular structure for unmodified alloy. The wear
rate of modified alloys is lower than the hypereutectic alloy. Wear rates observed
were in the range of 10-9 to 10-11 which is fully identified in the mild wear rate regime.