ABSTRACT
Eutectic Al–13 wt. % Si and hypereutectic Al-16 wt. % Si were prepared by using
permanent mould casting technique. Effect of the cooling technique on the cast
microstructure, mechanical properties, and electrical conductivity of Al-Si alloys was
investigated by using the conventional water-cooled and air-cooled methods. The
mechanical properties such as the yield stress, tensile strength, hardness, and
impact energy were measured at various cooling methods. Microstructure with
scanning electron microscope (SEM) and Energy dispersive spectrometer (EDS)
analysis of Al-Si alloys have been studied. In addition, the hardness after solution
treatment at 529 °C for 2 h and artificial ageing at various temperatures 180 °C and
210° C for aging time 2- 10 h was measured. The results show enhancement in the
mechanical and electrical properties for the eutectic Al-13 wt. % Si and hypereutectic
Al-16 wt. % Si alloys for the water-cooled over the air-cooled technique. In addition,
the largest value of the impact energy (4.91 J) was obtained for the eutectic Al-13 wt.
% Si alloys compared to the hypereutectic Al-16 wt. % Si alloys at 3.09 J for watercooled-
medium. The total solidification time (TST) of Al 13% wt. Si was longer than
that time for the hypereutectic Al 16% wt. Si at various cooling mediums. Aging
studies of Al-Si alloys with aging temperatures 180 ºC and 210 ºC show that the
hardness values increased as the silicon content increases. For hypereutectic Al-16
wt. % Si at aging temperature 180 ºC and aging time 4 h by using water-cooled
technique, it was observed that the maximum hardness value reached to 100 HRD
compared that value was 87 HRD for the eutectic Al-13 wt. % Si alloy.