8thInternational Advances in Applied Physics and Materials Science Congress Exhibition, Muğla, Türkiye, 24 - 30 Nisan 2018, ss.118
In this study, comparatively microstructure and hardness properties of AZ91 alloy with the a ddition of 1.95 wt.% silicon were investigated by using ceramic mold. For this purpose, the alloys were provided to solidfy in different rates owing to use that mold. Alloys poured into this mold showed a rapid cooling behavior due to copper in the base, while cooling rate decreased on the top zone. The results showed that α+Mg main matrix phase is present in AZ91 structure, Mg-Al eutectic and Mg17Al12 intermetallic phases extending along grain boundaries were observed in the main matrix as well. As the cooling rate increases, the grain boundaries of Mg17Al12 intermetallic phases were increased. The Mg17Al12 phase at grain boundaries was partially fragmented by the addition of Si. Coarsen Mg2Si phases were also formed with the addition of 1.95 wt.% silicon. The hardness values were increased with the increasing of cooling rate and the addition of silicon.