ACTA PHYSICA POLONICA A, cilt.135, ss.884-887, 2019 (SCI İndekslerine Giren Dergi)
In this study, comparatively microstructure and hardness properties of AZ91 alloy with the addition of 1.95 wt% silicon were investigated by using ceramic mold. For this purpose, the alloys were provided to solidfy in different rates due to using that mold. Alloys cast into this mold showed rapid cooling behavior due to copper in the base, while cooling rate decreased on the top zone. The results showed that alpha+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 with 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.