<p>The purpose of the present research was to choose the appropriate method for vacuum investment casting of precipitation hardened nickel-based superalloys. Two types of casting systems were designed. In the first, the superalloy melt entered the mold from the bottom with an ingate velocity of about 0.3&#xa0;m/s. In the other one, the melt was poured from the top into the mold. Casting superalloys produced by these two methods were subjected to various microstructural and mechanical properties tests. The results showed that filling the mold from the top or bottom and controlling the ingate-velocity have no significant effect on the microstructural characteristics and mechanical properties of the alloy. It was thermodynamically and kinetically demonstrated that the solid oxide layers formed on the surface of molten superalloy during the vacuum investment casting process are quickly deoxidized/reduced by aluminum in the superalloy composition. Therefore, the effective amounts of oxide-bifilms are not formed in superalloy castings during vacuum investment casting.</p> Graphical Abstract <p></p>