Versatile fluidity test model for cast superalloys and comparison between IN718 and IN939

A spiral fluidity test model of superalloys with 10 mm in height and 3 mm in thickness was designed to evaluate the fluidity of two distinct Ni-based superalloys IN718 and IN939. The factors influencing fluidity are ascertained through comparative analysis utilizing methodologies such as JMatPro, differential scanning calorimetry and high-temperature confocal laser scanning microscopy. The results show that under identical testing conditions, the fluidity of the IN939 superalloy surpasses that of the IN718 superalloy. When subjected to the same temperature, the melt viscosity and surface tension of IN939 superalloy are considerably reduced relative to those of IN718 superalloy, which is beneficial to improving the melt fluidity. Furthermore, the liquidus temperature and solidification range for the IN939 superalloy are both smaller compared with those of the IN718 superalloy. This condition proves advantageous in delaying dendrite coherency, thereby improving fluidity.