Nucleation Crystallography of Ni Grains on CrFeNb Inoculants Investigated by Edge-to-Edge Matching Model in an IN718 Superalloy

In this work, the nucleation crystallography of CrFeNb intermetallic particles as a grain refiner for Ni-based IN718 superalloys is studied using Edge-to-Edge Matching model. Three distinguishable orientation relationships between CrFeNb intermetallic particles and Ni grains are well predicted: [110]_Ni//[1210]_CrFeNb, (111)_Ni 1.28° from (0004)_CrFeNb, [110]_Ni//[1210]_CrFeNb, (111)_Ni 1.32° from (2020)_CrFeNb, and [110]_Ni//[0001]_CrFeNb, (111)_Ni 0.72° from (2020)_CrFeNb. The results indicate that CrFeNb intermetallic particles have a strong nucleation potency as an effective grain refiner for Ni-based superalloy and the existence of semi-coherent interfaces between the CrFeNb intermetallic particles and Ni grains. Furthermore, the IN718 superalloy is used to experimentally validate the grain refinement effect of CrFeNb intermetallic particles, showing that its grain size is obviously refined from 8.60 to 1.23 mm. And, the corresponding heterogeneous nucleation mechanism of grain refinement at the atomic level is further identified.