The effect of phosphorus on the formation of grain boundary laves phase in high-refractory content Ni-based superalloys. (1st March 2019) - Antonov, Stoichko
Abstract: The effect of phosphorous on the microstructure of a powder-processed, high Nb-content, Ni-based superalloy was studied and compared to a P-free variant. The P-doped sample had a lower incipient melting temperature, forming a (Ni, Co, Cr, P)2 (Nb, Mo) laves phase along the grain boundaries. Transmission electron microscopy and atom probe tomography were used to identify the crystal structure, assess phase compositions, and determine any elemental segregation to phase boundaries. The results revealed strong partitioning of P to the laves phase and a slight Mo gradient towards the γ′ phrase. Finally, a simplified laves phase was successfully modeled via density functional theory calculations. Graphical abstract: