Abstract: IN718 Ni-Fe-base alloy was prepared to study the effects of phosphorus. The results show that phosphorus improves morphology of grain boundary precipitates. Phosphorus has a remarkable beneficial effect on stress-rupture life and creep resistance. Increasing phosphorus in IN718 to 0.02\% causes an increase of the apparent creep activation energy from 678.6 kJ/mol to 746.1 kJ/mol. It has been proposed that the significant beneficial effect of phosphorus mainly arises from the inhibition of diffusion along grain boundary.

Key words: IN718 alloy, Phosphorus, Microstructure, Creep