Nonequilibrium Grain Boundary Segregation of Phosphorus in Ni-Cr-Fe Superalloy

In virtue of Auger electron spectroscopy, the grain boundary concentrations of phosphorus in Ni-Cr-Fe superalloy are measured after solution treatment at 1180 °C for 45 min. The results show that a peak of phosphorus concentration occurs at about 180 min during isothermal ageing at 500 °C, and a maximum concentration of phosphorus appears also at about 500 °C for all specimens aged for 20 min at temperatures of 200, 400, 500, 700 and 800 °C. The results are analyzed with the laws of nonequilibrium grain boundary segregation. It is found from the analysis that peaks are related to critical time for nonequilibrium grain boundary segregation of phosphorus.