An experimental study of the precipitation kinetics of pre-rolled Ni-Span-C 902 superalloy

Abstract

An experimental study of the precipitation kinetics of pre-rolled Ni-Span-C 902 superalloy In the present work, the effects of cold work and aging parameters on the microstructure and precipitation kinetics of Ni-Span-C 902 superalloy were studied. The solution treated alloy was cold-rolled to different deformations from 30 to 60 % followed by aging in the temperature range of 450 -850 8C for different times, from 10 2 to 10 5 seconds. The results showed that the 50 % cold-rolled alloy attained its maximum hardness by aging at 650 8Cfor10 5 seconds. This was concurrent with the fine distributed gamma' precipitates that appeared in the microstructure. By increasing temperature from 750 to 850 8C, overaging occurred due to the increase in gamma' particle size and the formation of epsilon-phase. The estimated activation energy of the precipitation reaction, based on Johnson-Mehl-Avrami-Kolmogorov analysis, was determined to be 254 kJ · mol -1 for the 50 % cold-rolled alloy.