The Growth of .GAMMA.' Precipitates in a 53Ni-20Co-15Cr Superalloy.

Abstract

The age hardening behavior and microstructural characteristics of a 53Ni-20C0-1 5Cr-5Mo~L9Al-

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

“…(9) [22,23]: mined from regression analysis of Fig. The Q value of the alloy was compared well with that reported by Kusabiraki et al [20] for Incoloy 909 superalloy. From the linear regression analysis of the data, the activation energy of the undeformed and the 50 % cold deformed alloy was determined to be 262 and 254 kJ · mol -1 , respectively.…”

“…In this context, Kusabiraki et al [20] have displayed the gamma' precipitation and growth mechanism in the Incoloy 909 superalloy. In this context, Kusabiraki et al [20] have displayed the gamma' precipitation and growth mechanism in the Incoloy 909 superalloy.…”

Morphological changes of γ′ precipitates in superalloy IN738LC at various cooling rates

“…It was found that point density of primary ␥ was almost constant for all of the cooling rates but as the cooling rate decreased, primary ␥ decreased in size and volume fraction. For very high cooling rates the nucleation of new precipitates is expected to be low and even could be suppressed [20] and the partially dissolved primary precipitates can grow in the supersaturated matrix during the cooling period. But at lower cooling rates, nucleation of the new precipitates takes place, supersaturation in the matrix is reduced and the growth of the existing precipitates becomes restricted.…”

Analysis of the Precipitation and Growth Processes of the Intermetallic Phases in an Fe-Ni Superalloy

“…Values of the mean diameter of the particles D for the aging time of 0.5 h and 2 h were determined through extrapolation ( Figure 24). The activation energy of coagulation of the γ' -Ni 3 (Al, Ti) phase in the Fe-Ni alloy was determined from the slope of Arrhenius straight line ( Figure 25) and its value (E = 297 kJ/mole) turned out to be close to that of the activation energy of phase γ' (245-298 kJ/mole), which was estimated for the chosen Fe-Ni and Ni-based superalloys [36,37]. Moreover, the obtained value of phase γ' coagulation activation energy was close to that of the activation energy of diffusion in austenite of the solute elements, such as Al, Ti, Ni, Fe, Cr, and Mo, which contribute to the growth of phase γ'.…”

“…Based on the results from the obtained dependencies, the highest growth rate of the γ' phase particles was found at an aging temperature of 780°C, the medium rate at 750°C, and the lowest at 715°C. The analysis of the γ'-Ni 3 (Al,Ti) phase growth step was made on the basis of the LSW theory [34,35] for coagulation on volume diffusion control according to the relationship provided by Kusabiraki et al [36,37]:…”