LAUSR

Abstract While understanding the precipitation kinetics of gamma double prime (γ″) phase is of vital importance in Inconel 718 superalloy, kinetics studies by Johnson–Mehl–Avrami–Kolmogorov (JMAK) and thermoanalysis techniques have not been conducted so far, and hence, investigating the mechanism of γ″ formation deserves more attention. In response, in the present work, the precipitation kinetics of γ″ phase was studied by JMAK analysis based on the hardness measurements during aging and differential thermal analysis (DTA) during continuous heating. Average Avrami exponent of 0.64 was obtained, which was interpreted as precipitation on dislocations on the theoretical front. Moreover, the activation energy of precipitation (Q) was found to be close to the activation energy for the diffusion of niobium in the matrix, which was also confirmed by the Kissinger's plot obtained from DTA analysis. As a result, the present work contributes to the kinetics and mechanism of the γ″ phase formation.