Thermally induced interdiffusion and precipitation in a Ni/Ni<inf>3</inf>Al system

Published by Taylor & Francis. Ordered Ni3Al intermetallic precipitates constitute the main hardening sources of Ni-based superalloys. Here, we report the interdiffusion and precipitation behavior in a Ni/Ni3Al model system. The deposition of Ni3Al on a pure Ni layer at 500°C generated L12-structured γ’ (Ni3Al) precipitates, preferentially at the interface. After annealing at 800°C for 1 h, interdiffusion between Ni and Ni3Al layers occurred, and the γ’ precipitates that grew near the parent Ni/Ni3Al interface are ∼2.8 times larger in size than those formed in the matrix. Monte Carlo simulations indicate that vacancies preferentially diffuse along the Ni/Ni3Al interface, increasing the probability of precipitation.