Precipitation Behavior of Spherical γ′ Phase in Eutectic Area of Ni3Al-Based Alloy

Understanding and mastering initial status in eutectic area (gamma '-gamma) of Ni3Al-based alloy under solution treatment conditions are beneficial to its aging treatment and applications. In this work, optimal solution treatment process parameters of JG4246A Ni3Al-based alloy are investigated based on microstructure observation, chemical composition analysis, and micro-hardness test. Results show that the alloy with solution temperature of 1270 degrees C for 6 h possess smoother eutectic area (gamma '-gamma) boundaries, more stable carbides, and relatively higher micro-hardness. More importantly, to clarify the evolution behavior of Ni3Al (gamma ') phase in eutectic area (gamma '-gamma) under solution treatment conditions, short-time (3 h) and long-time (18 h) solution treatments at 1270 degrees C are applied and the evolution behavior is analyzed by TEM. Results show that plenty of spherical Ni3Al (gamma ') phase appears in eutectic area (gamma '-gamma), with its dimensions changing little with solution time increasing. Vacancies, lattice distortion, and thermo-stress mainly contribut to the precipitation and growth of spherical Ni3Al (gamma ') phase.