In situ investigation on the precipitation of topologically close-packed phase in Ni-base single crystal superalloy

In situ transmission electron microscopy (TEM) investigations reveal the homogeneous nucleation of topologically close-packed (TCP) phase in Ni-base single crystal superalloy at elevated temperatures, which tends to grow toward primary γ/γ′ interface for element supply. Ru addition can decrease both the nucleation and growth rate, hence to suppress TCP precipitation effectively. Higher exposure temperature reduces the nucleation rate but increases the growth rate, finally accelerates the TCP precipitation.