Microstructural Feature and Evolution of Rapidly Solidified Ni3Al-Based Superalloys

The Ni3Al-based superalloy was rapidly solidified in the form of droplets with varying diameters. The cooling rate (R-c) is a function of diameter (D) of droplet. With the decrease in droplet sizes (increase in the cooling rates), the volume fraction of + eutectic structure increases from 21.31 (D=1400m, R-c=3.6x10(2)Ks(-1)) to 36.31% (D=270m, R-c=2.3x10(3) Ks(-1)). Moreover, unimodal size distribution of nano- exists in the droplets instead of bimodal dual-size distributions of precipitates that are normal in as-cast alloys.