In situ TEM investigation on the precipitation behavior of μ phase in Ni-base single crystal superalloys

In situ transmission electron microscopy (TEM) investigations reveal the layer-by-layer growth mechanism of μ phase precipitated in Ni-base single crystal superalloys. Three types of μ phase with different morphologies were formed at 1050 °C, which grows along [001]μ with (001)μ planar defects, [-111]μ with (1-12)μ planar defects, as well as both directions with mixed planar defects respectively. Formation of (001)μ micro-twin and stacking fault is the essential feature for precipitated μ phase, while nucleation of incoherent (1-12)μ planar defects plays an important role in changing growth method.147