Microstructure and room temperature compressive properties of holmium doped DS NiAl-Cr(Mo)-Hf eutectic alloy

Abstract The microstructure and mechanical property of a eutectic Ni-33Al-28Cr-5.94Mo-0.05Hf-0.01Ho (holmium) alloy fabricated by using directional solidification under two withdrawal rates (3 mm min – 1 and 10 mm min – 1 ) are presented. It is shown that a promising as-cast microstructure is formed under the higher withdrawal rate, which can be characterized by the refinement of eutectic cells as well as eutectic lamellae between the NiAl and Cr(Mo) phases within the cells. As a positive response to this, superior room temperature mechanical properties with yield strength of 1153 MPa and compressive strain of 37 % are obtained. Based on these investigations, the mechanism responsible is discussed.