Influence of rapid solidification on the microstructure and mechanical properties of NiAl-Based near eutectic alloys

The effects of rapid solidification on the microstructure and mechanical properties of two kinds of NiAl based eutectics were investigated. Rapid solidification resulted in the following effects, which encompass the refinement of the cell size, lamellar spacing and precipitates, deviation from the equilibrium composition, solubility extension, and a transition from a Heusler phase to an Hf-rich solid solution phase. Except for the deviation from the equilibrium composition, these microstructural characteristics are all beneficial to the improvement of mechanical properties. As a consequence, the room temperature compression yield strength and compression ductility were improved significantly and high temperature strength improved slightly. The high temperature compressive flow behaviour can be described by the temperature-compensated power-law equations.