Plastic Flow and Fracture of B2 NiAI-based Intermetallic Alloys Containing a Ductile Second Phase

Abstract

The use of NiAl as a structural material has been hindered by its lack of tensile ductility or toughness at room temperature. The operative flow and fracture mechanisms in monolithic NiAl leading to these poor low temperature properties are analyzed, demonstrating the need for ductile phase toughening. Progress in ductile phase reinforced intermetallics and NiAI-based materials are reviewed and the primary mechanisms involved in the flow and fracture of ductile phase reinforced alloys are clarified by recent investigations of directionally solidified NiAI-based materials. The mechanical behavior of these model alloys (Ni-30AI and Ni-30Fe-20AI (at%)) are discussed. The prospects for developing a ductile phase toughened NiAI-based alloy and the shortcomings presently inherent in these systems are analyzed. © 1991, The Iron and Steel Institute of Japan. All rights reserved.