Ductility enhancement in NiAl (B2)-base alloys by microstructural control

An attempt to improve ductility of NiAl (B2)-base alloys has been made by the addition of alloying elements and the control of microstructure. It has been found that a small amount of fccγ phase formed by the addition of Fe, Co, and Cr has a drastic effect not only on the hot workability but also on the tensile ductility at room temperature. The enhancement in ductility is mainly due to the modification of Β-phase grains by the coexistence ofγ phase. The effect of alloying elements on the hot forming ability is strongly related to the phase equilibria and partition behavior amongγ,γ′ (L1₂ structure), and Β phases in the Ni-Al-X alloy systems. The ductility-enhancement method shows promise for expanding the practical application of nickel aluminide.