The ductility of Ni3Al macro-alloyed with a γ former and a γ′ former was examined on the basis of the assumption that lowering of ordering energy was responsible for ductility improvement of macro-alloyed Ni3Al. It was found that the addition of γ formers such as palladium, platinum copper and cobalt improved the ductility of Ni3Al, whereas alloys containing γ′ formers such as tantalum, molybdenum, niobium, zirconium, vanadium, titanium and silicon remain brittle. In addition, observations of antiphase domain structures in melt-spun ribbons of macro-alloyed Ni3Al revealed that the addition of γ formers effective in ductilizing lowered the ordering energy of Ni3Al, whereas that of γ′ formers ineffective in ductilizing raised the ordering energy of Ni3Al. It was concluded that the addition of a ternary element lowering the ordering energy of Ni3Al was strongly associated with the ductilization of Ni3Al.

Improvement in Ductility of Ni3Al by γ Former Doping. Chiba, A., Hanada, S., Watanabe, S.: Materials Science and Engineering A, 1992, 152[1-2], 108-13