Ductility of Ni₃Al doped with substitutional elements

This paper reports on ductility of B-free Ni₃Al alloys. Recrystallized Ni₃Al binary alloys with Ni-rich compositions show appreciable ductility when an environmental effect is eliminated, while the alloys with stoichiometric and Al-rich compositions remain brittle. The ductility in the Ni-rich Ni₃Al alloys is associated with low ordering energy. The additions of ternary elements, which are classified as γ formers, ductilize ternary Ni₃Al alloys(Ni-23 at%Al-2 at%X, X=Pd, Pt, Cu and Co), whereas the additions of γ′ formers embrittle ternary Ni₃Al alloys(Ni-23 at%Al-2 at%X, X=Ta, Mo, Nb, Zr, Hf, V, Ti and Si). The additions of small amounts (less than 1 at%) of γ′ formers such as Zr and Hf also ductilize as-cast ternary Ni₃Al alloys. Ductility of Ni₃Al alloys doped with substitutional elements is discussed in terms of ordering energy and microstructure.