Mechanical properties of dual multi-phase single-crystal intermetallic alloy composed of geometrically close packed Ni 3X (X: Al and V) type structures

Abstract

Dual multi-phase intermetallic alloy, which is composed of Ni 3Al(L1 2) and Ni solid solution (A1) phases at high-temperature annealing and is additionally refined by a eutectoid reaction at low temperature aging, according to which the Al phase is transformed into the Ni 3Al(L1 2) + Ni 3V(DO 22) phases, was prepared based on the pseudo-ternary system Ni 3Al–Ni 3Ti–Ni 3V. The high-temperature tensile deformation, fracture behavior and tensile creep were investigated using single crystalline material. The alloy with such a novel microstructure shows extremely high yield and tensile strength with good temperature retention, when compared not only with conventional Ni-based superalloys but also with polycrystalline materials reported previously. Over a broad temperature range fracture occurred along octahedral plane in the major component L1 2 phase, accompanied with high tensile elongation and ductile fracture mode. The tensile creep test conducted at 1173 K and 1223 K showed the presence of threshold stress, and also extremely low creep rate and long creep rupture time when compared with conventional Ni-based superalloys. The obtained results are promising for the development of a new-type of high-temperature structural material.