Microstructure, high-temperature compressive and tensile deformation, and corrosion property of multi-phase alloys based on Ni3Al-Ni3Ti-Ni3Nb pseudo-ternary alloy system were investigated. The microstructures of these alloys were largely dependent on alloy composition but independent of annealing temperature. Alloys composed of multi-phase microstructures of L1(2), D0(24) and D0(a) showed substantially enhanced compressive yield stress as well as a certain amount of compressive plasticity at whole temperature, while they did not show reasonable tensile elongation at whole temperature. Also, alloys composed of lamellar-like multi-phase microstructures are effective in enhancing compressive yield stress particularly at high temperature. Multi-phase alloys with low Nb contents have good corrosion resistance, especially in high concentration of sulfuric acid. (C) 2004 Kluwer Academic Publishers.