The microstructures and mechanical properties of Ni-（46-x）Ti-4Al-xZr （x = 0-8, at.%） alloys have been investigated by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and mechanical tests. The results show that the Ni-Ti-Al-Zr alloys are composed of TiNi and （Ti, Al） 2 Ni with Zr as a solid solution element in both phases, and the third phase, （Zr, Ti, Al） 2 Ni, appears in Ni-40Ti-4Al-6Zr and Ni-38Ti-4Al-8Zr alloys. The compressive yield strength at room temperature increases with the increase of Zr content due to the solid-solution strengthening of Zr and precipitation strengthening of （Ti, Al, Zr） 2 Ni phase. However, the Ni-42Ti-4Al-4Zr alloy exhibits the maximum compressive yield strength at 873 and 973 K because of the softening of （Zr, Ti, Al） 2 Ni phase in the alloys with more Zr addition. The tensile stress-strain tests and the SEM fracture surface observations show that the brittle to ductile transition temperature of Ni-42Ti-4Al-4Zr alloy is between 873 and 923 K.
