Crystalline phases found in rapidly quenched Ni-Nb-Zr alloys

The properties of metallic alloys can be significantly improved by developing non-equilibrium phases in the microstructures through rapid solidification techniques, thus the characterisation of these unusual structures is extremely important. In this research, the microstructures of three rapidly quenched alloys, namely Ni_65.2 Nb_33.8 Zr_1.0 , Ni_54.8 Nb_31.1 Zr_14.1 and Ni_54.8 Nb_21.6 Zr_23.6 (at. %) were investigated in greater detail in order to determine the structures and compositions of their crystalline phases. These crystalline phases were characterised using a combination of scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction and transmission electron microscopy techniques. The phases were compared to the crystalline structures reported in the literature. Our results indicate some agreement with the Ni-Nb phase diagram and an isothermal section of the Ni-Nb-Zr phase diagram; however, it is detected zirconium solubility in the Ni₃ Nb phase, as well as, the absence of expected crystalline phases.