Metastable phases found in the Ni-Nb-Zr system

Abstract

The development of metastable phases in the microstructures from rapid solidification techniques could significantly improve the properties of metallic alloys, thus it is extremely important the characterization of these unusual structures. In this research, the microstructure of a rapidly-quenched alloy, namely Ni61.6Nb33.1Zr5.3 (at.%) was investigated in greater detail in order to determine the structures and compositions of their crystalline phases. These crystalline phases were characterized using a combination of the following techniques: scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and x-ray diffraction. The phases were compared to the crystalline structures reported in the literature. Our results indicate a high solubility of niobium into Ni10Zr7 and Ni21Zr8 crystalline structures and consequently suggest the formation of two metastable phases in the Ni-Nb-Zr system.