The effect of Zr addition in glass forming ability of Ni–Nb alloy system

The effect of Zr addition on glass forming ability (GFA) of Ni–Nb alloys has been investigated. Ni60Nb40−xZrx (x = 0–40) alloys were prepared by melt-spinning and injection-casting. Crystallization behavior of the alloys was studied by differential scanning calorimetry (DSC), differential thermal analyzer (DTA) and X-ray diffractometry (XRD). The GFA increased with the addition of Zr, thus, a rod with the diameter of 2 mm was obtained in Ni60Nb30Zr10 which has the highest reduced glass transition Trg value of 0.619 among the alloys investigated. When Zr content is more than 10 at.%, the GFA deteriorated significantly. The atomic structure of Ni–Nb–Zr alloys investigated by means of extended X-ray absorption fine structure (EXAFS), indicated presence of chemical inhomogeneity in the amorphous structure due to the positive mixing enthalpy between Zr and Nb.