Effect of Zr addition on the glass-forming ability and mechanical properties of Ni–Nb alloy

The effect of zirconium (Zr) addition on the glass-forming ability (GFA) and mechanical properties of the Ni_61.5Nb_38.5 alloy has been studied. The addition of Zr improves the GFA. When x = 5 for Ni_61.5Nb_38.5−xZr_x (in at.%) alloys, the alloy exhibits the best GFA and can be cast into 3-mm-diameter amorphous samples by using the copper mold injection-casting method. Differential scanning calorimetry measurements indicated that the thermal parameters, such as T_rg and γ, have not a good correlation with the GFA in the Ni–Nb–Zr alloys. Compression tests reveal that the addition of Zr just decreases the fracture strength slightly from 3.4 to 3 GPa and that all of the tested samples exhibit a little compressive plasticity of about 2%. When x = 9, the feature of the fracture surface indicates that the alloy has a tendency for transition from the ductile to the brittle. And delicate “dimple” and microscale vein pattern structures have been observed on it.