Binary bulk metallic glass Ni62Nb38 with high compressive strength of 3100MPa

Formability and mechanical properties of Ni62Nb38 binary bulk metallic glass were investigated in this study. Ni62Nb38 glassy rods were prepared by copper mold suction casting with a critical diameter larger than 2mm. The glassy rod exhibits typical amorphous characteristics in X-ray diffraction patterns, differential scanning calorimetry traces and high-resolution electron microscopic images. The formability of the alloy was investigated by means of the reduced glass transition temperature, the parameter gamma and the fragility parameter m, respectively. From the fragility parameter, it can be deduced that Ni62Nb38 binary alloy can be considered as a better glass former. Also, the alloy has a higher elastic moduli because of its higher value of Tg and slightly lower value of m than most of other BMGs. Nano-indentation and compressive testing results have proved that the glassy rod exhibits the highest Young's modulus of 231GPa and fracture strength of 3.1GPa among binary BMGs. The fracture mechanism of Ni62Nb38 glassy rod was investigated via the compressive stress-strain curve and the fracture surface morphology.