Enhancing bulk metallic glass formation in Ni–Nb–Sn-based alloys via substitutional alloying with Co and Hf

Bulk metallic glasses have been formed over a fairly wide composition range (54–62 at.% Ni, 32–36 at.% Nb, and 3–11 at.% Sn) in the Ni–Nb–Sn ternary system. Partial substitution of Co for Ni and Hf for Nb improves the glass-forming ability, eventually leading to 4 mm glassy rods at the Ni56Co3Nb28Hf8Sn5 composition. The positive effects of these alloying elements have been explained based on a systematic monitoring of the amount and morphology of the competing crystalline phases as a function of the Co and Hf contents.