Understanding the Ni–Nb–Zr BMG composition from a binary eutectic Ni–Nb icosahedral cluster

The Ni–Nb–Zr bulk metallic glass composition was analyzed by our cluster-plus-glue-atom model using a eutectic-related binary cluster M-Ni6Nb6, M = 0.5Ni + 0.5Nb, which was derived from a eutectic phase Ni7Nb6 (Fe7W6 type). A composition formula [M-Ni6Nb4MZr]Ni3 was then proposed, where the combination of one M and one Zr atom had an almost equal atomic size as a Nb atom to be substituted for. Alloy rods with 3 mm in diameter were obtained using copper mould suction casting. XRD results showed that compositions [M-Ni6Nb5-xMZrx]Ni3, x = 0.76, 0.84, 0.92, 1, 1.08, 1.16 formed single glassy phases, conforming to the proposed formula.