Corrosion Behavior of Zr–(Nb–)Al–Ni–Cu Glassy Alloys

Abstract

The melt-spun glassy Zr 60-x Nb x Al 10 Ni 10 Cu 20 (x = 0, 5, 10, 15, 20at%) alloys were found to exhibit a large supercooled liquid region (ΔT x ) exceeding 42K before crystallization. The largest ΔT x for the glassy alloys containing Nb reaches as large as 82K for the Zr 55 Nb 5 Al 10 Ni 10 Cu 20 alloy. The glass transition temperature (Tg) increases and the ΔT x value decreases with increasing Nb content. The corrosion behavior of the Zr-(Nb)-Al-Ni-Cu glassy alloys was examined by mass loss (=weight loss) and electrochemical measurements. In IN HCI solution at 298 K, the addition of Nb for replacing some portion of Zr is effective in improving the corrosion resistance of the investigated Zr-based glassy alloys. The corrosion rate significantly decreases with increasing Nb content. The pitting potential and open circuit potential rise with Nb content. In 3%NaCl solution, the addition of Nb effectively increases the pitting potentials of the glassy alloys. In IN H 2 SO 4 solution, the corrosion rates of the glassy alloys are 10 -4 ∼ 10 -3 mm.y -1 (1 mm.y -1 = 0.317 pm.s -1 ). They are spontaneously passivaled and have a wide passive region with significantly low passive current density. The open circuit potential increases with an increase in Nb content.