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Dimitri Eigel Leibniz-Institute for Solid State and Materials Research IFW Dresden, Dresden D-01171, Germany; and Department of Chemistry and Food Chemistry, Faculty of Science, TU Dresden, Dresden D-01069, Germany

Daniel Grell Materials Testing, University of Kaiserslautern, Gottlieb-Daimler-Straße, Kaiserslautern D-67663, Germany

Jürgen Eckertb) Leibniz-Institute for Solid State and Materials Research IFW Dresden, Dresden D-01171, Germany; and Institute of Materials Science, Faculty of Mechanical Science and Engineering, TU Dresden, Dresden D-01062, Germany

Eberhard Kerscher Materials Testing, University of Kaiserslautern, Gottlieb-Daimler-Straße, Kaiserslautern D-67663, Germany

Annett Gebert Leibniz-Institute for Solid State and Materials Research IFW Dresden, Dresden D-01171, Germany (Received 20 August 2014; accepted 11 November 2014)

Five well-known Zr-based alloys of the systems Zr–Cu–Al–(Ni–Nb, Ni–Ti, Ag) (Cu 5 15.4–36 at.%) with the highest glass-forming ability were comparatively analyzed regarding their pitting corrosion resistance and repassivation ability in a chloride-containing solution. Potentiodynamic polarization measurements were conducted in the neutral 0.01 M Na2 SO4 1 0.1 M NaCl electrolyte and local corrosion damages were subsequently investigated with high resolution scanning electron microscopy (HR-SEM) coupled with energy dispersive x-ray spectroscopy (EDX). Both pitting and repassivation potential correlate with the Cu concentration, i.e., those potentials decrease with increasing Cu content. Pit morphology is not composition dependent: while initially hemispherical pits then develop an irregular shape and a porous rim. Corrosion products are rich in Cu, O, and often Cl species. A combination of low Cu and high Nb or Ti contents is most beneficial for a high pitting resistance of Zr-based bulk metallic glasses. The bulk glassy Zr57Cu15.4Al10Ni12.6Nb5 (Vit 106) and Zr52.5Cu17.9Al10Ni14.6Ti5 (Vit 105) alloys exhibit the highest pitting resistance.

I. INTRODUCTION

Among the various families of bulk metallic glasses (BMGs), the Zr-based alloys are until today most actively studied. The strong interest in Zr-based BMGs is due to their high glass-forming ability and excellent mechanical properties such as very high strength and large elastic deformation capability at room temperature. These qualities render them attractive for various applications, e.g., sporting goods, springs, or electronic casings.1 For most of those applications, a high corrosion resistance in various environments is mandatory for a long lifetime a)

Address all correspondence to this author. e-mail: [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/jmr-editor-manuscripts/. DOI: 10.1557/jmr.2014.371 J. Mater. Res., Vol. 30, No. 2, Jan 28, 2015

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of a part made from a BMG. Fabrication of bulk