Oxidation resistance of the supercooled liquid in Cu 50 Zr 50 and Cu 46 Zr 46 Al 8 metallic glasses
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Won Tae Kim Department of Optical Engineering, Cheongju University, Cheongju 360-764, Korea
Eun-Sung Lee, Sang Soo Jee, and Se Yun Kim Materials Research Center, Samsung Advanced Institute of Technology (SAIT), Gyeonggi-do 446-712, Korea
Do Hyang Kima) Center for Non-crystalline Materials, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Korea
Annett Gebert IFW Dresden, Institute for Complex Materials, D-01171 Dresden, Germany
Jurgen Eckertb) IFW Dresden, Institute for Complex Materials, D-01171 Dresden, Germany; and TU Dresden, Institute of Materials Science, D-01062 Dresden, Germany (Received 28 September 2011; accepted 28 December 2011)
The oxidation behavior of Cu50Zr50 and Cu46Zr46Al8 glasses during continuous heating up to 1073 K has been investigated, with special emphasis on the oxidation resistance in the supercooled liquid (SCL) state. For Cu50Zr50, the oxide layer mostly consists of monoclinic ZrO2 (m-ZrO2), while for Cu46Zr46Al8, the oxide layer consists of two different layers: an outer layer consisting of tetragonal ZrO2 (t-ZrO2) + Al2O3 + metallic Cu (oxidation product from the SCL state of the glass matrix) and inner layer comprised of m-ZrO2 + metallic Cu islands (oxidation product from the crystallized matrix). Cu-enriched regions consisting of Cu51Zr14 (in Cu50Zr50) or AlCu2Zr + Cu70Zr15Al15 + Cu51Zr14 (in Cu46Zr46Al8) are present below the oxide layer. The present study shows that the addition of Al (8 at.%) in Cu50Zr50 results in a significant deterioration of the oxidation resistance in the SCL state since the solutionizing of Al in t-ZrO2 leads to a higher oxygen ion vacancy concentration, thus providing a higher activity of oxygen ions.
I. INTRODUCTION
So far there have been great efforts to utilize bulk metallic glasses (BMGs) for structural applications since BMGs provide mechanical properties that cannot be obtained in the counterpart crystalline materials.1,2 However, the low ductility of BMGs is still an obstacle for application as structural materials, although some tensile ductility has been reported recently.3,4 Along with the efforts for the development of structural BMGs, there have been attempts to use BMGs for functional applications. In particular, BMGs can be thermoplastically formed into complex geometries over a length scale ranging from 10 nm to 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.2012.23 1178
J. Mater. Res., Vol. 27, No. 8, Apr 28, 2012
a few centimeters due to the presence of a highly viscous supercooled liquid (SCL) region.5,6 Using such a high thermoplasticity of BMGs, various fabrication methods including micro/nano imprinting,7 blow molding,8 and net-shape forming9 have been successfully applied to produce microsprings,10 microgears,11 nanowires,12 etc.
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