Nanocrystallization of gas atomized Cu 47 Ti 33 Zr 11 Ni 8 Si 1 metallic glass
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Leibniz-Institut für Festko¨rper- und Werkstofforschung Dresden (IFW) Dresden, Institut für Metallische Werkstoffe, D-01171 Dresden, Germany
J. Eckertc)
Fachgebiet (FG) Physikalische Metallkunde, Fachbereich (FB) 11 Material- und Geowissenschaften, Technische Universität Darmstadt, D-64287 Darmstadt, Germany; and Leibniz-Institut für Festko¨rper- und Werkstofforschung Dresden (IFW) Dresden, Institut für Metallische Werkstoffe, D-01171 Dresden, Germany
T. Gemming
Leibniz-Institut für Festko¨rper- und Werkstofforschung Dresden (IFW) Dresden, Institut für Festkörperanalytik und Strukturforschung, D-01171 Dresden, Germany
C. Mickel and L. Schultz
Leibniz-Institut für Festko¨rper- und Werkstofforschung Dresden (IFW) Dresden, Institut für Metallische Werkstoffe, D-01171 Dresden, Germany
D.J. Sordelet
Material and Engineering Physics Program, Ames Laboratory (USDOE), Iowa State University, Ames, Iowa 50014; and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50014 (Received 16 June 2005; accepted 18 August 2005)
Cu47Ti33Zr11Ni8Si1 metallic glass powder was prepared by gas atomization. Decomposition in the amorphous alloy and primary crystallization has been studied by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electron microscopy (TEM). The glassy powder exhibits a broad DSC exotherm prior to bulk crystallization. Controlled annealing experiments reveal that this exotherm corresponds to a combination of structural relaxation and nanocrystallization. A uniform featureless amorphous contrast is observed in the TEM prior to the detection of nanocrystals of 4–6 nm in size. High-resolution TEM studies indicate that this nanocrystalline phase has a close crystallographic relationship with the $–CuTi phase having a tetragonal structure. The product of the main crystallization event is also nanocrystalline, hexagonal Cu51Zr14, having dimensions of 20 nm. However, there is no evidence for possible amorphous phase separation prior to the nanocrystallization events. I. INTRODUCTION
Metallic glasses can be formed upon cooling of liquid by avoiding nucleation and growth of crystalline phases.1,2 Studying the crystallization process of metallic glasses is important for understanding the glass formation in metallic systems and their stability and helps in the design of
a)
Address all correspondence to this author. e-mail: [email protected] b) Present address: FG Physikalische Metallkunde, FB 11 Materialund Geowissenschaften, Technische Universität Darmstadt, Petersenstraße 23, D-64287 Darmstadt, Germany. c) 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/publications/jmr/policy.html. DOI: 10.1557/JMR.2006.0072 J. Mater. Res., Vol. 21, No. 3, Mar 2006
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metallic glass systems.3,4 When metallic glasses crystallize at temperatures near t
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