Monotropic polymorphism in a glass-forming metallic alloy

S. Pogatscher, D. Leutenegger, J. E.K. Schawe, P. Maris, R. Schäublin, P. J. Uggowitzer, J. F. Löffler

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Abstract

This study investigates the crystallization and phase transition behavior of the amorphous metallic alloy Au70Cu5.5Ag7.5Si17. This alloy has been recently shown to exhibit a transition of a metastable to a more stable crystalline state, occurring via metastable melting under strong non-equilibrium conditions. Such behavior had so far not been observed in other metallic alloys. In this investigation fast differential scanning calorimetry (FDSC) is used to explore crystallization and the solid-liquid-solid transition upon linear heating and during isothermal annealing, as a function of the conditions under which the metastable phase is formed. It is shown that the occurrence of the solid-liquid-solid transformation in FDSC depends on the initial conditions; this is explained by a history-dependent nucleation of the stable crystalline phase. The microstructure was investigated by scanning and transmission electron microscopy and x-ray diffraction. Chemical mapping was performed by energy dispersive x-ray spectrometry. The relationship between the microstructure and the phase transitions observed in FSDC is discussed with respect to the possible kinetic paths of the solid-liquid-solid transition, which is a typical phenomenon in monotropic polymorphism.
Original languageEnglish
Article number234002
JournalJournal of Physics Condensed Matter
Volume30
Issue number23
DOIs
Publication statusPublished - 18 May 2018

Keywords

  • amorphous
  • metals
  • phase transformation
  • polymorphism

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