• Pogatscher, Stefan
• Schäublin, R.
• Leutenegger, D.
• Maris, P.
• Schawe, J. E. K.
• Löffler, Jörg F.
• Uggowitzer, Peter J.

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.

Topics

• impedance spectroscopy
• microstructure
• amorphous
• x-ray diffraction
• crystalline phase
• glass
• glass
• phase transition
• transmission electron microscopy
• differential scanning calorimetry
• forming
• annealing
• crystallization
• spectrometry
• metastable phase