Hidden amorphous phase and reentrant supercooled liquid in Pd-Ni-P metallic glasses

An anomaly in differential scanning calorimetry has been reported in a number of metallic glass materials in which a broad exothermal peak was observed between the glass and crystallization temperatures. The mystery surrounding this calorimetric anomaly is epitomized by half century long studies of Pd-Ni-P metallic glasses, arguably the best glass-forming alloys [1]. Here we show,using a suite of in-situ experimental techniques, including simultaneous small-angle neutron scattering-calorimetry, high-energy X-ray diffraction, and electron microscopy, that Pd-Ni-P alloys have a hidden amorphous phase in the supercooled liquid region. The anomalous exothermal peak is the consequence of a polyamorphous phase transition between two supercooled liquids, involving a change in the packing of atomic clusters over medium-range length scales as large as 18Å. With further temperature increase,the alloy reenters the supercooled liquid phase which forms the room-temperature glass phase upon quenching. The outcome of this study raises a possibility to manipulate the structure and hence the stability of metallic glasses through heat-treatment.

Keywords

Calorimetry, Glass, Crystallization, Alloys, Metallic glasses, X-ray diffraction, Neutron diffraction, Electron microscopy, Amorphous state, Supercooling, Heat treatments

Citation

Lan, S., Ren, Y., Wei, X., Wang, B., Gilbert, E. P., Shibayama, T., Watanabe, S., Ohnuma, M., & Wang, X.-L. (2017). Hidden amorphous phase and reentrant supercooled liquid in Pd-Ni-P metallic glasses. Paper presented at ICNS 2017 (International Conference on Neutron Scattering), Daejeon, South Korea, 9 to 13 July 2017. Retrieved from: http://www.icns2017.org/program.php

URI

http://www.icns2017.org/program.php
https://apo.ansto.gov.au/dspace/handle/10238/11279

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