Assessment of rheological and thermodynamic properties of the Pd40Ni40P20 bulk metallic glass around glass transition using an indentation creep technique

Vincent Keryvin (1) , Yann Gueguen (2) , Cedric Bernard (1)

1 LIMATB - Laboratoire d'Ingénierie des Matériaux de Bretagne
2 LARMAUR - LAboratoire de Recherche en Mécanique Appliquée

The thermodynamic and rheological properties of the Pd40Ni40P20 bulk metallic glass are explored by means of an indentation creep technique around the glass transition. We have developed a dedicated instrumented indentation apparatus allowing to assess the mechanical properties at elevated tempera- tures. The analysis of results is made possible by using the viscoelastic solutions of contact mechanics. We also analyse the thermodynamics of creep around glass transition to estimate the activation free energy changes from the activation free enthalpy changes via the shear modulus - temperature data. The shear viscosity values extracted using this technique allow for the derivation of activation energies (free enthalpy 210 kJ/mol, enthalpy 456 kJ/mol, entropy 410 J/mol/K) for the flow process. All these properties were found to closely match with those obtained using conventional techniques for viscosity measure- ments. Compared to the latter, the indentation creep technique requires small volumes and samples are easy to prepare. It is therefore expected that such a technique might be employed for the study of glass transition in metallic glasses.

Domaines: Mécanique des matériaux [physics.class-ph]; Mécanique des matériaux [physics.class-ph]

Vincent Keryvin, Yann Gueguen, Cedric Bernard. Assessment of rheological and thermodynamic properties of the Pd40Ni40P20 bulk metallic glass around glass transition using an indentation creep technique. Journal of Alloys and Compounds, 2011, 509S, pp.S18-S22. ⟨10.1016/j.jallcom.2010.12.114⟩. ⟨hal-00676622⟩