Negative creep of metallic glasses as an externally-catalyzed dissipative structure within Ginzburg–Landau kinetics

Abstract

Negative creep concerns annealing temperatures of metallic glasses approaching ambient where normal densification is negligible but negative dimensional change is dramatically catalyzed by a LeChatelier-like load perturbation and initially accelerated against the load by temperature and load increase. This obtains on the isotherm up to the load point and time increment where normal creep in the opposite direction begins to counter the anomalous effects. The proposed dissipative structure is based upon strain as a global average order parameter satisfying the postulated time-dependent Ginzburg–Landau (TDGL) equation and applied to Cu 60Zr 40 at 473 K. This serves as the Euler–Lagrange equation corresponding to the experimentally verified Ostwald's Step Rule which subsumes autonomous selection for near reversibility and minimum dissipation or equivalent high free energy configurations en route to equilibrium thus sustaining the G–L postulate. This quench-induced self-organizing phenomenon can be conceived as a continuous stroke potential energy-increasing heat engine driven by the quenched-in thermal energy.