| Abstract Scope |
Cryogenic thermal-cycling is a promising method for rejuvenation. Although seemingly arbitrary, the direction of energy change in MGs following CTC sometimes results in relaxation rather than rejuvenation. By demonstrating enthalpy relaxation in a shear band and enthalpy rejuvenation in the matrix, the current work demonstrates that the initial state matters. Micro-hardness, nano-indentation loading curves, and the shapes of indents all support the bidirectional trends. Notably, after subjecting the specimen to 100 thermal-cycles, the enthalpy and hardness tend to converge into an equilibrium value. It is discovered that CTC can accelerate the structural relaxation of SB at room temperature, a phenomenon that thermal annealing at the upper temperature (353 K) of CTC cannot achieve. Additionally, the experimental results have been elucidated by adapting a free-volume model. The work provides new insights into the functionalities of CTC and illuminates the initial state of the metallic-glass upon reversing the direction of enthalpy change. |