Heterogeneity dependent cryogenic thermal cycling behavior of metallic glasses: A potential energy landscape perspective

Even though cryogenic thermal cycling (CTC) was well documented to be an effective and non-destructive way to plasticity and toughness of metallic glasses (MGs), non-monotonic (rejuvenation to relaxation and vice versa) and even monotonic relaxation processes were reported frequently and the underlying mechanism is remain unsolved until now. By systematically alter the heterogeneity of a La-based MG via annealing treatment, in the present study, the effect of heterogeneity on CTC induced behavior of the MG were evaluated and analyzed. A typical non-monotonic process, i.e., rejuvenation first and then relaxation, was captured and the cycling number and heterogeneity dependent relaxation enthalpy and hardness were evaluated and extended discussion. The rejuvenation-relaxation process along with other non-monotonic and monotonic processes gathered from previous studies could be interpreted by the perspective of energy potential landscape. Specifically, the location where the corresponding energy state correlated to the specific heterogeneity of the MG located in the energy landscape determined whether rejuvenation or relaxation occurs upon CTC treatment.