β-Relaxation and Crystallization Behaviors in a Pulse-Current-Thermoplastic-Formed La-Based Bulk Metallic Glass

We use the pulse current thermoplastic forming technique based on joule heating to rejuvenate the atomic structure of a La₆₂Al₁₄Ag_2.34Ni_10.83Co_10.83 bulk metallic glass (BMG). The pulse-formed sample exhibits more pronounced β-relaxation than the as-cast one due to the increased free volume. Instead, the sub-T_g annealing clearly weakens the β-relaxation and also makes it more isolated from the α-relaxation, showing contributions from free volume and preferred structure. However, both treatments exhibit little influence on the following α-relaxation and high temperature crystallization kinetics. Our results open an effective way to rejuvenate the structure of BMGs and provide an in-depth understanding of the relationship between structural relaxations and crystallization kinetics of BMGs.