Unraveling the Role of Relaxation and Rejuvenation on the Structure and Deformation Behavior of the Zr-Based Bulk Metallic Glass Vit105

The influence of relaxation and rejuvenation on the deformation behavior of the Zr-based bulk metallic glass Vit105 (Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅) was investigated, where a well-defined thermal history was systematically introduced by thermal treatments. Various annealing states were characterized, covering a broad range that has not been systematically studied so far. Samples with a progressively lower fictive temperature exhibit a lower enthalpic state, coupled with a reduced degree of free volume, which is responsible for the continuous embrittlement observed in three-point beam bending tests. Additionally, it could be shown that complex BMG parts exhibit highly inhomogeneous relaxation states distributed throughout the entire component, allowing the assessment of the mechanical behavior based on the generated database by simple calorimetric measurements and the determination of the fictive temperature. These findings can be transferred to any component made of Vit105, which cannot be easily evaluated in mechanical tests. Diffraction experiments with high energy synchrotron X-ray radiation revealed that the structure is dominated by icosahedral motifs that are forming an icosahedral short-range order. Furthermore, annealing results not only in an ordering on the short- but also the medium-range order. Specifically, the increasing trend in the reduced pair distribution function on the length scale of rigid 3-atom cluster connections were found to be decisive for the reduction in the total strain, as a measure of ductility, indicating a strong correlation with the thermal history. The current findings provide fundamental insights into the role of thermal history in metallic glass forming alloy systems and how it can be used to manipulate the structure and tailor their mechanical properties specifically to the needs of each application.