# Relation Between the Defect Interactions and the
## 1 Introduction  
Due to their desirable properties, such as high strength and strength-to-weight ratio, as well as good room-temperature wear and corrosion resistance [1; 2; 3; 4; 5; 6], bulk metallic glasses (BMGs) are potential candidates for many industrial applications. Furthermore, BMGs have exhibited excellent combinations of strength and toughness that cannot be achieved by conventional metals [7]. Despite these positive aspects, brittle fracture features are still an issue for most BMGs [8].  
Like crystalline materials, defects play an integral role during the plastic deformation in BMGs. For instance, plastic strain in BMGs is often localized into thin shear bands (-20 nm [9]) that can lead to cracking and subsequent fracture of the alloy [10]. [PERSON] et al. suggested that shear bands can initiate from either the percolation of shear transformation zones (STZs) [11] or casting defects (such as voids and surface notches) that can act as nucleation sites [12]. In addition to shear bands and STZs, soft-zone (SZ) (or liquid-like zone [13]) defects can affect the deformation behavior of BMGs, since they can deflect or defer shear bands and crack propagation [14; 15]. Furthermore, it has been reported that a loss of these defects, due to the thermally-induced structural relaxation, can lead to the embrittlement in BMGs [14].  
One way that shear banding manifests itself in BMGs during plastic deformation is in the form of the serrated flow behavior [16; 17; 18; 19; 20; 21; 22; 23]. This type of behavior is characterized by repeated cycles of a sudden stress drop followed by an elastic reloading [24], and is typically associated with significant changes in the microstructure [25; 26]. The serrated flow in BMGs can be affected by extrinsic parameters, such as the strain rate and temperature, or intrinsic properties, including the elastic modulus [16; 27; 28]. For instance, serrations can be inhibited at low temperatures or high strain rates [29].  
Different types of analytical techniques have been used to analyze the serration behavior in BMGs. These methods include the mean field theory technique [16; 17; 30], statistical analysis methods [31], and complexity analysis techniques [23]. One such complexity technique is known as the refined composite multiscale entropy (RCMSE) method, which estimates the degree of complexity of time-series data [32]. Higher complexity values (sample entropy) are typically characteristic of a less predictable time series, while lower values typically indicate that a time series is more regular [33]. The higher complexity values have also been attributed to a higher degree of \"meaningful structural richness\" [34]. In physiology, the complexity of a time series is indicative of the ability of a biological system to adapt and function in an ever-changing environment [35]. As for the serrated flow in alloys, higher complexity values have been attributed to a greater variety of defect interactions, which is indicative of more complex behavior [23; 36; 37]. For instance, it was reported that in a Zr\({}_{55}\)Cu\({}_{30}\)Ni\({}_{5}\)Al\({}_{10}\) BMG, the increase in the complexity values for the serration behavior corresponded to the creation and interaction of more SZ defects at the higher strain rates [23].  
The purpose of the current investigation is to expand upon the work done in [23]. More specifically, the present work will examine how the thermally-induced structural relaxation affects the dynamical complexity of the serration behavior in a similar Zr-based BMG during compression. Importantly, it is believed that this study will build upon the previous knowledge regarding the influence of structural relaxation on the dynamics of the serrated flow.