# Relation Between the Defect Interactions and the
## 2 Materials and Methods  
### Mechanical and Microstructural Characterization  
The Zr\({}_{52.5}\)Cu\({}_{17.9}\)Ni\({}_{14.6}\)Al\({}_{10}\)Ti\({}_{5}\) BMG (also known as BAM-11) in atomic percent was fabricated at the University of Tennessee by arc melting in a Ti-gettered argon atmosphere, using a mixture of base pure metals (weight purity \(\geq\)99.9%). The ingots were remelted at least four times, to ensure the compositional homogeneity. Subsequently, the cylindrical rod samples with a diameter of 3 mm and a length of about 60 mm were prepared by suction casting into a water-cooled copper mold. The alloys were then remelted and drop cast in a Zr-gettered helium atmosphere. Subsequently, the rod was remelted and drop cast into a water-cooled 7-mm-diameter cylindrical Cu mold contained within a Zr-gettered helium atmosphere. After fabrication, 6-mm-long samples were cut from the rod using a diamond saw. To examine the effects of thermal annealing on the mechanical behavior, samples were encased in a vacuum-evacuated quartz tube and subsequently annealed. The annealing condition was 300 \({}^{\circ}\)C (ramp rate of 5 \({}^{\circ}\)C/min) for one week. The above temperature was chosen since it is well below the reported glass transition temperature (393 \({}^{\circ}\)C [38]) of the alloy.  
Bulk X-ray diffraction (XRD) was performed on the as-cast and thermally-annealed specimens at the Joint Institute for Advanced Materials (JIAM) Diffraction Facility at the University of Tennessee. The XRD was performed using a PANalytical Empyrean diffractometer equipped with a Xe proportional detector that employed the powder Bragg-Brentano geometry. The X-ray consisted of a Cu beam with a K-alpha wavelength of 1.54 A, in addition to an accelerating voltage and current of 45 kV and 40 mA. The diffraction angle, 20, ranged between 20-80\({}^{\circ}\), in which data was recorded every 0.013 degrees. Before running the experiment, samples were placed on a zero-background holder to shield out any diffraction patterns that were not associated with the sample.  
Room-temperature nanoindentation hardness and Young's modulus measurements were performed using a KLA-Tencor G200 Nano-indenter with a Berkovich 3-sided pyramidal diamond tip in a continuous stiffness-measurement mode with a constant loading rate of 400 \(\upmu\)N s\({}^{-1}\). Before indenting, samples were polished to a mirror finish using colloidal silica (50 nm). The hardness and Young's modulus were measured as a function of depth from the point of contact of the nanoindenter tip with the surface to a depth of \(\sim\)2000 nm. For each test, \(\sim\)20 indents were performed, in which the indent was placed at least 50 \(\upmu\)m from other indents, large scratches, and sample edges to avoid the effect of strain fields [39]. Hardness was calculated using the Oliver and Pharr method [40; 41]. Due to the large data scatter that is associated with surface roughness, hardness and modulus values for depths below \(\sim\)200 nm were omitted.  
For the compression tests, the as-cast and thermally-annealed (300 \({}^{\circ}\)C, 1 week) Zr52.5 Cu17.9 Ni14.6 Al10 Ti5 BMG specimens underwent room-temperature compression tests at strain rates of \(2\times 10^{-5}\) s\({}^{-1}\) and \(2\times 10^{-4}\) s\({}^{-1}\) using a computer-controlled MTS 810 materials testing machine. The samples had a length of 6 mm and diameter of 3 mm (unconstrained condition). Before testing, the two compression faces of each sample were carefully polished such that they were parallel to one other, ensuring adequate contact with the platens during compression. A data-acquisition rate of 100 Hz was used to record the stress vs. time measurements.