Metallic Glass System Research Articles

Tunable rejuvenation behavior of Zr55Cu35Al10 metallic glass at the atomic scale during recovery annealing and pressure treatment

In this study, molecular dynamics (MD) simulations were employed to investigate atomic structure characteristics of Zr55Cu35Al10 metallic glasses under various annealing temperature and pressure. Following the initial formation of amorphous, the samples annealed at temperatures ranging from 800 K to 1100 K exhibited a transition from an aged state to a rejuvenated state during the subsequent heat treatment stage. In the third stage of heat treatment, increasing the pressure in samples from 0 to 50 GPa significantly enhanced the degree of rejuvenation compared to raising the temperature. Additionally, applying pressure dramatically enhanced the short-range order in the metallic glass system, altered the proportion of icosahedral cluster types, and contributed to a transformation of Voronoi polyhedrons (VPs) from low local five-fold symmetry to high local five-fold symmetry. Notably, the <0,0,12,0> VP, which represents high local five-fold symmetry, reached a peak proportion of 12.5 %, thereby strengthening the amorphous forming ability.

Investigation of Mechanical and Corrosion Properties of New Mg-Zn-Ga Amorphous Alloys for Biomedical Applications.

Magnesium alloys are considered as promising materials for use as biodegradable implants due to their biocompatibility and similarity to human bone properties. However, their high corrosion rate in bodily fluids limits their use. To address this issue, amorphization can be used to inhibit microgalvanic corrosion and increase corrosion resistance. The Mg-Zn-Ga metallic glass system was investigated in this study, which shows potential for improving the corrosion resistance of magnesium alloys for biodegradable implants. According to clinical tests, it has been demonstrated that Ga ions are effective in the regeneration of bone tissue. The microstructure, phase composition, and phase transition temperatures of sixteen Mg-Zn-Ga alloys were analyzed. In addition, a liquidus projection of the Mg-Zn-Ga system was constructed and validated through the thermodynamic calculations based on the CALPHAD-type database. Furthermore, amorphous ribbons were prepared by rapid solidification of the melt for prospective alloys. XRD and DSC analysis indicate that the alloys with the most potential possess an amorphous structure. The ribbons exhibit an ultimate tensile strength of up to 524 MPa and a low corrosion rate of 0.1-0.3 mm/year in Hanks' solution. Therefore, it appears that Mg-Zn-Ga metallic glass alloys could be suitable for biodegradable applications.

Study of Size Effect on Ni60Nb40 Amorphous Particles and Thin Films by Molecular Dynamic Simulations

Ni60Nb40 amorphous particles (APs) and amorphous thin films (ATFs) with various sizes were investigated by molecular dynamic simulations. It is revealed that sample size has effects on both Ni60Nb40 APs and ATFs composed of shell or surface and core components. Ni60Nb40 APs have an average bond length of 2.57 Å with major fivefold-symmetry atomic packing and low bond-orientation orders of Q6 and Q4 in both core and shell components. Ni atoms in Ni60Nb40 APs and ATFs prefer to segregate to the shell and surface regions, respectively. Atomic packing structure differences between various-sized Ni60Nb40 APs and ATFs affect their glass transition temperatures Tg, i.e., Tg decreases as the particle size or the film thickness decreases in Ni60Nb40 APs and ATFs, respectively. Our obtained results for Ni60Nb40 APs and ATFs clearly reveal a size effect on atomic packing and glass transition temperature in low-dimensional metallic glass systems.

Study on the structural origins of glass-forming ability and crystallization behaviors in Ni[sbnd]Nb binary alloys

The limited glass forming ability (GFA) poses a pervasive challenge in different metallic glass (MG) systems. This study systematically investigated the GFA of NiNb binary alloys, particularly those near the eutectic composition, aiming to explore the intrinsic factors contributing to the disparities in GFA among NiNb binary MGs. The relationship between liquid-like atomic structures and resistance to devitrification is thoroughly examined through the application of k-nearest neighbor machine learning methods. The results indicate that the critical diameter of Ni61Nb39, Ni61.5Nb38.5, and Ni62Nb38 MGs reaches upto 2 mm. An amorphous-amorphous transition is discerned within NiNb MGs exhibiting superior GFAs. These alloys exhibit low thermodynamic driving forces for crystallization, resulting in correspondingly elevated fragility coefficients. Furthermore, the presence of icosahedral-like clusters and the probability density of crystal-like clusters are observed to be intricately linked to GFA and the resistance to crystallization in NiNb MGs. The heightened abundance of crystal-like clusters within the liquid-like domain renders the alloy more susceptible to crystallization. Concurrently, icosahedral-like ordered clusters exert a “pinning effect” on the crystal-like regions, effectively inhibiting crystallization. These results collectively shed light on the fundamental nature of glass formation in NiNb binary MGs.

Machine learning-guided exploration and experimental assessment of unreported compositions in the quaternary Ti-Zr-Cu-Pd biocompatible metallic glass system

Due to their outstanding elastic limit, biocompatible Ti-based bulk metallic glasses (BMGs) are candidate materials to decrease the size of medical implants and therefore reduce their invasiveness. However, the practical use of classical Ti-BMGs in medical applications is in part hindered by their high copper content: more effort is thus required to design low-copper Ti-BMGs. In this work, in line with current rise in AI-driven tools, machine learning (ML) approaches, a neural-network ML model is used to explore the glass-forming ability (GFA) of unreported low-copper compositions within the biocompatible Ti-Zr-Cu-Pd system. Two types of models are trained and compared: one based on the alloy composition only, and a second based on various features derived from the alloying elements. Contrary to expectation, the predictive power of both models in evaluating GFA is similar. The compositional space identified by ML as promising is experimentally assessed, finding unfortunately low GFA. These results indicate that the ML approach may be premature for specific composition tuning of amorphous metallic materials. We emphasise that the development of ML tools in GFA prediction requires an improvement of the dataset, in terms of homogeneity, size and GFA descriptors, which must be supported by increased reporting of high-quality experimental GFA measurements, both positive and negative. Statement of significanceBiocompatible Ti-based bulk metallic glasses (BMGs) are candidate materials for use in the next generation of minimally invasive dental implants where improved mechanical properties, such as high strength are required. Despite promising in vitro/vivo evaluations, implementation of alloys for practical applications is partly hindered by the presence of copper as the main alloying element. Recent studies have presented AI-guided and machine learning strategies as appealing approaches to understand and describe the glass forming ability (GFA) of BMG-forming compositions. In this work, we employ and evaluate the capacity of a machine-learning model to explore low-copper compositional spaces in the biocompatible Ti-Zr-Cu-Pd system. Our results highlight the limits of such a computational approach and suggest improvements for future designing routes.

Unveiling glass forming ability patterns in bulk metallic glasses via advanced machine learning approaches

In the present study machine learning (ML) models were used to predict the Glass Forming Ability (GFA) of various bulk metallic glass (BMG) systems. A careful feature selection procedure was employed to identify important parameters that exert influence on glass formation. Linear Regression (LR), Random Forest model (RF), Support Vector Regression (SVR), and K-Nearest Neighbours (KNN) were used to estimate the compositional dependencies through numerous physical, thermodynamic, and topological characteristics on the GFA. Important parameters affecting the glass formation were selected utilising the rigorously curated feature subset RF model yields in Maximum R-squared value amongst all the models showing good predictability of Dmax. Further, three key features, Mismatch entropy (ΔSσ/kB), electronegativity difference (∆χ), and PHSS were identified which shows the highest R2 value (0.749) of Dmax prediction. Hence, this model has pinpointed the ideal glass-forming characteristics. The results obtained through the study will help to provide a better understanding of BMGs and their future development.

Effect of Yttrium Doping on Glass-Forming Ability, Thermal Stability, and Corrosion Resistance of Zr50.7Cu28Ni9Al12.3 Bulk Metallic Glass

Metallic glasses (MGs) possess excellent corrosion resistance due to their amorphous nature. Zr-Cu-Ni-Al is one of the most investigated metallic glass (MG) systems due to its excellent corrosion resistance, relatively low cost, and nontoxic qualities. Yet the application of the Zr-Cu-Ni-Al MGs is still limited by its glass forming ability (GFA). It has been found that the doping of yttrium can purify the Zr-Cu-Ni-Al melt and increase GFA. However, research on the yttrium doping’s corrosion resistance is still lacking. In the present work, (Zr50.7Cu28Ni9Al12.3)100−xYx (x = 0 (Y0), 1 (Y1), 2 (Y2), 3 (Y3)) alloys were prepared, and the effects of the yttrium doping on the thermodynamic parameters, crystallization activation energy, and corrosion resistance were studied. It was found that the doping of yttrium can improve the GFA and the crystallization-activation energy of the Zr50.7Cu28Ni9Al12.3 MG. The largest GFA is obtained when the yttrium-doping content reaches 2 at.%. The parameter γ is found to be most suitable for the GFA evaluation of the (Zr50.7Cu28Ni9Al12.3)100−xYx alloy system. Y2 alloy exhibits the best corrosion resistance among the Y0–Y3 alloys according to the potentiodynamic polarization results. The simultaneous increase of the GFA, thermal stability, and corrosion resistance was achieved in the Zr50.7Cu28Ni9Al12.3 MG by proper yttrium doping.

An ensemble learning based amorphous state predictor for multicomponent alloys

Metallic glasses have received extensive academic attention due to their unique characteristics, such as soft magnetic properties, superconductivity, corrosion resistance, high strength, and hardness. However, its limited glass-forming ability hampers the design of new metallic glass systems. The machine learning models can predict the properties and phase state of an alloy based on the existing experimental data, helping researchers design new alloy systems. Model selection and data balancing are crucial for machine learning models to prevent overfitting and improve model performance. In this paper, we used an ensemble learning model with the artificial neural network and random forest as its base models to obtain better results. Moreover, we proposed a data balancing method to improve the performance of our model for different data distributions by balancing the data distribution between alloy systems and within each alloy system. Finally, compared with other machine learning models, we achieve at least 1.2% and 2.2% loss reduction for known alloy systems with a new composition ratio and new alloy systems, separately. And our data balancing method has a 3.6% performance improvement over the state-of-the-art data balancing method.

Crystallization evolution behavior of amorphous Fe85.7Si7.9B3.6Cr2C0.8 powder produced by a novel atomization process

Fe-Si-B amorphous alloy has the advantages of excellent soft magnetic properties, low magnetic loss, stable DC bias performance and strong corrosion resistance, etc. It is one of the commonly used raw materials for high-end electronic and electrical components. In this study, the thermodynamics and kinetics of the crystallization transition of high magnetic induction amorphous powder Fe85.7Si7.9B3.6Cr2C0.8 produced by a novel atomization process were investigated experimentally under non-isothermal and isothermal conditions based on DSC and XRD. The results show that the high Si contents in the amorphous composition and the eutectic reaction during initial crystallization stage lead to a structural transition between the ordered Fe-Si phases A2(α-Fe(Si)), B2(FeSi) and DO3(Fe3Si), thus resulting in the third exothermic peak of crystallization in the DSC curve of this system. In addition, the first exothermic peak of crystallization corresponding to the eutectic reaction is analyzed in detail in this paper. The crystallization process of the amorphous material is as follows: (a) Amorphous; (b) Amorphous+Fe3B+α-Fe(Si)+Fe3Si+Fe5Si3+FeSi; (c) Amorphous+ Fe3B+Fe2B+α-Fe(Si)+Fe3Si+Fe5Si3+FeSi; (d) Fe2B+α-Fe(Si)+Fe3Si+Fe5Si3+FeSi; (e) Fe2B+α-Fe(Si)+Fe3Si+Fe5Si3. And the undercooled liquid region of the amorphous powder is 52 K, the activation energy of glass transition is 396.73 kJ·mol−1, the activation energy of the first crystallization peak is 292.64 kJ·mol−1, and the fragility value is 27 belongs to strong metallic glass system. It also suggests that the amorphous materials have good thermal stability and glass forming ability (GFA).

Ultralarge-scale anomalous phase separation discovered in a Cr-Fe-Co-Ni-Zr high-entropy metallic glass system

Anomalous phase separation in metallic glasses is a longstanding issue that has been controversial since it was first implied in 1969 due to the influence of microstructure artifacts and the lack of direct large-scale (over nanoscale) evidence. This study confirms an ultralarge scale anomalous glass phase separation phenomenon in a Cr-Fe-Co-Ni-Zr high-entropy metallic glass in which any pair of atomic components has a nonpositive heat of mixing using interferencefree visible-light, atomic force, scanning electron, and double spherical aberration-corrected atomic resolution analytical electron microscopes. The second glassy phase separated from the glassy matrix has an ultralarge size of tens of micrometers, which can be controlled by the cooling rate during sample preparation. A mechanism of before-monotectic-like liquid immiscibility is introduced to interpret the phenomenon, which helps understand the anomalous phase separation in metallic glasses and in other fields, such as liquid-liquid phase separation in cells.

The characterization of cold welding process in CuZr metallic glasses with dissimilar alloying compositions

This work aimed to investigate the cold welding process of dissimilar Cu60Zr40/Cu50Zr50 metallic glass (MG) system through the molecular dynamics (MD) simulation. The mechanical properties and plasticity behavior of the joint zone were also studied with the consideration of stress variations and shear atomic strains under the nanoindentation. The results indicated that the joining evolution was accompanied by the accumulation of shear events in the joint zone. However, one side of the joint was more affected by the atomic rearrangements, which were due to the dissimilar mechanical features of Cu60Zr40 and Cu50Zr50 alloys. The nanoindentation results also showed that the joint zone was considerably softer than the base alloys; however, no sudden shear propagation appeared in this part of the assembly. The strain maps of shear atomic strain under the nanoindentation indicated that the atomic rearrangement and shear band interactions were unsymmetrical in the joint zone so that the Cu50Zr50 side tended to form finer shear bands with more interactive features. Finally, it was concluded that a sound metallurgical bond was attained in the Cu60Zr40/Cu50Zr50 system; however, the good plasticity may come at the expense of strength in the joint zone.

Controlling devitrification in the FeSiB system without alloying additions

Efficient electric machines require soft magnetic materials with superior properties, motivating research on the processing-structure-response correlation in Fe-based metallic glass systems. Here, significant differences in the primary devitrification process and the resulting microstructure of amorphous metallic Fe79Si11B10 alloys synthesized into two different forms by different rapid solidification methods are confirmed. Melt-spun ribbons and water-quenched microwires were investigated with calorimetric, structural, and magnetic probes. It is found that the primary devitrification process of the ribbons occurs at a higher temperature (by 80 K) with a faster exothermic heat release relative to that of the quenched microwires, despite their common chemical composition and fully devitrified structural state. Analysis of the primary devitrification reveals that the ribbons exhibit a ∼70% higher effective activation energy and a ∼110% larger value of Avrami exponent relative to those characterizing the microwires, indicating different devitrification routes taken by these two types of material. In specific, the ribbons crystallize via a continuous nucleation process that partly relies on pre-existing surface nuclei, with an interface-controlled growth mechanism. In contrast, the quenched microwires devitrify solely from pre-existing nuclei, with diffusion-controlled growth. These differences are attributed to unique quenched-in structures that are created by the specific rapid solidification conditions. These results suggest approaches to control the microstructure in FeSiB compositions without the need for non-magnetic alloying additions.

Thermoplastic Forming of a Hydrophilic Surface with a Nanostructure Array on Zr-Cu-Ni-Al-Y Bulk Metallic Glass

The poor thermoplastic formability of reactive Zr-based bulk metallic glass becomes the main limiting factor for replacing the noble-metal-based and Be-rich bulk metallic glasses in nanostructure fabrication. In our work, a (Zr50.7Cu28Ni9Al12.3)98.5Y1.5 bulk metallic glass with good thermoplastic formability has been developed by alloying, where Y addition enlarges the processing window and decreases the viscous resistance of supercooled liquid caused by the high free volume density. The prepared Zr-Cu-Ni-Al-Y bulk metallic glass nanostructure retains the amorphous characteristic and generates the complex oxidization products in the surface layer. The enhanced hydrophilicity of the as-embossed surface follows a Wenzel-impregnating wetting regime, and it can be attributed to the large roughness coefficient induced by the capillary effect. This study provides a low-cost and environmentally friendly bulk metallic glass system to manufacture the nanostructure with a broad prospect in the field of electrocatalysis.

Degradation mechanism of acid orange II in persulfate/Fe-based metallic glass system

Fe-based metallic glasses (MGs) not only are an industrially produced amorphous zero-valent iron (AZVI) with a promising reductive degradability to azo dyes but also can activate persulfate (PS) with sulfate radicals (SO4•-, Eo = 2.5–3.1V) for wastewater remediation. In this study, acid orange II (AOII) was rapidly and efficiently decolored by Fe78Si8B14 MG/PS system with a 99% degradation rate in 8 min. Based on monitoring the degradation rate and the concentration of Fe2+/Fe3+, a two-step degradation mechanism is proposed, that one is deductive degradation by AZVI with products of small organic molecules and Fe2+, and the other is oxidative degradation, where AZVI and Fe2+ activate PS with products of SO4•- and •OH confirmed by the electron spin resonance (ESR) analysis test. The orthogonal experimental design proves that the effects of the experiment operating parameters on the decolorization efficiency from high to low are Fe-based MGs dosage, PS dosage, and reaction temperature. Meanwhile, the high efficiency of the Fe-based MGs/PS system is also illustrated for the mineralization of AOII by an indication of the TOC removal rate as high as 57%. This work gives new insight into Fe-based MGs for activating PS and will accelerate the application of Fe-based MGs as catalysts in the field of wastewater treatment.

The role of titanium content in (Ni75Cr15Si10)100−x Ti x bulk metallic glass systems to elevate mechanical and corrosion properties

ABSTRACT Bulk metallic glass (BMG) samples are amalgamated by high-energy ball milling using the general formula (Ni75Cr15Si10)100−x Ti x (labelled as NCST x , where x = 0,4, 8 and 12 at.%). The crystallinity and phase attribution properties of nickel (Ni), chromium (Cr), silicon (Si) and titanium (Ti) are scrutinized using the XRD analysis. The trend related to glass-forming ability (ΔT) and the GFA parameter (γ) is NCST8 > NCST12 > NCST4 > NCST0, which confirms that NCST8 sample shows superior glass-forming ability. The reduced glass transition temperature (T rg) for all the present BMG systems is greater than 0.5, which offers its good thermal stability and glass-forming ability (GFA). Corrosion studies suggested that a sample, having dynamic nature towards corrosion resistance and potential (E c) (NCST8, (Ni75Cr15Si10)92Ti8), exhibits relatively lower values of both i c (4.7 × 10−4 A/cm2) and i p (0.0079 A/cm2), as recommended in potentio-dynamic findings.

Decoupling between calorimetric and dynamical glass transitions in high-entropy metallic glasses

Glass transition is one of the unresolved critical issues in solid-state physics and materials science, during which a viscous liquid is frozen into a solid or structurally arrested state. On account of the uniform arrested mechanism, the calorimetric glass transition temperature (Tg) always follows the same trend as the dynamical glass transition (or α-relaxation) temperature (Tα) determined by dynamic mechanical analysis (DMA). Here, we explored the correlations between the calorimetric and dynamical glass transitions of three prototypical high-entropy metallic glasses (HEMGs) systems. We found that the HEMGs present a depressed dynamical glass transition phenomenon, i.e., HEMGs with moderate calorimetric Tg represent the highest Tα and the maximum activation energy of α-relaxation. These decoupled glass transitions from thermal and mechanical measurements reveal the effect of high configurational entropy on the structure and dynamics of supercooled liquids and metallic glasses, which are associated with sluggish diffusion and decreased dynamic and spatial heterogeneities from high mixing entropy. The results have important implications in understanding the entropy effect on the structure and properties of metallic glasses for designing new materials with plenteous physical and mechanical performances.

Revealing the structural heterogeneity of metallic glass: Mechanical spectroscopy and nanoindentation experiments

Microstructural heterogeneity is an important issue in understanding the mechanical and physical properties of metallic glasses (MGs). Theoretically, physical aging below the glass transition temperature relax the MGs systems to a lower potential energy state on the potential landscape (PEL) while the cold rolling rejuvenates MGs to a higher potential energy state. In the current work, we systemically turned the structural heterogeneity through dynamic mechanical relaxation and rejuvenation. Correlations among the structural heterogeneity, internal friction, and shear transformation zones (STZs) of the model alloy was connected. Based on the cooperative shear model and statistical analysis, the scale variation of the STZs was revealed. This study demonstrated that the spatial structural heterogeneity can be enhanced by severe plastic deformation which can reduce the energy barrier for STZs activation. And we proposed the barriers decrease and more nucleation sites of STZs from physical aging to rejuvenation, which may be potential mechanism for improving the plasticity in MGs.

Dynamic mechanical relaxation behavior of binary metallic glasses

Secondary β relaxation is a fundamental issue to understand the diffusion, plasticity and glass transition behavior of metallic glasses. Binary metallic glasses provide a simple glassy system to probe the dynamic mechanical processes. In the current research, dynamic mechanical behavior of the typical binary metallic glasses was investigated by dynamic mechanical analysis (DMA). The dynamic mechanical relaxation behavior of Cu50-xTi50+x (x = 0, 7 and 9) and CuxZr100-x (x = 30, 50, 56, 61.8 and 64) binary metallic glass system was studied. It is found that the β relaxation becomes pronounced with the increase of copper, which is analyzed in the framework of the principle of mixing enthalpy. However, the β relaxation of CuZr or CuTi binary metallic glasses is much more modest than that of Y65Co35, Dy65Co35 and Y67Cu33.

The critical model size for simulating the structure-dynamics correlation in bulk metallic glasses

Computational simulation provides an effective way of understanding the disordered structure and structure-property relationships for metallic glass systems. Here, we systematically investigated the finite-size effects of the static structure and dynamical behaviors in a three-dimensional Cu50Zr50 model metallic glass via classical molecular dynamics (MD) simulations. It was found that the local structure is insensitive to the system size while the dynamical properties present evident finite-size effects. The decoupling between local structure and relaxation dynamics in the investigated supercooling emerges when the system contains less than ~2000 atoms. However, the collapse can be observed between the structural relaxation time and the dynamical heterogeneity for different sized systems across the whole range of our investigation. Our results support the intrinsic link between the structural relaxation time and dynamic heterogeneity and reveal the critical simulated system size for representing the structural origins of dynamics in bulk metallic glass with ignorable surface effects.

Evolution of defect concentration in Zr&lt;sub&gt;50–&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Cu&lt;sub&gt;34&lt;/sub&gt;Ag&lt;sub&gt;8&lt;/sub&gt;Al&lt;sub&gt;8&lt;/sub&gt;Pd&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; (&lt;i&gt;x&lt;/i&gt; = 0, 2) amorphous alloys derived using shear modulus and calorimetric data

Amorphous alloys exhibit unique physical and mechanical properties, which are closely connected with their microstructural heterogeneity. The correlation between structural heterogeneity and mechanical properties is one of the important issues of amorphous alloys. Micro-alloying is an effective way to tune the mechanical and physical properties of amorphous alloys. In the present study, Zr&lt;sub&gt;50–&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Cu&lt;sub&gt;34&lt;/sub&gt;Ag&lt;sub&gt;8&lt;/sub&gt;Al&lt;sub&gt;8&lt;/sub&gt;Pd&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; (&lt;i&gt;x&lt;/i&gt; = 0 and 2) amorphous alloys with ability to form excellent glass are chosen as model alloys. The evolutions of heat flow and shear modulus in different states (as-cast, relaxed and crystalline) with temperature of Zr&lt;sub&gt;50–&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Cu&lt;sub&gt;34&lt;/sub&gt;Ag&lt;sub&gt;8&lt;/sub&gt;Al&lt;sub&gt;8&lt;/sub&gt;Pd&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; (&lt;i&gt;x&lt;/i&gt; = 0 and 2) glass system are studied by differential scanning calorimetry (DSC) and electromagnetic-acoustic transformation (EMAT) technique, respectively. The experiment demonstrates that a decrease of the shear modulus is accompanied by the endothermic heat flow and vice versa. The correlation between the heat flow and shear modulus is investigated according to the interstitialcy theory. The calculations of the interstitialcy defect concentration and activation energy spectra suggest that the microstructure remains stable at relatively low temperatures. When temperature increases, the interstitialcy defect structure is activated. Compared with that in the as-cast state, the interstitialcy defect concentration in the relaxed state is reduced by structural relaxation, indicating that temperature-dependent shear modulus softening is inhibited. At temperatures above glass transition temperature, a rapid growth of interstitialcy defect concentration results in the accelerated shear softening, which is accompanied by significant endothermic heat flow. It is noted that the minor addition of palladium reduces the interstitialcy defect concentration in the Zr&lt;sub&gt;50–&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Cu&lt;sub&gt;34&lt;/sub&gt;Ag&lt;sub&gt;8&lt;/sub&gt;Al&lt;sub&gt;8&lt;/sub&gt;Pd&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; (&lt;i&gt;x&lt;/i&gt; = 0 and 2) metallic glass systems. It is suggested that the introduction of Pd reduces the atomic mobility and increases the characteristic relaxation time. In parallel, the change of shear modulus as a function of the aging time (below the glass transition temperature) is studied by using EMAT equipment. The results indicate that the interstitialcy defect concentration decreases in the physical aging process, which is accompanied by an increase of shear modulus. The interstitialcy defect concentration and shear modulus change towards the quasi-equilibrium state with aging time increasing. A reduction of the interstitialcy defect concentration leads to a decrease of the shear modulus change upon microalloying by Pd into Zr&lt;sub&gt;50–&lt;/sub&gt;&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; Cu&lt;sub&gt;34&lt;/sub&gt;Ag&lt;sub&gt;8&lt;/sub&gt;Al&lt;sub&gt;8&lt;/sub&gt;Pd&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt; (&lt;i&gt;x&lt;/i&gt; = 0 and 2) metallic glass system.