Next Article in Journal
Understanding Shock Response of Body-Centered Cubic Molybdenum from a Specific Embedded Atom Potential
Previous Article in Journal
Evaluation of the Suitability of High-Temperature Post-Processing Annealing for Property Enhancement in LPBF 316L Steel: A Comprehensive Mechanical and Corrosion Assessment
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Enhancing Fracture Toughness, Strength and Ductility of Zr58.75Cu21.15Fe4.7Al9.4Nb6 Bulk Metallic Glass via Ultrasound Excitation Technique

1
State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
2
Key Laboratory of Surface Engineering of Equipment for Hydraulic Engineering of Zhejiang Province, Standard and Quality Control Research Institute, Ministry of Water Resources, Hangzhou 310024, China
3
Water Machinery and Remanufacturing Technology Engineering Laboratory of Zhejiang Province, Hangzhou River Mechanical and Electrical Equipment Engineering Co., Ltd., Hangzhou 310024, China
4
School of Materials Science and Engineering, Xinjiang University, Urumqi 830017, China
*
Authors to whom correspondence should be addressed.
Metals 2025, 15(6), 683; https://doi.org/10.3390/met15060683
Submission received: 16 May 2025 / Revised: 13 June 2025 / Accepted: 17 June 2025 / Published: 19 June 2025

Abstract

The inherent brittleness and limited toughness of bulk metallic glasses (BMGs) remain critical challenges for their application as structural engineering materials. In this study, ultrasonic excitation was applied to Zr58.75Cu21.15Fe4.7Al9.4Nb6 BMG with the aim of enhancing its mechanical performance. The results reveal that ultrasonic treatment significantly increases the fracture toughness by approximately 28% and induces a pronounced plastic deformation plateau following yielding. This improvement in both strength and ductility is attributed to the formation of nanoscale crystalline phases and ultrasound-induced phase separation within the amorphous matrix, which collectively promote shear band multiplication and inhibit crack propagation.

1. Introduction

Bulk metallic glasses (BMGs) exhibit a range of remarkable properties that make them attractive for various applications, including a high elastic strain limit, high strength and hardness, and excellent corrosion resistance [1,2,3,4,5]. However, their lack of an inherent microstructure often results in severe strain localization within narrow shear bands. Consequently, BMGs typically present limited macroscopic plasticity and low fracture toughness, sometimes fracturing without any measurable plastic strain at room temperature. These characteristics significantly restrict their use as structural materials.
For brittle rare-earth and ferrous-based metal glasses [6,7], fracture toughness values are typically just above 1 MPa m0.5. The notch toughness of the first commercial bulk metallic glass, Vitreloy 1 (Zr41.2Ti13.8Cu12.5Ni10Be22.5) [8], ranges from 55 to 59 MPa m0.5 [9], which is significantly lower than that of ductile metals such as low-carbon steels (>200 MPa m0.5) [10]. Enhancing the ductility of BMGs requires the activation of multiple shear bands with reduced shear band spacing, thereby mitigating the rapid propagation of individual shear bands and improving overall toughness.
Recent studies have identified structural heterogeneities in BMGs, characterized by the presence of soft and hard regions [11,12,13]. The soft regions exhibit a viscoelastic flow feature, facilitating deformation and shear band nucleation. Based on those deformation mechanisms, various novel approaches have been explored depending on the mode of external force [14,15,16,17]. For example, thermal cycling [14,15] can rejuvenate the structure of BMGs to a heterogeneous state, resulting in the improvement of the plasticity of BMGs. Ion radiation [16] can induce the appearance of vacancy-like defects in the BMG structure, which can also enhance its plasticity. Laser shock peening [17] can introduce compressive residual stresses and the formation of localized shear bands, enhancing the ductility of BMGs. However, these methods typically compromise material strength while improving ductility.
Ultrasound excitation represents another potential method for modifying the atomic structure of BMGs through forced atomic and molecular vibrations. Recent studies have demonstrated that ultrasonic vibration near the glass transition temperature Tg accelerates the crystallization in Pd40Ni40P20 BMG [18,19], while ultrasonic nanocrystal surface modification has been shown to induce microstructural inhomogeneity in Vit1b BMG [20]. However, whether ultrasonic excitation can enhance the fracture toughness of BMGs remains an open question.
In this study, we applied intensive 20 kHz ultrasound excitation to a Zr58.75Cu21.15Fe4.7Al9.4Nb6 BMG and observed a significant improvement in its structure toughness. A transmission electron microscope (TEM) was employed to analyze the structural changes before and after ultrasonic treatment, as well as the shear band structure after fracture. The underlying mechanisms through which ultrasound excitation enhances the fracture toughness of BMGs are discussed. These findings provide valuable insights for the development of more ductile BMGs.

2. Experimental

Alloy ingots with a composition of Zr58.75Cu21.15Fe4.7Al9.4Nb6 were produced through the process of arc melting. Elemental metals of exceptional purity (≥99.5% by weight) were handled within a titanium-gettered argon environment. To guarantee uniformity in the composition of the alloy, each ingot underwent a minimum of four remelting processes. Subsequently, the alloy was suction-cast into a copper mold, yielding plates measuring 3 mm by 6.5 mm by 40 mm.
A tailor-made ultrasonic apparatus, featuring a KNbO3 piezoelectric transducer with a resonant frequency of 20 kHz and a cylindrical emitter measuring 20 mm in diameter and 500 mm in length, was utilized to administer ultrasonic stimulation. The as-cast plate was affixed to a supporting platform using adhesive, positioned directly beneath the emitter. The emitter was lowered via a precision displacement controller until its end face made tangential contact with the plate surface. Longitudinal ultrasound waves, possessing an amplitude near 15 micrometers, were administered for periods of 15 min and 30 min.
Samples intended for the evaluation of fracture resistance were precisely fabricated from both the processed and unprocessed panels. These specimens were characterized by dimensions with a thickness of 3 mm, a width of 6 mm, and a distance between supports of 24 mm. The six surfaces of the sample were successively ground with 400, 800, 1200 and 2000 grit sandpapers, and then polished to a mirror finish with diamond grinding paste of 5 μm particle size. They were meticulously smoothed and buffed to achieve a reflective surface before assessment. A continuous notch was created by means of wire-electrode discharge machining, featuring a root radius close to 300 micrometers and a notch approximately 0.4 times the specimen width. A cycle of pre-cracking to induce fatigue was applied using a WDW-10E (Shanghai, China) universal testing apparatus under ambient conditions. The cumulative length of the crack, combining both the notch and the pre-existing fatigue-induced crack, was maintained between 0.45 and 0.55 times the width (W).
The fracture toughness of the material was assessed through the application of three-point bend tests utilizing the WDW-10E apparatus at ambient temperature. The thin-foil specimens intended for the transmission electron microscope (TEM, Tecnai G2 F20, FEI, Hillsboro, OR, USA) were crafted from samples that had undergone a mechanical polish (with thicknesses of 30–40 micrometers) by employing the method of twin-jet electropolishing (Buehler, Lake Bluff, IL, USA); the volume ratio of the double spray electrolytic polishing solution is 5:85:5, consisting of perchloric acid, methanol and deionized water.
The amorphous nature of the samples was verified by X-ray diffraction (XRD, Bruker D8 ADVANCE diffractometer in Billerica, MA, USA) with Cu Kα radiation. Crystallization kinetics were investigated via differential scanning calorimetry (DSC, Netzsch STA 449C, Sürburg, Germany) under high-purity argon atmosphere, employing a constant heating rate of 5 K/min. Microstructural observations of lateral and fracture surfaces were examined using field-emission scanning electron microscopy (SEM, LEO1430VP, Zeiss, Jena, Germany). For atomic-scale structural analysis, high-resolution transmission electron microscopy (HRTEM, Tecnai G2 F20, FEI, Hillsboro, OR, USA), coupled with an energy-dispersive X-ray spectroscopy (EDX) system for concurrent elemental mapping.

3. Results

3.1. Characteristic Structure of Both As-Cast and Ultrasonically Processed Specimens

Figure 1 presents X-ray diffraction patterns for the Zr58.75Cu21.15Fe4.7Al9.4Nb6 plate samples in the as-cast state (U-0) and after ultrasonic treatment for 15 min (U-15) and 30 min (U-30). Every specimen displays a wide diffuse peak indicative of a non-crystalline framework, lacking any distinct peaks associated with crystalline structures. This substantiates the fact that the amorphous state is preserved in both the non-treated and the ultrasonically processed specimens.

3.2. Thermal Characterization

The differential scanning calorimetry (DSC) traces for the U-0, U-15, and U-30 samples, as depicted in Figure 2, reveal that at a rise of 5 kelvins per minute, each sample presents a clear glass transition, progresses through a sharp superliquid region, and undergoes crystallization. It is important to highlight that the starting point of the glass transition temperature, Tg, is 649 K, and the initial crystallization, Tx, is 706 K, which are almost identical across the samples. The width of the undercooled liquid-phase region, Tx-Tg, is 57 K, which is not significantly different from the width of the cold liquid-phase region in most Zr-based BMGs [21], indicating that it has a high glass-forming ability. This suggests that the ultrasonic exposure has a negligible impact on the thermal stability of the alloy.

3.3. Fracture Toughness Properties

The assessment of fracture toughness was performed by conducting three-point bending tests on fatigue pre-cracked samples. Figure 3 presents the related load-versus-displacement graphs. When examining the untreated cast specimen (U-0) relative to those subjected to ultrasonic treatment (U-15 and U-30), there is a noticeable enhancement in maximum loads, rising from 1.515 kN for the U-0 sample to 1.900 kN and 1.924 kN (U-15 and U-30, respectively). Additionally, the appearance of a distinct plastic plateau following yielding in the U-15 and U-30 samples suggests enhanced ductility due to ultrasonic excitation.
Computation of the peak fracture robustness with the open-type fracture toughness, KIc, was performed in adherence with the ASTM E399 standard [22], employing Equations (1) and (2).
K = P S B W 1.5 f ( a W )
f ( a W ) = 3 a W 1.99 ( a W ) ( 1 a W ) [ 2.15 3.93 a W + 2.7 ( a W ) 2 ] 2 ( 1 + 2 a W ) ( 1 a W ) 1.5
Here, P represents the maximum stress applied to the specimens, S refers to the distance between supports, and B is the measurement of thickness. The width of the sample and the length of the pre-crack are, respectively, denoted by W and a. The calculated Kmax values are 69 MPa m0.5 for U-0, 87 MPa m0.5 for U-15 and 88 MPa m0.5 for U-30, indicating an approximate 28% improvement in fracture toughness as a result of ultrasonic treatment.

3.4. Shear Bands and Fracture Morphologies

Figure 4 illustrates the side surfaces of the U-0 (Figure 4a) and U-30 (Figure 4b) specimens after bending. Shear bands are clearly observed around the notch area in all samples. However, in the U-30 sample, the shear bands (highlighted by green boxes) are more densely distributed and exhibit increased branching and interaction. Additionally, the size of the shear band area, marked by green circles, is significantly greater in U-30, with an approximate diameter of 0.7 mm, when contrasted with the roughly 0.3 mm diameter of U-0.
The fractographic analysis reveals that ultrasonically modified specimens exhibit characteristic meandering crack paths (as demarcated by yellow arrows in the representative SEM micrograph, Figure 4b), indicative of crack deflection mechanics through successive bifurcation events. This tortuous propagation morphology demonstrates the following: (1) enhanced extrinsic toughening via crack path optimization; (2) progressive energy dissipation through secondary crack branching; (3) residual stress-induced crack closure effects. These synergetic toughening mechanisms collectively elevate the fracture work compared to as-cast specimens, fundamentally altering the failure mode from brittle cleavage to ductile tearing.

3.5. Evolution of Microstructure Before and After Ultrasonic Treatment

Figure 5a and Figure 6a show low- and high-magnification TEM images of U-0 before the three-point bending test. It shows no contrast in the image, and the corresponding SAED pattern shown in the inset of Figure 5a indicates that there is only a diffusive halo, confirming the amorphous nature of this alloy. The high-resolution TEM (HRTEM) image also indicates that there is no nanocrystal (see the inset of Figure 6a); the image also confirms an amorphous structure for U-0. However, for U-30, as shown in Figure 5b, there are ~20 nm dark phases (highlighted by green circles) on the glassy matrix; as the fraction of them is less than 10%, the SAED pattern image only shows a diffuse halo and a small number of diffraction spots. However, the HRTEM image of U-30 (Figure 6b) shows that the dark phases are nanocrystals, which indicates that the alloy is partially crystallized via ultrasonic treatment, showing lattice fringes with equal spacing (highlighted by blue circles). Figure 7a shows the scanning TEM (STEM) image of U-30. From the elemental mapping of Zr, Cu, Fe, Al and Nb, as shown in Figure 7b–f, it can be found that the main element of the precipitates is Cu-rich, which indicates that the composition distribution is not uniform.

4. Discussion

As mentioned above, the ultrasonic-treated samples exhibited enhanced yield stress and a distinct plastic plateau following yielding, indicating improved plasticity compared to the as-cast sample. A thorough examination of the microscopic characteristics in both the U-0 and U-30 specimens, before and after deformation, was performed to clarify the underlying mechanisms that account for the noted enhancements in strength and ductility.
Figure 5a displays a transmission electron microscopy (TEM) image at low magnification for the U-0 sample before it was deformed. The homogenous appearance in this image, coupled with the appearance of a blurred ring in the selected area electron diffraction (SAED) pattern, where the diameter of the SAED pattern was about 1 μm, corroborates the sample’s completely amorphous constitution. Moreover, as shown in Figure 6a, an examination with high-resolution transmission electron microscopy (HRTEM) substantiates this finding, as it shows the absence of any nanocrystalline structures.
Conversely, the U-30 specimen exhibits considerable alterations in its structure following exposure to ultrasonic processing. As shown in Figure 5b, small dark contrast features (~20 nm) appear within the amorphous matrix. The SAED pattern displays a diffuse halo and a small number of diffraction spots because the features occupy a minor volume fraction (less than 10%); HRTEM (Figure 6b) confirms that they are nanocrystals, as evidenced by the presence of lattice fringes in the inset. These findings suggest partial crystallization induced by ultrasonic excitation.
It is probable that the appearance of these nanocrystals can be ascribed to the inherent metastability of bulk metallic glasses (BMGs), which are prone to crystallizing when subjected to external factors like thermal exposure [23,24,25] or mechanical stress [5,13]. Ultrasound generates strong forced vibration, enhancing atomic mobility and diffusivity through mechanisms such as acoustic cavitation and streaming [26]. Recently, similar ultrasonic-induced crystallization phenomena have been reported in Pd-based BMGs by Ichitsubo et al. [18,19].
Therefore, it is reasonable to deduce that ultrasonic excitation promotes atomic rearrangement, allowing atoms to occupy lower-energy configurations. This enhanced mobility facilitates structural relaxation and eventual crystallization. Under such conditions, atomic jumps deviate from conventional diffusion behavior. The cumulative effect of such anomalous displacements perturbs the thermodynamic energy landscape, ultimately driving the nucleation of crystalline phases through localized energy minimization. According to Fan et al. [24], strength improvements occur when the crystalline volume fraction remains below ~30%, as also supported by other studies [23,25]. This study reveals that nanocrystals, which are more minute than typical shear bands (approximately 10 nanometers), are dispersed haphazardly throughout the material, obstructing the extension of shear bands and preserving the amorphous structure. Such an enhancement at the microscopic level contributes to a rise in both the resistance to breaking and yield strength.
Moreover, ultrasonic excitation likely promotes structural relaxation, driving atoms into more stable positions. This process increases packing density in formerly loose-packed regions, reducing local structural weaknesses and contributing to overall strength and ductility. When the size of the nano-particles is much smaller than that of the shear band and the nano-particles are separated by a glassy matrix, the deformation of the shear band is dominated by the glassy matrix, and the nanocrystals may inhibit the deformation of the shear bands [23]. Thus, it can be inferred that a small amount of precipitated nanocrystals leads to an increase in fracture stress and yield stress. The causes of the increase in fracture stress and yield stress may be as follows: Firstly, the high-strength nanocrystals serve as robust obstacles like nails that effectively restrict the propagation of shear bands and arrest crack advancement through microstructural pinning effects. In this work, 2–5 nm nanocrystals precipitated on the glassy matrix during the ultrasound excitation for U-30 (Figure 6b), and their size was much smaller than that of the shear band. The volume fraction of the crystalline part of U-30 was less than 10%, and the amorphous matrix was mainly retained. In this stress-concentrated configuration, these localized high-stress nanocrystals distributed along shear bands acted as effective obstacles, which not only obstructed further propagation of the primary shear bands but also delayed crack initiation and growth. Secondly, owing to the pronounced stress gradient at crystalline–amorphous interfaces, primary shear bands preferentially nucleate through stress-activated free volume coalescence, subsequently undergoing directional propagation governed by interfacial shear stress anisotropy. These secondary shear bands form hierarchical branching networks with wing-like primary counterparts, creating a three-dimensional stress redistribution architecture that enables (1) strain accommodation through coordinated shear band intersection and bifurcation; (2) energy dissipation via interface-mediated dislocation–STZ (shear transformation zone) interactions; and (3) crack blunting by shear band network rearrangement. This multiscale deformation synergy effectively delays strain localization while maintaining structural integrity under loading. Consequently, the partial crystallization, in tandem, improves both strength and the capacity of plastic deformation [27,28,29].
To deepen the insight into the impact of ultrasound, the elemental composition distribution of specimen U-30 was examined. Figure 7a shows a scanning TEM (STEM) image with visible spherical precipitates, consistent with the dark contrast features observed in Figure 5b. Elemental mapping (Figure 7b–f) reveals that these precipitates are Cu-rich, indicative of local chemical inhomogeneity. The elemental line scanning image of Figure 7g shows the distribution of Zr, Cu, Al, Fe and Nb elements along the blue arrow in Figure 7a, which indicates that the concentration of the Cu element reaches a peak in the Cu-rich area and then becomes relatively stable in the Cu-poor area.
Viewed through the lens of thermodynamics, the emergence of distinct phases can be attributed to the endothermic nature of mixing for Cu-Fe (13 kJ/mol) and Cu-Nb (3 kJ/mol) pairs [30], which promotes segregation. Conversely, the Fe-Nb pair, displaying an exothermic mixing response with an enthalpy of −16 kJ/mol, favors the creation of regions rich in Fe and Nb. Although Fe and Nb are present in low concentrations and not clearly resolved in EDS, Cu is abundant and has a diffusion coefficient significantly higher than that of Zr [30], making it more prone to mobilization during deformation. The suppression of Cu mobility by larger Zr and Al atoms likely results in the formation of Cu-rich zones [31]. Interestingly, phase separation is absent in the untreated U-0 sample, suggesting that ultrasonic excitation plays a critical role in triggering this phenomenon. This aligns with prior findings regarding phase separation in amorphous alloys triggered by stress or heat, as documented in earlier works [32]. Ultrasonic stress and prolonged localized heating may synergistically promote the development of heterogeneous microstructures in U-30.
These Cu-rich zones act as soft zones [33], reaching critical shear stress earlier than the surrounding harder glass matrix. According to the concept of shear transformation zones (STZs), soft regions initiate deformation, while adjacent hard regions constrain it, resulting in STZ branching and the multiplication of shear bands. This behavior contributes to increased crack resistance and improved plasticity, as observed in the U-30 sample. Thus, deformation-induced phase separation provides an additional explanation for the enhanced mechanical performance (especially fracture toughness) and plastic platform observed in U-30.
In summary, ultrasonic treatment can induce structural changes in bulk metallic glass. The internal microstructure variation mechanism of bulk metallic glasses under ultrasonic treatment is shown in Figure 8. The amorphous structure is in an unstable form. Ultrasonic treatment induces multiscale structural modifications in bulk metallic glasses through thermomechanical coupling effects, and the amorphous structure undergoes phase separation or crystallization. In the first place, under the action of ultrasonic treatment, the atoms in the bulk metallic glass are rearranged. High-frequency ultrasonic vibrations generate localized stress concentrations, activating cooperative shear transformations that facilitate atomic reconfiguration through free volume redistribution. This process triggers structural relaxation with a reduced activation energy barrier under the continuous action of ultrasonic treatment, and atoms in certain regions of bulk metallic glasses may crystallize, forming nanocrystals. The ultrasonic-induced stress gradient drives preferential nucleation of nanocrystalline phases at stress-concentrated regions. These nanocrystals form semi-coherent interfaces with the amorphous matrix. Simultaneously, phase separation occurs in some regions of the bulk metallic glass under the continuous action of ultrasonic treatment. There are two different kinds of phase separation. One form of phase separation is amorphous–amorphous phase separation. The compositional fluctuations promote the formation of copper-rich amorphous regions in zirconium-based amorphous materials. Another form of phase separation is crystal–amorphous phase separation. Localized crystallization occurs in phase-separated regions through stress-assisted diffusion. This improvement in both strength and ductility is attributed to the formation of nanoscale crystalline phases and ultrasound-induced phase separation within the amorphous matrix, which collectively promote shear band multiplication and inhibit crack propagation.

5. Conclusions

In this research, how ultrasonic excitation influences the mechanical characteristics and the internal microstructure of Zr58.75Cu21.15Fe4.7Al9.4Nb6 alloy in its bulk metallic glass (BMG) form was systematically investigated. The principal results have been methodically examined and are concisely presented below:
(1)
Enhanced Fracture Toughness: The fracture toughness of Zr58.75Cu21.15Fe4.7Al9.4Nb6 BMG was significantly improved by approximately 28% through ultrasound excitation, as demonstrated by three-point bending tests.
(2)
Ultrasound-Induced Nanocrystallization: Ultrasound treatment led to partial nanocrystallization of the BMG, which contributes to increased strength and toughness by inhibiting shear band propagation and promoting structural relaxation.
(3)
Ultrasound-Induced Phase Separation: The ultrasound excitation also induced chemical inhomogeneity in the form of Cu-rich phase-separated zones. These soft zones facilitate the initiation of shear transformation zones (STZs), while the surrounding hard matrix impedes their propagation, resulting in the multiplication of shear bands and enhanced resistance to crack growth.
Overall, ultrasonic treatment provides a promising strategy for tailoring the mechanical performance of bulk metallic glasses by promoting beneficial microstructural modifications such as partial nanocrystallization and phase separation.

Author Contributions

Conceptualization, X.H.; methodology, X.C., T.W., Y.L. and R.B.; formal analysis, X.C., Z.Z., T.W., Y.L., R.B. and M.W.; investigation, Z.Z. and M.W.; data curation, X.C.; writing—original draft, X.C. and T.W.; writing—review and editing, T.W. and X.H.; visualization, Z.Z.; supervision, X.H.; funding acquisition, X.H. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (No. U23A20621, U22A20105, No. 52461031) and the Natural Science Foundation of Xinjiang Uygur Autonomous Region of China (No. 2024D01C13).

Data Availability Statement

The original contributions presented in this study are included in the rticle. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

Authors Xiaoming Chen and Mingming Wang were employed by the company Water Machinery and Remanufacturing Technology Engineering Laboratory of Zhejiang Province, Hangzhou River Mechanical and Electrical Equipment Engineering Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Wang, W. The Elastic Properties, Elastic Models and Elastic Perspectives of Metallic Glasses. Prog. Mater. Sci. 2012, 57, 487–656. [Google Scholar] [CrossRef]
  2. Liu, Y.; Wang, G.; Wang, R.; Zhao, D.; Pan, M.; Wang, W. Super plastic bulk metallic glasses at room temperature. Science 2007, 315, 1385–1388. [Google Scholar] [CrossRef]
  3. Lu, Z.; Jiao, W.; Wang, W.; Bai, H. Flow Unit Perspective on Room Temperature Homogeneous Plastic Deformation in Metallic Glasses. Phys. Rev. Lett. 2014, 113, 045501. [Google Scholar] [CrossRef]
  4. Gao, M.; Dong, J.; Huan, Y.; Wang, Y.; Wang, W. Macroscopic tensile plasticity by scalarizating stress distribution in bulk metallic glass. Sci. Rep. 2016, 6, 21929. [Google Scholar] [CrossRef]
  5. Wang, T.; Si, J.; Wu, Y.; Lv, K.; Liu, Y. Two-step work-hardening and its gigantic toughening effect in Zr-based bulk metallic glasses. Scr. Mater. 2018, 150, 106–109. [Google Scholar] [CrossRef]
  6. Xi, X.; Zhao, D.; Pan, M.; Wang, W.; Wu, Y.; Lewandowski, J.J. Fracture of Brittle Metallic Glasses: Brittleness or Plasticity. Phys. Rev. Lett. 2005, 94, 125510. [Google Scholar] [CrossRef]
  7. Hess, P.A.; Poon, S.J.; Shiflet, G.J.; Reinhold, H.D. Indentation fracture toughness of amorphous steel. J. Mater. Res. 2005, 20, 783–786. [Google Scholar] [CrossRef]
  8. Peker, A.; Johnson, W.J. A highly processable metallic glass: Zr41.2Ti13.8Cu12.5Ni10.0Be22.5. Appl. Phys. Lett. 1993, 63, 2342–2344. [Google Scholar] [CrossRef]
  9. Conner, R.D.; Rosakis, A.J.; Johnson, W.L.; Owen, D.M. Fracture toughness determination for a beryllium-bearing bulk metallic glass. Nat. Mater. 1997, 37, 1373–1378. [Google Scholar] [CrossRef]
  10. Demetriou, M.D.; Launey, M.E.; Garrett, G.; Schramm, J.P.; Hofmann, D.C.; Johnson, W.L.; Ritchie, R.O. A damage-tolerant glass. Nat. Mater. 2011, 10, 123–128. [Google Scholar] [CrossRef]
  11. Luo, P.; Wen, P.; Bai, H.Y.; Ruta, B.; Wang, W. Relaxation decoupling in metallic glasses at low temperatures. Phys. Rev. Lett. 2017, 118, 225901. [Google Scholar] [CrossRef] [PubMed]
  12. Wang, T.; Wang, L.; Wang, Q.; Liu, Y.; Hui, X. Pronounced plasticity caused by phase separation and β-relaxation synergistically in Zr–Cu–Al–Mo bulk metallic glasses. Sci. Rep. 2017, 7, 1238. [Google Scholar] [CrossRef] [PubMed]
  13. Wang, T.; Wu, Y.; Si, J.; Liu, Y.; Hui, X. Plasticizing and work hardening in phase separated Cu-Zr-Al-Nb bulk metallic glasses by deformation induced nanocrystallization. Mater. Des. 2018, 142, 74–82. [Google Scholar] [CrossRef]
  14. Ketov, S.V.; Sun, Y.; Nachum, S.; Lu, Z.; Checchi, A.; Beraldin, A.R.; Bai, H.; Wang, W.; Louzguine-Luzgin, D.V.; Carpenter, M.A.; et al. Rejuvenation of metallic glasses by non-affine thermal strain. Nature 2015, 524, 200–203. [Google Scholar] [CrossRef]
  15. Song, W.; Lu, X. Improving plasticity of the Zr46Cu46Al8 bulk metallic glass via thermal rejuvenation. Sci. Bull. 2018, 63, 840–844. [Google Scholar] [CrossRef]
  16. Hu, Z.; Zhao, Z.; Hu, Y.; Xing, J.; Lu, T.; Wei, B. Effect of ion irradiation on mechanical behaviors of Ti40Zr25Be30Cr5 bulk metallic glass. Mater. Res. 2012, 15, 713–717. [Google Scholar] [CrossRef]
  17. Cao, Y.; Xie, X.; Antonaglia, J.; Winiarski, B.; Wang, G.; Shin, Y.C.; Withers, P.J.; Dahmen, K.A.; Liaw, P.K. Laser shock peening on Zr-based bulk metallic glass and its effect on plasticity: Experiment and modeling. Sci. Rep. 2015, 5, 10789. [Google Scholar] [CrossRef]
  18. Ichitsubo, T.; Matsubara, E.; Kai, S.; Hirao, M. Ultrasound-induced crystallization around the glass transition temperature for Pd40Ni40P20 metallic glass. Acta Mater. 2004, 52, 423–429. [Google Scholar] [CrossRef]
  19. Ichitsubo, T.; Matsubara, E.; Yamamoto, T.; Chen, H.; Nishiyama, N.; Saida, J.; Anazawa, K. Microstructure of fragile metallic glasses inferred from ultrasound-accelerated crystallization in Pd-based metallic glasses. Phys. Rev. Lett. 2005, 95, 245501. [Google Scholar] [CrossRef]
  20. Ma, C.; Qin, H.; Ren, Z.; O’Keeffe, S.C.; Stevick, J.; Doll, G.L.; Dong, Y.; Winiarski, B.; Ye, C. Increasing fracture strength in bulk metallic glasses using ultrasonic nanocrystal surface modification. J. Alloys Compd. 2017, 718, 246–253. [Google Scholar] [CrossRef]
  21. Zhu, Z.; Gu, L.; Xie, G.; Zhang, W.; Inoue, A.; Zhang, H.; Hu, Z. Relation between icosahedral short-range ordering and plastic deformation in Zr–Nb–Cu–Ni–Al bulk metallic glasses. Acta Mater. 2011, 59, 2814–2822. [Google Scholar] [CrossRef]
  22. Salivar, G.C.; Goree, J.G. The applicability of ASTM standard test specimens to fracture and fatigue crack growth of discontinuous-fiber composites. J. Test. Eval. 1998, 26, 336–345. [Google Scholar] [CrossRef]
  23. Qin, F.; Wang, X.; Inoue, A. Effect of annealing on microstructure and mechanical property of a Ti–Zr–Cu–Pd bulk metallic glass. Intermetallics 2007, 15, 1337–1342. [Google Scholar] [CrossRef]
  24. Fan, C.; Louzguine, D.V.; Li, C.; Inoue, A. Nanocrystalline composites with high strength obtained in Zr–Ti–Ni–Cu–Al bulk amorphous alloys. Appl. Phys. Lett. 1999, 75, 340–342. [Google Scholar] [CrossRef]
  25. Xing, L.; Bertrand, C.; Dallas, J.-P.; Cornet, M. Nanocrystal evolution in bulk amorphous Zr57Cu20Al10Ni8Ti5 alloy and its mechanical properties. Mater. Sci. Eng. A 1998, 241, 216–225. [Google Scholar] [CrossRef]
  26. Zhai, W.; Wang, B.; Liu, H.; Hu, L.; Wei, B. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy. Sci. Rep. 2019, 6, 36718. [Google Scholar] [CrossRef]
  27. Greer, A.L.; Cheng, Y.; Ma, E. Shear bands in metallic glasses. Mater. Sci. Eng. R 2013, 74, 71–132. [Google Scholar] [CrossRef]
  28. Qu, R.; Liu, Z.; Wang, G.; Zhang, Z. Progressive shear band propagation in metallic glasses under compression. Acta Mater. 2015, 91, 19–33. [Google Scholar] [CrossRef]
  29. Nieh, T.G.; Yang, Y.; Lu, J.; Liu, C. Effect of surface modifications on shear banding and plasticity in metallic glasses: An overview. Prog. Nat. Sci. Mater. Int. 2012, 22, 355–363. [Google Scholar] [CrossRef]
  30. Takeuchi, A.; Inoue, A. Classification of bulk metallic glasses by atomic size difference, heat of mixing and period of constituent elements and its application to characterization of the main alloying element. Mater. Trans. 2005, 46, 2817–2829. [Google Scholar] [CrossRef]
  31. Chen, S.; Zhang, H.; Todd, I. Phase-separation-enhanced plasticity in a Cu47.2Zr46.5Al5.5Nb0.8 bulk metallic glass. Scr. Mater. 2014, 72–73, 47–50. [Google Scholar] [CrossRef]
  32. Zhang, L.; Wang, T.; Hou, Q.; Hao, Q.; Qiao, J. Deformation-induced microstructural heterogeneity and rejuvenation in a Zr-based bulk metallic glass. J. Non-Cryst. Solids 2021, 574, 121148. [Google Scholar] [CrossRef]
  33. Nomoto, K.; Ceguerra, A.V.; Gammer, C.; Li, B.; Bilal, H.; Hohenwarter, A.; Gludovatz, B.; Eckert, J.; Ringer, S.P.; Kruzic, J.J. Medium-range order dictates local hardness in bulk metallic glasses. Mater. Today 2021, 44, 48–57. [Google Scholar] [CrossRef]
Figure 1. X-ray diffraction patterns for the as-cast samples alongside those subjected to ultrasonication for durations of 15 and 30 min.
Figure 1. X-ray diffraction patterns for the as-cast samples alongside those subjected to ultrasonication for durations of 15 and 30 min.
Metals 15 00683 g001
Figure 2. DSC curves of the as-cast and ultrasonic samples at a heating rate of 5 K/min.
Figure 2. DSC curves of the as-cast and ultrasonic samples at a heating rate of 5 K/min.
Metals 15 00683 g002
Figure 3. Load-line displacement curves of the as-cast and ultrasonic samples (treated for 15 and 30 min) under three-point bending tests.
Figure 3. Load-line displacement curves of the as-cast and ultrasonic samples (treated for 15 and 30 min) under three-point bending tests.
Metals 15 00683 g003
Figure 4. Overall SEM images of Zr58.75Cu21.15Fe4.7Al9.4Nb6 BMG after three-point bending: (a) as-cast; (b) ultrasonic sample treated for 30 min.
Figure 4. Overall SEM images of Zr58.75Cu21.15Fe4.7Al9.4Nb6 BMG after three-point bending: (a) as-cast; (b) ultrasonic sample treated for 30 min.
Metals 15 00683 g004
Figure 5. Transmission electron microscopy images and selected area electron diffraction patterns: (a) bright-field TEM image along with its associated SAED pattern for the as-cast specimen; (b) bright-field TEM image of the sample treated with ultrasonication for 30 min.
Figure 5. Transmission electron microscopy images and selected area electron diffraction patterns: (a) bright-field TEM image along with its associated SAED pattern for the as-cast specimen; (b) bright-field TEM image of the sample treated with ultrasonication for 30 min.
Metals 15 00683 g005aMetals 15 00683 g005b
Figure 6. High-resolution transmission electron microscopy images: (a) high-resolution TEM image for the as-cast specimen; (b) high-resolution TEM image of the sample treated with ultrasonication for 30 min.
Figure 6. High-resolution transmission electron microscopy images: (a) high-resolution TEM image for the as-cast specimen; (b) high-resolution TEM image of the sample treated with ultrasonication for 30 min.
Metals 15 00683 g006
Figure 7. Bright-field TEM image and elemental mapping: (a) bright-field TEM image of the deformed ultrasonic sample treated for 30 min; the elemental mapping of (b) Zr, (c) Cu, (d) Fe, (e) Al, and (f) Nb; (g) elemental line scanning image along the blue arrow in (a).
Figure 7. Bright-field TEM image and elemental mapping: (a) bright-field TEM image of the deformed ultrasonic sample treated for 30 min; the elemental mapping of (b) Zr, (c) Cu, (d) Fe, (e) Al, and (f) Nb; (g) elemental line scanning image along the blue arrow in (a).
Metals 15 00683 g007aMetals 15 00683 g007b
Figure 8. Schematic diagram of mechanism of ultrasonic treatment.
Figure 8. Schematic diagram of mechanism of ultrasonic treatment.
Metals 15 00683 g008
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Chen, X.; Zhang, Z.; Wang, T.; Li, Y.; Bai, R.; Wang, M.; Hui, X. Enhancing Fracture Toughness, Strength and Ductility of Zr58.75Cu21.15Fe4.7Al9.4Nb6 Bulk Metallic Glass via Ultrasound Excitation Technique. Metals 2025, 15, 683. https://doi.org/10.3390/met15060683

AMA Style

Chen X, Zhang Z, Wang T, Li Y, Bai R, Wang M, Hui X. Enhancing Fracture Toughness, Strength and Ductility of Zr58.75Cu21.15Fe4.7Al9.4Nb6 Bulk Metallic Glass via Ultrasound Excitation Technique. Metals. 2025; 15(6):683. https://doi.org/10.3390/met15060683

Chicago/Turabian Style

Chen, Xiaoming, Zhe Zhang, Tuo Wang, Yuluo Li, Rui Bai, Mingming Wang, and Xidong Hui. 2025. "Enhancing Fracture Toughness, Strength and Ductility of Zr58.75Cu21.15Fe4.7Al9.4Nb6 Bulk Metallic Glass via Ultrasound Excitation Technique" Metals 15, no. 6: 683. https://doi.org/10.3390/met15060683

APA Style

Chen, X., Zhang, Z., Wang, T., Li, Y., Bai, R., Wang, M., & Hui, X. (2025). Enhancing Fracture Toughness, Strength and Ductility of Zr58.75Cu21.15Fe4.7Al9.4Nb6 Bulk Metallic Glass via Ultrasound Excitation Technique. Metals, 15(6), 683. https://doi.org/10.3390/met15060683

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop