image: Aging-Assisted UV Loading
Credit: Jiang Ma, Shuai Ren and Jianyu Chen from Shenzhen University.
A research team led by Jiang Ma from Shenzhen University, China, has developed a novel technique to enhance the plasticity of metallic glasses. By leveraging a combination of controlled aging processes and ultrasonic vibrations, they have demonstrated the ability to reverse aging-induced property deterioration and significantly improve the capacity of these glasses to deform without breaking. The team demonstrated that aged samples completely lose their compressive plasticity, whereas UV treatment after aging not only restores it but enhances the plasticity beyond that of the as-cast one.
This finding breaks through the traditional perception of aging effects and opens up a new research direction for more durable and versatile applications of MGs in various industries.
Metallic glasses (MGs) are a unique class of amorphous metals characterized by their disordered atomic structures, which confer exceptional mechanical properties such as high strength, elasticity, and corrosion resistance. These materials have attracted significant interest for diverse applications, including structural components, electronic devices, and biomedical implants. However, despite their advantageous properties, MGs face critical challenges that hinder their practical deployment. One major obstacle is their susceptibility to aging, a natural process where the atomic arrangement gradually relaxes into a more stable, lower-energy state over time. This aging leads to a deterioration in ductility and plasticity, making the materials more fragile and less capable of sustaining deformation without fracture.
Traditionally, efforts to rejuvenate or restore the ductility of aged MGs have involved thermal treatments or mechanical processes, but these methods often require high energy input, lengthy procedures, or risk damaging the structural integrity of the glasses.
MGs are fabricated by quenching glass-forming metallic liquids at relatively high cooling rates to prevent crystallization. Owing to their unique amorphous structure, MGs exhibit superior properties such as large elastic limits, high strength, good wear resistance, and remarkable soft magnetic properties. However, their inherent brittleness has limited their applications. Moreover, shaping MGs into desired components often involves thermo-plastic deformation, which requires heating the sample to the supercooled liquid region. However, this heating process significantly exacerbates the aging effect, leading to a rapid deterioration in properties, particularly in terms of plasticity. This greatly restricts their processing and applications. Therefore, finding ways to mitigate the effect caused by aging is a critical challenge in this field.
The Results: Taking this in mind, a group of researchers found that ultrasonic vibration (UV) treatment can effectively reverse aging in MGs. within just half a second, restoring and even surpassing original levels of plasticity. They revealed that UV treatment can rejuvenate aged Zr-based MGs in just 0.5 seconds, restoring and even enhancing their plasticity to 14.5%, 1.5 times greater than their original as-cast state. This rapid, efficient recovery marks a major improvement over conventional aging reversal method. The research uncovers the structural basis for this rejuvenation, showing that UV treatment induces a higher energy, disordered atomic state associated with “anti-free volume defects”, a densely packed regions that improve atomic mobility and facilitate deformation. This disorder directly correlates with improved mechanical properties, offering a key insight into how vibrational energy reshapes the atomic structure of these glasses.
An innovative and counterintuitive approach was also introduced by the researchers: the pre-aging the MGs and subsequent UV treatment can improve ductility of the glasses.
The Impact: The findings offer a transformative, low-cost alternative to traditional rejuvenation methods, enabling fast and damage-free recovery of aged MGs. This technique could greatly extend the lifespan and reliability of MG components in structural, biomedical, and electronic applications.
Beyond practical applications, the study establishes a new paradigm for tailoring amorphous materials by linking vibrational energy input to atomic-level structural changes and macroscopic properties.
The Future: This work demonstrates that aging is no longer a detrimental process, but an essential prerequisite to improve plasticity MGs after UV treatment. This finding breaks through the traditional perception of aging effects and opens up a a novel path for designing MGs with customizable mechanical performance, opening exciting directions for future research and processing techniques across various amorphous and metastable materials.
From a theoretical standpoint, the anti-free volume defect framework offers a compelling explanation for our experimental observations. However, the direct experimental evidence for these defects remains elusive, representing a critical gap in our understanding of their structural manifestation. Future studies are needed to obtain direct evidence for the formation of anti-free volume defects through molecular dynamics simulations or positron annihilation spectroscopy. Such investigations will not only validate the anti-free volume defects, but also offer critical insights into the atomic-scale mechanisms governing defect-mediated plasticity in MGs.
From a broader perspective, this strategy offers new possibilities for the functional application of amorphous alloys and may potentially be extended to multiple functional material fields, such as catalytic performance modulation (in Pd-based or Pt-based MGs) and soft magnetic property optimization (in Fe-based MGs), holding significant scientific and application value. Moreover, the relationship between the energy threshold exhibited in this work and the amorphous composition, as well as the long-term stability of the samples after ultrasonic treatment, still warrant further investigation.
This research has been recently published in the online edition of Materials Futures, a prominent international journal in the field of interdisciplinary materials science research.
Reference: Jianyu Chen, Shuai Ren, Zhe Chen, Jie Dong, Zhichao Lu, Jiahua Zhu, Lixing Zhu, Yangguang Zhan, Xingran Zhao, Wenxue Wang, Shenghao Zeng, Jing Xiao, Sajad Sohrabi, Xiong Liang, Ke Yang, Dong Ma, Jiang Ma. Plasticity Enhancement in Metallic Glasses via Aging-assisted Ultrasonic Vibrations[J]. Materials Futures. DOI: 10.1088/2752-5724/adeeae
Journal
Materials Futures