High-entropy induced a glass-to-glass transition in a metallic glass.

Glass-to-glass transitions are useful for us to understand the glass nature, but it remains difficult to tune the metallic glass into significantly different glass states. Here, we have demonstrated that the high-entropy can enhance the degree of disorder in an equiatomic high-entropy metallic glass NbNiZrTiCo and elevate it to a high-energy glass state. An unusual glass-to-glass phase transition is discovered during heating with an enormous heat release even larger than that of the following crystallization at higher temperatures. Dramatic atomic rearrangement with a short- and medium-range ordering is revealed by in-situ synchrotron X-ray diffraction analyses. This glass-to-glass transition leads to a significant improvement in the modulus, hardness, and thermal stability, all of which could promote their applications. Based on the proposed high-entropy effect, two high-entropy metallic glasses are developed and they show similar glass-to-glass transitions. These findings uncover a high-entropy effect in metallic glasses and create a pathway for tuning the glass states and properties.

Influence of inorganic ions on degradation capability of Fe-based metallic glass towards dyeing wastewater remediation.

Metallic glasses (MGs) are promising candidates for catalysts with high efficiency for dyeing wastewater remediation, due to their metastable nature, disordered structure, and large residual stresses. However, dyeing wastewater usually contains a high concentration of inorganic ions which may have adverse effects on the degradation process, while the impacts of these ions on MGs' degradation capability have often been overlooked and still remain unknown. Thus, the roles of inorganic ions (Cl-, NO3-, SO42-, and H2PO4-) on the degradation of azo dye by Fe-based MG with nominal composition of Fe81Si4B14Cu1 were systematically investigated. The results showed that the inorganic ions have significant influence on MG's surface morphology, degradation capability, mineralization and durability. All these aspects need to be considered prior to application of MGs for azo dyes degradation in real natural contaminated water or saline wastewater.

One-pot preparation of nanoporous Ag-Cu@Ag core-shell alloy with enhanced oxidative stability and robust antibacterial activity.

Metallic core-shell nanostructures have inspired prominent research interests due to their better performances in catalytic, optical, electric, and magnetic applications as well as the less cost of noble metal than monometallic nanostructures, but limited by the complicated and expensive synthesis approaches. Development of one-pot and inexpensive method for metallic core-shell nanostructures' synthesis is therefore of great significance. A novel Cu network supported nanoporous Ag-Cu alloy with an Ag shell and an Ag-Cu core was successfully synthesized by one-pot chemical dealloying of Zr-Cu-Ag-Al-O amorphous/crystalline composite, which provides a new way to prepare metallic core-shell nanostructures by a simple method. The prepared nanoporous Ag-Cu@Ag core-shell alloy demonstrates excellent air-stability at room temperature and enhanced oxidative stability even compared with other reported Cu@Ag core-shell micro-particles. In addition, the nanoporous Ag-Cu@Ag core-shell alloy also possesses robust antibacterial activity against E. Coli DH5α. The simple and low-cost synthesis method as well as the excellent oxidative stability promises the nanoporous Ag-Cu@Ag core-shell alloy potentially wide applications.

Direct in situ observation of metallic glass deformation by real-time nano-scale indentation.

A common understanding of plastic deformation of metallic glasses (MGs) at room temperature is that such deformation occurs via the formation of runaway shear bands that usually lead to catastrophic failure of MGs. Here we demonstrate that inhomogeneous plastic flow at nanoscale can evolve in a well-controlled manner without further developing of shear bands. It is suggested that the sample undergoes an elasto-plastic transition in terms of quasi steady-state localized shearing. During this transition, embryonic shear localization (ESL) propagates with a very slow velocity of order of ~1 nm/s without the formation of a hot matured shear band. This finding further advances our understanding of the microscopic deformation process associated with the elasto-plastic transition and may shed light on the theoretical development of shear deformation in MGs.

A nanoglass alloying immiscible Fe and Cu at the nanoscale.

Synthesized from ultrafine particles with a bottom-up approach, nanoglasses are of particular importance in pursuing unique properties. Here, we design a metallic nanoglass alloy from two components of ∼Cu64Sc36 and ∼Fe90Sc10 nanoglasses. With nanoalloying mutually immiscible Fe and Cu, the properties of the nanoglass alloys can be tuned by varying the proportions of the ∼Fe90Sc10 component. This offers opportunity to create novel metallic glass nanocomposites and sheds light on building a structure-property correlation for the nanoglass alloys.

Highly uniform and reproducible surface enhanced Raman scattering on air-stable metallic glassy nanowire array.

Preparation of surface enhanced Raman scattering (SERS) nanostructures with both high sensitivity as well as high reproducibility has always been difficult and costly for routine SERS detection. Here we demonstrate air-stable metallic glassy nanowire arrays (MGNWAs), which were prepared by a cheap and rapid die nanoimprinting technique, could exhibit high SERS enhancement factor (EF) as well as excellent reproducibility. It shows that Pd(40.5)Ni(40.5)P(19) MGNWA with nanowires of 55 nm in diameter and 100 nm in pitch possesses high SERS activity with an EF of 1.1 × 10(5), which is 1-3 orders of magnitudes higher than that of the reported crystal Ni-based nanostructures, and an excellent reproducibility with a relative standard deviation of 9.60% measured by 121 points over an area of 100 µm*100 µm. This method offers an easy, rapid, and low-cost way to prepare highly sensitive and reproducible SERS substrates and makes the SERS more practicable.