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1. Corrosion behavior of an in situ consolidated nanocrystalline Al-V alloy

   https://doi.org/10.1038/s41529-022-00225-5  

   Witharamage, C. S.; Christudasjustus, J.; Smith, J.; Gao, W.; Gupta, R. K. (February 2022, npj Materials Degradation)

   Abstract Supersaturated solid solutions of Al and corrosion-resistant alloying elements (M: V, Mo, Cr, Ti, Nb), produced by non-equilibrium processing techniques, have been reported to exhibit high corrosion resistance and strength. The corrosion mechanism for such improved corrosion performance has not been well understood. We present a fundamental understanding of the role of V in corrosion of an Al-V alloy, which will provide a theoretical background for developing corrosion-resistant Al alloys. High-energy ball milling of the elemental powder of Al and V produced an in situ consolidated Al-V alloy, which exhibited high solid solubility of V. The corrosion resistance of Al-V alloy was significantly higher than that of pure Al, which was attributed to the (1) enrichment of V at the passive film/substrate interface, (2) incorporation of V into the passive film, and (3) deposition of V on the iron-containing cathodic particles and therefore, retardation of cathodic reaction. 

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2. Spontaneous passivation in a Rare-Earth-Free Mg4(TiZnSn)3 Multi-Principal element alloy

   https://doi.org/10.1007/s42247-025-01203-8  

   Helmer, Alexander T; Gupta, Rajeev K (August 2025, Emergent Materials)

   Abstract Mg₄(TiZnSn)₃, a rare-earth-free Mg-based multi-principal element alloy, was synthesized via high-energy ball milling and cold compaction. Potentiodynamic polarization in 0.1 M NaCl revealed spontaneous passivation with a corrosion current density of 8.96 ± 0.83 µA/cm²and a nobler than Mg corrosion potential of -1058.35 ± 15.91 mV_SCE. X-ray photoelectron spectroscopy confirmed the formation of a mixed oxide film containing ZnO, SnO₂, and TiO₂, contributing to the observed passivity. The alloy also exhibited improved mechanical performance, with a hardness of 5.06 ± 0.41 GPa and Young’s modulus of 109.24 ± 10 GPa. These results demonstrate that tailored multi-element alloying and powder metallurgy can synergistically enhance both corrosion resistance and mechanical properties in Mg alloys. 

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3. Corrosion Behavior and Hardness of Binary Mg Alloys Produced via High-Energy Ball-Milling and Subsequent Spark Plasma Sintering

   https://doi.org/10.5006/3633  

   Farooq Khan, Mohammad Umar; Larimian, Taban; Borkar, T.; Gupta, R.K. (November 2020, Corrosion)

   null (Ed.)

   In this work, nine nanocrystalline binary Mg alloys were synthesized by high-energy ball milling. The compositions, Mg-5 wt% M (M-Cr, Ge, Mn, Mo, Ta, Ti, V, Y, and Zn), were milled with the objective of achieving non-equilibrium alloying. The milled alloys were consolidated via cold compaction (CC) at 25°C and spark plasma sintering (SPS) at 300°C. X-ray diffraction (XRD) analysis indicated grain refinement below 100 nm, and the scanning electron microscopy revealed homogeneous microstructures for all compositions. XRD analysis revealed that most of the alloys showed a change in the lattice parameter, which indicates the formation of a solid solution. A significant increase in the hardness compared to unmilled Mg was observed for all of the alloys. The corrosion behavior was improved in all of the binary alloys compared to milled Mg. A significant decrease in the cathodic kinetics was evident due to Ge and Zn additions. The influence of the alloying elements on corrosion behavior has been categorized and discussed based on the electrochemical response of their respective binary Mg alloys. 

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4. Corrosion Behavior of MgTiZn and Mg4TiZn Alloys After Ball Milling and Subsequent Spark Plasma Sintering

   https://doi.org/10.3390/ma18143279  

   Helmer, Alexander; Agrawal, Rahul; Mugale, Manoj; Borkar, Tushar; Gupta, Rajeev (July 2025, Materials)

   Magnesium-containing multi-principal element alloys (MPEAs) are promising for lightweight applications due to their low density, high specific strength, and biocompatibility. This study examines two Mg-Ti-Zn alloy compositions, equal molar MgTiZn (TZ) and Mg4TiZn (4TZ), synthesized via ball milling followed by spark plasma sintering, focusing on their microstructures and corrosion behaviors. X-ray diffraction and transmission electron microscopy revealed the formation of intermetallic phases, including Ti2Zn and Mg21Zn25 in TZ, while 4TZ exhibited a predominantly Mg-rich phase. Potentiodynamic polarization and immersion tests in 0.1 M NaCl solution showed that both alloys had good corrosion resistance, with values of 3.65 ± 0.65 µA/cm2 for TZ and 4.58 ± 1.64 µA/cm2 for 4TZ. This was attributed to the formation of a TiO2-rich surface film in the TZ, as confirmed by X-ray photoelectron spectroscopy (XPS), which contributed to enhanced passivation and lower corrosion current density. Both alloys displayed high hardness, 5.5 ± 1.0 GPa for TZ and 5.1 ± 0.9 GPa for 4TZ, and high stiffness, with Young’s modulus values of 98.2 ± 11.2 GPa for TZ and 100.8 ± 9.6 GPa for 4TZ. These findings highlight the potential of incorporating Ti and Zn via mechanical alloying to improve the corrosion resistance of Mg-containing MPEAs and Mg-based alloys. 

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5. High-Photovoltage Silicon Nanowire for Biological Cofactor Production

   https://doi.org/10.1021/jacs.3c06243  

   Lineberry, Elizabeth; Kim, Jinhyun; Kim, Jimin; Roh, Inwhan; Lin, Jia-An; Yang, Peidong (September 2023, Journal of the American Chemical Society)

   Photocathodic conversion of NAD+ to NADH cofactor is a promising platform for activating redox biological catalysts and enzymatic synthesis using renewable solar energy. However, many photocathodes suffer from low photovoltage, consequently requiring a high cathodic bias for NADH production. Here, we report an n+p-type silicon nanowire (n+p-SiNW) photocathode having a photovoltage of 435 mV to drive energy-efficient NADH production. The enhanced band bending at the n+/p interface accounts for the high photovoltage, which conduces to a benchmark onset potential [0.393 V vs the reversible hydrogen electrode (VRHE)] for SiNW-based photocathodic NADH generation. In addition, the n+p-SiNW nanomaterial exhibits a Faradaic efficiency of 84.7% and a conversion rate of 1.63 μmol h–1 cm–1 at 0.2 VRHE, which is the lowest cathodic potential to achieve the maximum productivity among SiNW-sensitized cofactor production. 

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