More Like this

1. Low-frequency conductivity of low wear high-entropy alloys

   https://doi.org/10.1038/s41467-024-49035-0  

   Yeh, Cheng-Hsien; Hsu, Wen-Dung; Liu, Bernard Haochih; Yang, Chan-Shan; Kuan, Chen-Yun; Chang, Yuan-Chun; Huang, Kai-Sheng; Jhang, Song-Syun; Lu, Chia-Yen; Liaw, Peter K; et al (December 2024, Nature Communications)

   Abstract High-entropy alloys (HEAs) provide new research avenues for alloy combinations in the periodic table, opening numerous possibilities in novel-alloy applications. However, their electrical characteristics have been relatively underexplored. The challenge in establishing an HEA electrical conductivity model lies in the changes in electronic characteristics caused by lattice distortion and complexity of nanostructures. Here we show a low-frequency electrical conductivity model for the Nb-Mo-Ta-W HEA system. The cocktail effect is found to explain trends in electrical-conductivity changes in HEAs, while the magnitude of the reduction is understood by the calculated plasma frequency, free electron density, and measured relaxation time by terahertz spectroscopy. As a result, the refractory HEA Nb₁₅Mo₃₅Ta₁₅W₃₅thin film exhibits both high hardness and excellent conductivity. This combination of Nb₁₅Mo₃₅Ta₁₅W₃₅makes it suitable for applications in atomic force microscopy probe coating, significantly improving their wear resistance and atomic-scale image resolution. 

   more » « less
2. Low-Latency In-Band Integration of Multiple Low-Power Wide-Area Networks

   https://doi.org/10.1109/RTAS52030.2021.00034  

   Modekurthy, Venkata P.; Ismail, Dali; Rahman, Mahbubur; Saifullah, Abusayeed (May 2021, 2021 IEEE 27th Real-Time and Embedded Technology and Applications Symposium (RTAS))

   null (Ed.)
3. Low-cost and low-topography fabrication of multilayer interconnections for microfluidic devices

   https://doi.org/10.1088/1361-6439/ab8c9e  

   Li, Jia; Chen, Supin; Kim, Chang-Jin (May 2020, Journal of Micromechanics and Microengineering)
4. Low-temperature rheology of calcite

   https://doi.org/10.1093/gji/ggz577  

   Sly, Michael K.; Thind, Arashdeep S.; Mishra, Rohan; Flores, Katharine M.; Skemer, Philip (December 2019, Geophysical Journal International)

   SUMMARY Low-temperature plastic rheology of calcite plays a significant role in the dynamics of Earth's crust. However, it is technically challenging to study plastic rheology at low temperatures because of the high confining pressures required to inhibit fracturing. Micromechanical tests, such as nanoindentation and micropillar compression, can provide insight into plastic rheology under these conditions because, due to the small scale, plastic deformation can be achieved at low temperatures without the need for secondary confinement. In this study, nanoindentation and micropillar compression experiments were performed on oriented grains within a polycrystalline sample of Carrara marble at temperatures ranging from 23 to 175 °C, using a nanoindenter. Indentation hardness is acquired directly from nanoindentation experiments. These data are then used to calculate yield stress as a function of temperature using numerical approaches that model the stress state under the indenter. Indentation data are complemented by uniaxial micropillar compression experiments. Cylindrical micropillars ∼1 and ∼3 μm in diameter were fabricated using a focused ion beam-based micromachining technique. Yield stress in micropillar experiments is determined directly from the applied load and micropillar dimensions. Mechanical data are fit to constitutive flow laws for low-temperature plasticity and compared to extrapolations of similar flow laws from high-temperature experiments. This study also considered the effects of crystallographic orientation on yield stress in calcite. Although there is a clear orientation dependence to plastic yielding, this effect is relatively small in comparison to the influence of temperature. 

   more » « less
5. What makes low-frequency earthquakes low frequency

   https://doi.org/10.1126/sciadv.adh3688  

   Wang, Qing-Yu; Frank, William B.; Abercrombie, Rachel E.; Obara, Kazushige; Kato, Aitaro (August 2023, Science Advances)

   Low-frequency earthquakes, atypical seismic events distinct from regular earthquakes, occur downdip of the seismogenic megathrust where an aseismic rheology dominates the subduction plate boundary. Well situated to provide clues on the slip regime of this unique faulting environment, their distinctive waveforms reflect either an unusual rupture process or unusually strong attenuation in their source zone. We take advantage of the unique geometry of seismicity in the Nankai Trough to isolate the spectral signature of low-frequency earthquakes after correcting for empirically derived attenuation. We observe that low-frequency earthquake spectra are consistent with the classical earthquake model, yet their rupture duration and stress drop are orders of magnitude different from ordinary earthquakes. We conclude their low-frequency nature primarily results from an atypical seismic rupture process rather than near-source attenuation. 

   more » « less