Development Of Al-B-C Master Alloy Under External Fields

This study investigates the application of external fields in the development of an Al-B-C alloy, with the aim of synthesizing in situ Al3BC particles. A combination of ultrasonic cavitation and distributive mixing was applied for uniform dispersion of insoluble graphite particles in the Al melt, improving their wettability and its subsequent incorporation into the Al matrix. Lower operating temperatures facilitated the reduction in the amount of large clusters of reaction phases, with Al3BC being identified as the main phase in XRD analysis. The distribution of Al3BC particles was quantitatively evaluated. Grain refinement experiments reveal that Al-B-C alloy can act as a master alloy for Al-4Cu and AZ91D alloys, with average grain size reduction around 50% each at 1wt%Al-1.5B-2C additions

Nanoscale phase changes in crystalline Ge2Sb2Te5 films using scanning probe microscopes

Nanoscale amorphous marks have been produced in crystalline Ge2Sb2Te5 films using an atomic-force microscope (AFM) and a scanning-tunneling microscope (STM) through electrical phase changes. Voltage pulses with duration of 5–100 ns applied by metal probes of the AFM and the STM can produce, respectively, high-resistance regions and deformations, the smallest sizes being ~10 and ~100 nm in diameter. Raman-scattering spectra demonstrate that these marks are amorphous. The AFM mark can be erased by applying longer pulses. Formation processes of the marks are considered from electrothermal and thermodynamic aspects

Refractive-diffractive hybrid optics array: comparative analysis of simulation and experiments

Hybrid optical elements, which combine refractive and diffractive optical components to enhance optical performance by taking advantage of the optical characteristics of the individual components, have enormous potential for next-generation optical devices. However, there have not been many reports on the simulation methodology to characterize such hybrid optical systems. Here, we present a method for simulating a hybrid optical element realized by attaching an ultra-thin, flexible diffractive optics array onto a refractive optical element. The ultra-thin diffractive optical element is fabricated by direct-laser-writing using a femtosecond pulsed laser as the light source. A systematic investigation of the proposed simulation method, which does not require extensive hardware resources or computational time, but retains resolution and accuracy, is presented. The proposed scheme is validated by comparing simulation and experimental results. The simulation and experimental results on the spot size and focal length for the diffractive Fresnel zone plate (FZP) match well, with typical errors of less than 6%. The aspect ratio of the focal spot sizes at the compound and FZP focal planes of the hybrid optical system from the simulation and experiment also match quite well, with typical errors below 7%. This simulation scheme will expedite the designs for novel hybrid optical systems with optimal optical performances for specific applications, such as microfluidics and aberration-controlled optics.Nanyang Technological UniversityThis work was financially supported by a research collaboration agreement by Panasonic Factory Solutions Asia Pacific (PFSAP) and Singapore Centre for 3D Printing (RCA15/027); National Research Foundation of the Republic of Korea (NRF-2012R1A3A1050386, 2020R1A2C2102338, 2021R1A4A1031660); Korea Forest Service (Korea Forestry Promotion Institute) through the R & D Program for Forest Science Technology (2020229C10-2022-AC01); and Basic Research Program funded by the Korea Institute of Machinery and Materials (NK224C)