Microstructure and Magnetocaloric Effect by Doping C in La-Fe-Si Ribbons

The melt-spun ribbons of LaFe11.5Si1.5Cx (x = 0, 0.1, 0.2, 0.3) compounds are prepared by the melt fast-quenching method. The doping of C is beneficial to the nucleation and precipitation of the La (Fe, Si)13 phase, which is indicated by the microstructure observation and the elemental analysis. Subsequently, the ribbons of LaFe11.5Si1.5C0.2 are annealed at different times, and the phase composition, the microstructures, and the magnetic properties are investigated. The LaFe11.5Si1.5C0.2 ribbons annealed at 1273 K for 2 h achieved the best magnetic properties, and the maximum isothermal magnetic entropy change with a value of 9.45 J/(kg·K) upon an applied field of 1.5 T at an increased Curie temperature 255 K.

An Ultrafast Active Quenching Active Reset Circuit with 50% SPAD Afterpulsing Reduction in a 28 nm FD-SOI CMOS Technology Using Body Biasing Technique

An ultrafast Active Quenching—Active Reset (AQAR) circuit is presented for the afterpulsing reduction in a Single Photon Avalanche Diode (SPAD). The proposed circuit is designed in a 28 nm Fully Depleted Silicon On Insulator (FD-SOI) CMOS technology. By exploiting the body biasing technique, the avalanche is detected very quickly and, consequently, is quenched very fast. The fast quenching decreases the avalanche charges, therefore resulting in the afterpulsing reduction. Both post-layout and experimental results are presented and are highly in accordance with each other. It is shown that the proposed AQAR circuit is able to detect the avalanche in less than 40 ps and reduce the avalanche charge and the afterpulsing up to 50%.

Structural Heterogeneity of an Amorpous Nanocrystalline Alloy in the Nanometer Range

An approach to describe the structure of amorphous alloys obtained by fast quenching from a melt, based on the fluctuation theory of phase transitions, is proposed in t in such objects.

Experimental investigation of slag/matte/metal/ tridymite equilibria in the Cu–Fe–O–S–Si system at 1473 K (1200°C), 1523 K (1250°C) and 1573 K (1300°C)

Laboratory experimental study was undertaken to characterise the four-phase slag/matte/metal/tridymite equilibria of the Cu-Fe-O-S-Si system at 1473 K [1200°C], 1523 K [1250° C] and 1573 [1300°C] in a "closed" system without interaction with gas phase. The research methodology involved high temperature equilibration, ultra-fast quenching of the equilibrated samples followed by quantitative measurement of the equilibrated phases by electron probe X-ray microanalysis. Attainment of chemical equilibrium was carefully checked by the 4-points test approach. The results obtained in the present study provide reliable fundamental experimental information, which is crucial for the development and optimisation of the multicomponent thermodynamic database for copper-containing systems.

Optical Properties of Bismuth Borate Glasses Doped with Zinc and Calcium Oxides

Some bismuth-borate oxide glass' samples were prepared by the fast quenching method, where B2O3 was replaced with equal concentrations of ZnO and CaO. X-ray diffraction (XRD) was used to examine the internal structure and Fourier transform infrared (FTIR) to identify building units and bonds throughout the studied structural matrices. XRD showed that all samples have short range order structural nature, while FTIR demonstrated some of Zn2+ acted as glass network formers and all Bi3+ acted as glass. UV-visible measurements and calculations showed a decreasing in the energy band gap from 3.83 eV to 1.73 eV with decreasing B2O3 content. Also with decreasing B2O3 content, both real refractive index and metallization factor decreased from 3.1 to 1.9 and from 0.56 to 0.71, respectively. For the studied glass' samples, density and molar volume showed inverted behaviors, where the density decreased while the molar volume increases with decreasing B2O3.

Influence of quench rate on multi-stage ageing of AA6014 alloy

The influence of quench rate after solution heat treatment on the microstructure in the as-quenched state and subsequent ageing kinetics of alloy AA6014 was investigated by means of transmission electron microscopy, positron annihilation lifetime spectroscopy and hardness measurements. Various ageing temperatures and stages were taken into consideration. Consistent with previous studies, we found that solute and vacancy supersaturation decrease during slow quenching due to precipitation and annihilation, respectively. Additionally, we observed cluster formation during cooling below 200 °C. As for the influence on ageing behaviour we observe different behaviour for high and low ageing temperature: Artificial ageing is more affected than pre-ageing and natural secondary ageing. The detrimental effect of natural ageing on paint-bake hardening also depends on the quench rate. Possible interpretations are associated with cluster formation during natural ageing and also during quenching. The influence of pre-ageing at different temperatures on subsequent ageing kinetics is similar for slower industrial-type quenching and for fast quenching, thus allowing to apply the findings from idealised quenching conditions to situations closer to real application.

Preparation of Ag nanoparticles by spark ablation in gas as catalysts for electrocatalytic hydrogen production

Spark ablation in gas (SAG) technology has the characteristics of being green, fast quenching, fast dynamics and specializes in producing metallic nanoparticles with a clean surface, small size, and abundant defects.