Structure and magnetic properties of a multi-principal element Ni–Fe–Cr–Co–Zn–Mn alloy

A nanocrystalline alloy with a nominal composition of Ni₂₀Fe₂₀Cr₂₀Co₂₀Zn₁₅Mn₅ was produced by mechanical alloying and processed using annealing treatments between 450 and 600 °C for lengths from 0.5 to 4 h. Analysis was conducted using x-ray diffraction, transmission electron microscopy, magnetometry, and first-principles calculations. Despite designing the alloy using empirical high-entropy alloy guidelines, it was found to precipitate numerous phases after annealing. These precipitates included a magnetic phase, α-FeCo, which, after the optimal heat treatment conditions of 1 h at 500 °C, resulted in an alloy with reasonably good hard magnetic properties. The effect of annealing temperature and time on the microstructure and magnetic properties are discussed, as well as the likely mechanisms that cause the microstructure development.     

Influence of the order-disorder transition on the magnetic properties of Fe75Al25-xSix alloys

The influence of the different crystal structures and the variation of the lattice parameter on the evolution of the magnetism in the order-disorder transition produced by crushing and mechanical milling in the intermetallic Fe₇₅Al_25-xSi_x alloys (x = 7.5, 12.5, 17.5, 25) has been systematically studied by means of XRD measurements, Mössbauer spectroscopy and magnetic measurements. The results indicate that with the addition of Si to binary Fe₇₅Al₂₅ alloy the mechanical deformation needed to disorder the alloys increases. At the same time the variation of the lattice parameter due to the disorder is reduced as Si is added. The magnetic measurements indicate that there is a complex behaviour in ternary alloys with an opposite influence of Si and Al during the order-disorder transition. However, when the transition is fulfilled there is a linear relationship between structural and magnetic parameters.     

The link between operational practices and specific energy consumption in metal ore milling plants – Ontario experiences

An energy audit was conducted on a base metal milling facility where a top-down, bottom-up approach was presented to balance data measurements and estimates. The relation between throughput and specific electricity consumption, presented as a part-load efficiency curve for a milling operation, was established from the audit data. Unsurprisingly, the most efficient use of electricity occurred when the mill was operating at design capacity, but a survey of 14 metal mills operating in Ontario showed that 12 were operated under design capacity during 2012. For base metal flotation mills, 16–36% electricity cost savings could be realized by modification to the operating schedule, which would ensure that these facilities operated at design capacity even if plant operation was intermittent. With the Ontario electricity tariff arrangements, additional cost savings from strategic scheduling could reduce demand during coincident peak hours, which could provide financial benefit to these milling facilities.     

2195铝锂合金碱性化学铣切工艺探究

初步研究了2195铝锂合金碱性化学铣切(简称化铣)工艺。结果表明,在一定条件下,通过添加一定浓度的添加剂A、B和C,2195铝锂合金平板试片化铣均匀性好,化铣速度为0.0297mm/min,侧切率为0.988,粗糙度基本保持不变。研究结果对2195铝锂合金产品化铣加工工艺优化可提供参考。     

高容量硅基负极材料及其厚膜成型技术和性能

为了缓解硅基负极材料的体积膨胀并改善其电化学性能，以Mg、SiO和石墨为原料，成功制备出一种多相Si-MgO-G复合材料。探讨了不同高能球磨工艺对Mg和SiO反应程度的影响及厚膜成型技术的应用。结果表明，当高能球磨（1+5）h后，Mg和SiO原位反应生成Si-MgO产物，将反应产物与石墨混磨制备成多相Si-MgO-G复合材料。用XRD、SEM 和TEM等手段对制得材料的结构、形貌和成分进行分析，证实了复合材料是由Si、MgO和石墨组成，其中Si(220)//MgO(200)之间存在晶面共格关系。用CV和EIS等对捏合开炼厚膜技术制得负极极片进行电化学性能分析，结果表明，捏合开炼工艺制备的厚膜极片的厚度、载量和面积比容量分别约为薄膜极片的7.4倍、6.0倍和6.2倍。采用简单、绿色和可规模化生产的厚电极制备技术，可提高锂离子电池的面积比容量。     

VO2-ZnO composite films with enhanced thermochromic properties for smart windows

VO₂ film is a promising thermochromic material in smart windows due to its reversible metal to insulator transition (MIT) accompanied with an abrupt change of transmittance in near-infrared region at around 68 °C (T>68 °C, translucent; T < 68 °C, transparent), but which has not been widely applied because its low luminous transmittance (<60%) and solar modulation efficiency (<10%) are difficult to be improved simultaneously. In order to solve this problem, the ZnO-VO₂ composite film was prepared by a facile method, in which commercial ZnO nanoparticles (NPs) and VO₂ micro-particles were mixed by ball milling method to form the composites. By introducing ZnO NPs into the composite film, the luminous transmittance (T_lum) of the composite film was increased by 16.9% (from 54.9% to 63.9%) and the solar modulation efficiency (ΔT_sol) was increased by 14.1% (from 9.9% to 11.3%) compared to the pure VO₂ composite film. This was because ZnO NPs not only played the role of antireflection, but also prevented VO₂ particles from agglomeration by dispersing around VO₂ particles. Furthermore, the two-layered film based on ZnO-VO₂ composites exhibited an astonishing ΔT_sol of 18.8%, while maintaining excellent T_lum of 54.3%. This work could provide a simple and novel idea for us to improve the thermochromic properties of VO₂ films and simultaneously to promote their practical application.     

One-step scalable preparation of graphene nanosheets and high-thermal-conductivity flexible graphene films

It is well known that graphene nanosheets (GNSs) have many excellent properties. However, it has been a difficult thing to exfoliate graphite into GNSs in a controllable and scalable manner. In this research, a new strategy named xylitol-assisted ball milling exfoliation (XABME) was developed for the scalable preparation of GNSs. The experimental results characterized by a series of measurements showed that GNSs were successfully exfoliated by the XABME strategy. The structure of the prepared nanosheets was featured by large lateral size and ultra-small thickness. Furthermore, the prepared GNSs easily achieved high production yield (≈54%). Lastly, the as-obtained GNSs and cellulose nanofibers (CNF) were compounded to form some nanomaterial films. The prepared films exhibited excellent flexibility and higher thermal conductivity, with the in-plane thermal conductivity of 90 wt% GNS film (8.0 W/(m·K)) being 11.4 times higher than that of the film without GNSs. This shows that GNSs could effectively enhance the thermal conductivity of the CNF matrix and indicate that these prepared films have great potentials in the thermal management of portable mobile devices.     

Characteristics of tiger nut milk: effects of milling

A standard method for the extraction of tiger nut milk has been introduced. It has been shown that, although milling duration improves the yield of tiger nut milk solids and its nutrient composition, there is a quantifiable loss of nutrient in the pressing residue during milk extraction. Milling duration improved the colloidal stability of the milk against creaming during 16 h of storage. A higher milling intensity resulted in the aggregation of biological polymers which resulted in colloidal destabilisation. Milling improved the lightness and stability and reduced browning rate of the tiger nut milk during storage. This report is important for the production of tiger nut milk of consistent and comparable characteristics. Milling has been introduced as a processing method for the qualitative and quantitative modulation of the properties of tiger nut milk. It is recommended to develop further strategies to improve the colloidal stability of tiger nut milk as a beverage.     

Phase-evolution in high entropy alloys: Role of synthesis route

Synthesis route can have a significant influence on the process of phase-choice and -evolution in High Entropy Alloys (HEAs). With the objective of instituting awareness, this communication on the foundation of phase diagrams, adopted using the CALPHAD approach, attempts at describing and deciphering the cause for such gradation.