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Co–Cr based alloys are recognized as one of the most widely used category of alloys amongst the biomedical materials. This is because these alloys show a high strength, corrosion resistance and good biocompatibility suitable for biomedical applications. Many researchers have been focused on the processing of these alloys using a selective laser melting process. The effects of different processing parameters on the obtained microstructural and mechanical properties of the processed parts have been investigated in these studies. However, the effect of powder distribution size (powder granulometry), as a primary processing parameter, on the microstructural and mechanical properties of Co–Cr alloys is not well investigated and studied so far. This study investigated the influence of this parameter, by using powders with the same composition and morphology but a different particle size of coarse and fine, on the microstructural and mechanical properties of as-built, homogenizing heat treated and homogenizing heat treated followed by subsequent aging treatment SLM fabricated Co28Cr9W1.5Si (wt.%) samples. X-ray diffraction, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy were used to characterize and identify the microstructure, phase composition and crystallographic information of the manufactured samples. Besides, the mechanical properties of samples, processed using powders having different size distributions, were measured using a tensile test machine and results were correlated to the microstructure of the samples. It was concluded that the powder granulometry has a negligible effect on the microstructural and mechanical properties of the as-built SLM Co–Cr–W–Si parts but a remarkable influence on those of the heat-treated ones. [ABSTRACT FROM AUTHOR]

Governments have implemented many regulations to solve traffic congestion and pollutant emissions. Traffic restriction (TR) policy is the most common and widely used traffic regulation. However, it is difficult to alleviate traffic pollution through TR policies. Only a few studies focus on TR policies in multiple cities. In this paper, we classify traffic restrictions by geographical factors and evaluate the impact of different policies based on PSM-DID first. Then, we classify the mixed restrictions and test their effects on air pollution. The results show that TR policy improves air quality regardless of the season. Moreover, the effect of TR policy is not affected by the superposition of the type of traffic restriction. For cities implementing the same TR policy, geographic factors can lead to different outcomes. This finding provides a reference for governments in reducing air pollution. • Traffic restrictions significantly affected air quality in different regions of China. • Cities implemented traffic restrictions have improved air quality in adjacent cities. • Effect of traffic restrictions does not depend on the number of mixed restrictions. [ABSTRACT FROM AUTHOR]

In this study, spherical Ni–Ti composite powder was synthesized from blended elemental Ni and Ti powders using radio frequency plasma spheroidization process. The effects of powder feeding rate and carrier gas flow rate on the spheroidization efficiency and Ni content of the obtained powders were investigated. The spherical Ni–Ti composite powder with a slightly Ti-rich composition was obtained at the optimal feeding rate of 35 g/min and carrier gas flow rate of 3 L/min. In addition to NiTi phase, elemental Ni and Ti powders were also identified in the produced powder. The prepared powder was adopted for laser powder bed fusion densification. Microcracks and pores were observed in the L-PBF-processed samples. In addition to NiTi main phase, un-melted elemental powders, Ti 2 Ni and Ni 3 Ti phases were found in the microstructure of the printed parts. Based on the DSC analysis, the transformation temperatures of austenitic NiTi to martensite and vice versa were determined. [Display omitted] • Spherical Ni–Ti composite powder has been synthesized from elemental powders by radio frequency plasma spheroidization. • The powder feeding rate and carrier gas flow rate affects the spheroidization efficiency and powder composition. • The synthesized slightly Ti-rich powder has been adopted for selective laser melting densification. • The multiple-phase microstructure containing NiTi, Ti 2 Ni and Ni 3 Ti in the SLMed sample is characterized. [ABSTRACT FROM AUTHOR]

The effect of Fe nanoparticles with mass fraction of 0-7 wt% on the microstructure and soft magnetic properties of the Fe-6.5 wt%Si soft magnetic composites (SMCs) was investigated. The results show that the pores between Fe-6.5 wt%Si powders can be effectively filled by Fe nanoparticles, thereby correspondingly increasing the density of the SMCs. At the same time, the magnetic permeability of the SMCs mixed with different mass fraction of Fe nanoparticles has improved significantly and exhibits good frequency stability compared with the absence of Fe nanoparticles. It also reveals that the addition of 1 wt% Fe nanoparticles can reduce the eddy current loss of the SMCs by decreasing its intra-particle eddy current loss. When the addition of Fe nanoparticles is 3 wt%, the SMCs exhibits good magnetic properties with high magnetic permeability (increased by 24%) and relatively low core loss. Image 1 • The permeability of Fe-6.5Si SMCs increases obviously by adding Fe nanoparticles. • Introducing 1 wt% Fe nanoparticles can decrease eddy current loss of the SMCs. • SMCs with 3 wt% Fe nanoparticles exhibits high permeability and low core loss. [ABSTRACT FROM AUTHOR]