Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy was fabricated by laser directed energy deposition (LDED) using laser powers of 550–800 W and scanning speeds of 1100–1500 mm/min to investigate the effect of thermal input on amorphous-phase retention and thermal stability. X-ray diffraction showed that all as-built samples were predominantly amorphous within the investigated processing window. Differential scanning calorimetry revealed a significant transition in crystallization behavior with increasing thermal input. At 550 W, the crystallization exotherms remained in the range of 600–700 °C, comparable to those of the feedstock powder. In contrast, at 700–800 W, the low-temperature exotherm was suppressed, and a dominant high-temperature exotherm appeared at approximately 780–820 °C, with its intensity increasing as the effective cooling rate decreased. Transmission electron microscopy combined with EDS mapping demonstrated that higher thermal input promoted elemental segregation and the formation of a limited number of nanoscale crystalline phases. This behavior is attributed to process-induced compositional modulation resulting from partial crystallization and solute redistribution during deposition. The modified amorphous matrix exhibited enhanced thermal stability, which effectively suppressed crystallization during subsequent thermal cycles. The results indicate that, within an appropriate processing window, a moderate reduction in the effective cooling rate can improve the thermal stability of additively manufactured Fe-based amorphous alloys, thereby promoting the retention of a higher amorphous fraction under cyclic thermal conditions.

In this work, the effect of lattice structure on the corrosion behavior and passivation film properties of reinforced Al 0.5 Ti 3 Zr 0.5 Nb x Mo 0.2 (x = 0.5,0.8,1) high-entropy alloys are investigated. A single-phase BCC Al 0.5 Ti 3 Zr 0.5 Nb x Mo 0.2 (x = 0.5, 0.8, 1) high-entropy alloys, exhibiting good corrosion resistance, are synthesized using vacuum arc melting. Nb improves the corrosion resistance of high-entropy alloys in two main ways. On the one hand, the alloys show preferential corrosion at the {011} crystalline planes. Increasing Nb content reduced the {011} crystalline plane spacing, enhancing the corrosion resistance of Al 0.5 Ti 3 Zr 0.5 NbMo 0.2 . On the other hand, during the corrosion process, Nb, which has a large atomic radius and strong oxygenophilicity, interacts with each metal element, contributing to the uphill diffusion of Al/Ti and the downhill diffusion of O. The low-valent oxides form first continuously react with the inward-diffusing O to form high-valent oxides. This results in the formation of a layered passivation film with high breakdown potential and high stability. This work provides a basis for designing chemically robust alloys for extreme environments.

In this paper, the effect of ultrasonic field on the catalytic performance of Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy powder on Direct Yellow 120 (DR 120) and Direct Red 31(DR 31) mixed dyes was studied. The ultrasonic power has a significant effect on the catalytic degradation of mixed dyes, and the degradation efficiency of mixed dyes begins to increase only when the ultrasonic power is increased to 100 W. At 150 W, the electron work function (EWF) of the catalyst decreases from the original 6.05 eV-5.34 eV, at which time the electrons on the alloy surface are completely released and the degradation efficiency of mixed dyes reaches the maximum value. At the same time, the precipitation of (Fe, Cr)23C6 and Cr23C6 phases during the reaction facilitated the conversion of Cr0 to Cr3+, accelerated the destruction of C=O and O-H bonds on the surface of MGs, resulting in the increase of Fe2+ content on the surface of MGs, thus promoting the formation of center dot OH. This study provides a promising method for the catalytic degradation of azo dyes.

Amorphous alloy is a popular choice for wastewater treatment because of its high active sites and high catalytic performance. It is different from the previous situation that the degradation performance of amorphous materials decreases first and then increases after crystallization. The degradation efficiency of Direct Yellow GR dye (DYGR) by Electro-Fenton (E-F) is gradually increases as the amorphous content of Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy powder (MGs) is reduced in this work. The in-situ precipitation of (Fe, Cr)23(C, B)6 and Fe7C3 nanocrystals was discovered to decrease the electron work function (EWF) of the alloy powder, thus decreasing the amount of work needed to escape electrons and enhancing the electrocatalytic performance of the material. At the same time, the precipitation of (Fe, Cr)23(C, B)6 nanocrystals changed the chemical composition of the surface of MGs. After annealing, the Fe2+ concentration was higher than before regression, and the chemical potential energy between Fe2+ and Fe3+ was greater, thus facilitating the formation of ∙OH. This research offers novel perspectives on the utilization of nanocrystals in the management of amorphous alloy wastewater.

In this study, the amorphous-nanocrystalline dual-phase structure Fe78Si13B9 alloy ribbons (FeSiB) were prepared by single roll stripping method. The degradation efficiency of FeSiB for direct yellow dyes (DYGR) was 83

The BCC high entropy alloy (HEA) has always been considered a promising material for high temperatures, and a novel BCC HEA was developed in this study. The precipitation of a second HCP phase in the grain during the warming process is responsible for the alloy's characteristic high temperature strength. The dynamic modulus of the alloy increased continuously above 550°C, while its internal friction peak exhibited the typical signature of a grain boundary peak. Annealing at 800°C for 3 hours has the potential to slightly enhance ductility and reduce room temperature compression strength to a limited extent. It is believed that the initial decrease and subsequent increase in dynamic modulus can be attributed to the combination of second phase precipitation and thermal relaxation. The TEM and fracture SEM analysis of heat-treated specimens revealed that the modification of high temperature hardening and ductility was attributed to the second phase, which impedes the dislocation's movement.

In this work, we investigated the thermal stability, oxidation resistance and high temperature mechanical properties of refractory high entropy alloys Ti75Al10V5Cr5Nb5, Ti67Al12V7Cr7Nb7 and Ti55Al15V10Cr10Nb10(at.%). It is found that the second phase would be precipitated and occurs order-disorder transformation in refractory high entropy alloys at high temperature. The HCP phase produced orderly B2 phase and decreased the orderly B2 phase precipitation with the increasement of temperature in Ti67Al12V7Cr7Nb7 and Ti55Al15V10Cr10Nb10. According to the oxidation kinetics of high entropy alloys after 100h oxidation at 800 degrees C, the oxidation index factor n is between 1.1 and 1.2 and the degree of oxidation is between oxidized and inoxidized, all three refractory high entropy alloys formed oxides with rutile structure, the Ti67Al12V7Cr7Nb7 being less oxidation resistant due to the generation of Nb2O5 which is less stable at high temperature. Ti67Al12V7Cr7Nb7 has a yield strength of 522 MPa with 50% elongation at 650 degrees C. Ti75Al10V5Cr5Nb5 and Ti67Al12V7Cr7Nb7 have lower strength but 150% deformation without fracture when stretched at 750 degrees C. The multi-component intermetallic compound nanoparticles formed by the second phase and ordered phase together in the refractory high entropy alloys have an Orowan strengthening effect, to improve the mechanical properties at high temperature since it effectively prevents dislocation movement and stores dislocations.

采用粉末注射成形工艺制备钡钨阴极多孔钨基体,定量表征钨粉的粉末粒度和粒形,重点研究粉末粒形对多孔钨基体孔隙特性的影响.通过对比粉末的球形度、形状因子、圆润度、粗糙度、赘生物指数和凹度等特征参数,发现球形钨粉比商品还原钨粉和窄粒度钨粉具有更好的球形度、表面光滑度以及分散度.当粉末粒度相差不多时,通过改善钨粉的颗粒形状,粉末分散度得到提高,SW粉末经注射成形得到的多孔钨基体(PSW)的孔隙结构均匀性最佳,其平均孔隙度、平均开孔孔隙度、平均孔径和孔隙总容积分别为24.0%、23.9%、1.17 μm、0.0206 mL/g.

Chemical short-range order (CSRO) is widely reported and it's certainly related to high entropy alloys (HEAs)'s mechanical properties in many different correlative researches. B2 structure ordering is usually thought to improve alloy's structural stability and strength while sacrificing the plasticity significantly. In this work, we established a B2 ordered model by the special quasi-random structure method which considering the local atomic environment (to simulate the real situation in HEAs). Depending on this model and first principles, the elements' occupancy and the B2 structure ordering are considered to explore their influence on the mechanical properties of AlTiCrVNb HEAs. The B2-type partially ordered configuration was applied to non-iso atomic ratio alloys to investigate the different influence on alloys' mechanical properties due to the changing content of Ti or Cr and the results were verified by experiment.

In this work, we designed and successfully prepared new lightweight refractory high entropy alloys (HEAs) Ti75Al10V5Cr5Nb5, Ti67Al12V7Cr7Nb7 and Ti55Al15V10Cr10Nb10 with BCC/B2 structure. It was found that TiAlVCrNb high-entropy alloy plasticity is mainly generated by dislocation aggregation at grain boundaries and intracrystalline, and strength is provided by solid solution strengthening and BCC/B2 structure. The results show that the Ti75Al10V5Cr5Nb5 high-entropy alloy have a great room temperature compressive plasticity of > 50% and a tensile elongation after break of 6% with the preferential orientation (200) and more dislocations, resulting in good plasticity. The Ti55Al15V10Cr10Nb10 high-entropy alloy has a room temperature compressive a yield strength of 1465 MPa and a compressive strength of 1835 MPa, as the Ti content decreases, the effect of solid solution strengthening will decrease, but the B2 structure content increases so that the mixed structure formed by BCC/B2 structure provides more strengthening. The light refractory high entropy alloy can control the Ti content to change the BCC/B2 structure content to obtain higher strength and plasticity.(c) 2023 Elsevier B.V. All rights reserved.

By employing high-throughput first-principles calculations, the segregation capacity of fifteen widely used metallic alloying elements (viz., Be, Mn, Co, Cr, Ni, Al, Mo, W, Mg, Ta, Nb, Sb, Sn, Zr, and Bi) at P3 grain boundary in low alloy ferritic steel, as well as their impact on grain boundary stability, interfacial separation work, and other properties, were systematically investigated. The findings reveal that, for alloying atoms Sb, Sn, Bi, Nb, and Zr, whose size is notably larger than that of the matrix Fe atoms, the effect of strain energy minimization in segregation is comparable to that of chemical energy minimization. Furthermore, the impact of strain energy minimization is closely related to the volume of the alloying atoms both at the solid solution sites in the crystal and at the segregation sites at the grain boundary. Thus, the segregation of large alloy atoms on the grain boundaries can be predicted by atomic volume of each segregation site, which can provide valuable insights for the development of new alloys and for grain boundary engineering.(c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Laser 3D printing, also known as laser additive manufacturing (LAM), is favored for its ability to form bulk metallic glass (BMG) and its composite materials (BMGcs) with freeform geometries. In this work, two different kinds of Fe41Co7Cr15Mo14C15B6Y2 amorphous coatings (A and B) were prepared by using LAM technology under air- and water-cooled conditions, respectively; meanwhile, to reduce the cracks generated due to the residual thermal stresses, coating C obtained by air-sweep annealing of B with a low energy-density laser. The morphology and amorphous content and microstructure of the coatings were investigated, the results show many cracks in coating B deposited under water-cooled conditions, and its microstructure shows an amorphous-crystal-nanocrystalline mixed structure. Cracking was suppressed in coating C, obtained by air-sweep annealing based on coating B, but the amorphous content was reduced from 32.6 to 13.4%. And the hardness and corrosion resistance of the coating will increase with the increase in the amorphous content. Finally, the internal friction behavior of a BMGcs was prepared on the basis of the process of sample C is compared with that of as-cast amorphous alloys. The results show that the low temperature internal friction behavior of BMGcs is affected by the defects produced during printing, and the high temperature internal friction behavior is affected by the precipitated hard phase.

Metallic glasses have recently attracted great attention in terms of degrading dyes and other organic pollutants as an environmentally friendly material for wastewater remediation.Herein,we report a new type of amorphous catalyst Fe41Co7Cr15Mo14C15B6Y2 hollow balls.Results demonstrate that the catalyst can still completely decolorize the 20 mg/L methylene blue(MB)solution after reused for 50 times under conditions of pH=5,catalyst content 0.5 g/L,and temperature 80℃.The catalyst is easily broken during degradation,so the inner surface also provides additional active sites.The Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy hollow balls were characterized by energy dispersive X-ray specroscopy(EDS),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS),respectively.The elements in the catalytic system have a synergistic catalytic effect.Redox cycle Fe2+/Fe3+,Co2+/Co3+and Mo4+/Mo6+promote mutual conversion and accelerate the catalytic process of their reaction with H2O2,forming a self-stable redox cycle process.Among them,Fe2+promotes the conversion of Co3+to Co2+,and Mo4+promotes the conversion of Fe3+to Fe2+,mainly Fe2+and Co2+react with H2O2 to generate·OH.Mo and Cr elements form MoO2 and Cr2O3 plasma compounds on the surface,which act as a protective film to make the catalyst more stable and be repeated used more frequently.

In the current work, internal friction and mechanical properties of a Fe41Co7Cr15Mo14-xC15B6Y2Six (x = 0.5, 1, 1.5 and 2 at.%) bulk metallic glasses (BMGs) was investigated. Investigations demonstrated that the Si content could play an important effect on the mechanical properties of Fe-based bulk metallic glasses. The influence of Si on mechanical properties may be related to the structural heterogeneity in the metallic glasses. The quasi-point defects theory was used to describe the structural heterogeneity. Quasi-point defect concentration represents the degree of structural heterogeneity of amorphous alloys. The addition of Si reduces the quasi-point defect concentration in the amorphous samples, and the low quasi-point defect concentration increases the modulus, hardness and fracture strength of the samples. The quasi-point defect concentration of the sample with 1 at.% Si content is the lowest. Results shows that the mechanical properties of amorphous alloy can be improved by adding appropriate an amount of Si.

A low density refractory high entropy alloy of composition TiCrVNb0.5Al0.5 was prepared by vacuum arc melting. Due to the formation of a single-phase BCC structure with uniform element distribution and a gradient passive film with a high concentration of passivating elements, the TiCrVNb0.5Al0.5 high entropy alloy (HEA) exhibits low corrosion current density (10(-7) similar to 10(-8) A cm(-2)), high breakdown potential (1.8-1.9 V-SCE) and excellent repassivation ability in 3.5 wt% NaCl and 1M HCl solutions. The properties were compared with HEAs, bulk metallic glasses (BMGs) and traditional alloys reported in literatures. The results show that TiCrVNb0.5Al0.5 possesses the most outstanding corrosion resistance in chloride environment. (C) 2020 Elsevier B.V. All rights reserved.

通过对金刚石表面化学镀Ni对金刚石颗粒镀覆金属层进行表面改性.采用X射线衍射仪(XRD)对Fe基非晶合金进行物相分析,利用差示扫描量热仪(DSC)测试Fe基非晶粉的特征温度点,采用扫描电子显微镜(SEM)观察界面结合情况和界面产物微观形貌,用能谱仪(EDS)进行物质元素分析,采用激光热导仪(LFA447)对复合材料进行热扩散系数测试.结果表明:充分利用Fe基非晶合金相转变过程中的原位自放热,提升Al液的流动性,增强了金刚石/Al复合材料的界面结合能力.Fe基非晶合金相转变后多组元晶体的形核和长大,提高了复合材料界面热阻,降低了金刚石/Al复合材料的峰值导热性能.Fe基非晶的引入提高了金刚石/Al复合材料的导热稳定性,在测试温度范围内,导热稳定性提高10.3％.引入过量的Fe基非晶合金或过长的制备时间会引起金刚石颗粒发生碳化.

The Fe41Co7Cr15Mo14C15B6Y2 amorphous alloy powder was prepared by gas atomization. It was interesting that rhodamine B can be completely degraded within only 6 min by 1 g/L Fe41Co7Cr15Mo14C15B6Y2 and 3 mM H2O2 at pH 5.0 at 313 K. This result can be repeated at least 30 times. It is worth mentioning that the catalyst surface spontaneously formed a double passivation film during the degradation process. The passivation film composed of Cr2O3 and Cr(OH)3 is located in the outer layer, while the passivation film composed of MoO2 and MoO3 is located in the inner layer. This double passivation film regulates the contact of ions on the catalyst surface with the solution, which makes the catalyst have a stable catalytic efficiency in the reaction. The findings have important implications in developing Fe-based amorphous alloys for functional application materials in the field of wastewater treatment.

The transformation rule of beta(2)-phase and its effect on the mechanical properties at room temperature in the cast TiAl alloy were studied. The results show that the toughness of the cast Ti-Al-Nb-Cr-Mo-B alloy is not decreased when the holding time is 2 h, but the strength is increased from 1200 MPa to 1500 MPa. In the process of heat preservation, a decomposes into gamma +beta phase, and then in the process of cooling, the disordered beta phase transforms into ordered beta(2) phase. It is demonstrated that beta(2) phase is a hard brittle phase, and a small amount of beta(2) phase can promote the strength of the alloy.

Low-energy synthesis has always been a challenge for Sialon. Meanwhile, sialon with controllable morphology is difficult to synthesize at a lower temperature. In this paper, silicon powder, diamond powder, pure aluminium, Al-12Si alloy and Al2O3 powders are selected as raw materials. Temperature design scheme is 1100 degrees C for 3 h and insulation at 1100 degrees C for 2 h + 1200 degrees C for 1 h. Sialon nanowires, Sialon nanoparticles and Sialon nanorods are synthesized at the diamond interface, respectively. It is worth noting that Sialon nanotubes were synthesized at the diamond interface during the experiment. The internal structure of the sample was analyzed by transmission electron microscopy (TEM). Microstructure of sample fracture is observed by scanning electron microscopy (SEM). The phase analysis and component analysis of the samples were carried out by X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). It is proved that the diamond interface first generated nano-SiO2. It is found that there are two formation mechanisms of SiO2 on diamond surface, one is formed by oxidation of Si powder, the other is formed by chemical reaction of Si powders and Al2O3 powders. Through the study of microstructure, the densification process of nano-SiO2-Al2O3 composite layer is discussed, and the possible nucleation and growth mechanism of four kinds of nanostructures are analyzed. The discovery of controllable Sialon nanostructure through low-energy synthesis of diamond interface has potential prospects in functionalized diamond composites. (C) 2020 Elsevier B.V. All rights reserved.

从“材料分析测试技术”对材料类专业学生重要性出发,结合“材料分析测试技术”课程特点,介绍了多媒体课件设计构思.采用主框架软件Authorware、动画软件Flash MX、图形软件Photoshop、音频软件Premiere等制作了该课程的多媒体课件,并论述了相关制作技术.将多媒体课件运用于教学中,特别采用了模拟实验环境的动画操作演示形式和视频演示形式,取得了良好的教学效果.