[en] Highlights: • Magnetic functional fluid based on amorphous particles is prepared. • Fe_7_3_._5Nb_3Cu_1Si_1_3_._5B_9 particles are still amorphous after being milled for 48 h. • We investigate hyperthermia effects of three types of magnetic functional fluids. • Fe_7_3_._5Nb_3Cu_1Si_1_3_._5B_9 MR fluid exhibits more significant heating effect. - Abstract: An experimental study conducted on the preparation and hyperthermia effect of magnetic functional fluids based on Fe_7_3_._5Nb_3Cu_1Si_1_3_._5B_9 amorphous particles, CoFe_2O_4 nanoparticles and Fe_3O_4 nanoparticles dispersed in water is presented. Scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and vibrating sample magnetometer methods have been used to characterize the morphology, structure and magnetic property of the amorphous particles. It is disclosed that the Fe_7_3_._5Nb_3Cu_1Si_1_3_._5B_9 particles are still amorphous after being milled for 48 h. Moreover, the saturation magnetization of metallic glass particles is approximately 75% and 50% larger than that of CoFe_2O_4 nanoparticles and Fe_3O_4 nanoparticles, respectively. The hyperthermia experiment results show that when alternating electrical current is 150 A, the temperature of the functional fluids based on amorphous particles could rise to 33 °C in 1500 s. When the current is 300 A, the final stable temperature could reach to 60 °C. This study demonstrates that the Fe_7_3_._5Nb_3Cu_1Si_1_3_._5B_9 magnetic functional fluids may have potential on biomedical applications

[en] Prepeaks are observed in the x-ray diffraction patterns of molten Fe₃Si and FeSi alloys and the mechanism of their microstructures is discussed. The distance in real space corresponding to the prepeak positions resembles that of the Si-Si distances in the D0₃ type crystal of Fe₃Si within a deviation of 2.4%. Furthermore, by the reverse Monte Carlo (RMC) simulation, the prepeak is only found in the partial structure S_SiSi(Q) for molten Fe₃Si alloy, while in molten FeSi alloy prepeaks are found in both S_SiSi(Q) and S_FeFe(Q) with similar height. The Gaussian distribution is found in the partial coordination number distribution of Fe atoms around a Si atom in the two alloys. The dominant 7-coordination in molten FeSi alloy suggests that Fe₇Si and FeSi₇ type clusters are kept in the molten state from FeSi crystal. Si-Si coherent packing should be responsible for the medium range order (MRO) of molten Fe₃Si while Fe-Fe and Si-Si coherent packing for that of molten FeSi

[en] Based on the analysis of the X-ray diffraction data of liquid Al and Sn, temperature-induced structural transformations are found for liquid Al in the range of 1050-1250 degree C and for liquid Sn near 800 and 1200 degree C. The nearest neighbor distance r₁ of Al and Sn decreases with the increase of temperature. The structure of liquid Sn is similar to α-Sn on the short-range order length scale. The physical meaning of the correlation radius r_c is discussed

[en] By applying ab initio molecular dynamics simulation to liquid Cu₆Sn₅ alloy, the hetero-coordination tendency is discovered by Bathia-Thornton partial correlation functions and a chemical short-range parameter. However the local structural environment of Sn in l-Cu₆Sn₅ alloy resembles that of liquid Sn by Voronoi analysis. A new feature, i.e. a subpeak in between the first and second peaks, is discovered by the present method which implies that topologically disordered β-Sn-type structural units may exist in l-Cu₆Sn₅ alloy. The local density states of electrons show that both Cu-Sn and Sn-Sn bonding exist in l-Cu₆Sn₅ alloy. This work suggests that chemical short-range order between unlike atoms and self-coordination between Sn atoms coexists in l-Cu₆Sn₅ alloy.

[en] A composite was prepared at room temperature from nitrogen-doped reduced graphene oxide (N-rGO) and melamine via π-interaction. An ultra-sensitive electrochemical sensor for the determination of trace levels of bisphenol A (BPA) was obtained by coating a glassy carbon electrode (GCE) with the composite. The structure and morphology of composite were characterized by FTIR, Raman, XRD, XPS, SEM and TEM. Because of the synergetic effects of N-rGO and melamine, the modified GCE displays considerably enhanced sensitivity to BPA. The voltammetric response, typically measured at a peak of 0.48 V (vs. SCE) is linear in the 0.05 to 20 μM BPA concentration range, and the detection limit is 0.8 nM (at S/N = 3). The sensor is reproducible, stable and selective. It was applied to analyze baby bottles, drinking cups, mineral water bottles and shopping receipts that were spiked with BPA, and the recoveries reached 99.1–101.4%. .

[en] Highlights: • A novel method aiming at recycling Fe–rich Al–Si alloys by introducing them into Mg melt to separate Al and Fe is proposed. • β–Al₅SiFe phase in Al–Si–Fe alloys can be designed evolving to Al–poor Fe₃Al_0.7Si_0.3 by controlling the melting process. • A separation layer rich of Fe can form at bottom while Al is released to the upper melt. The recycling of high Fe–contained Al–Si alloys is a green industry and how to separate Al and Fe is the key point therein. An efficient technique using Mg melt to separate Al and Fe is proposed in this study. By introducing Al–14 wt% Si–4 wt% Fe alloy into Mg melt and adjusting melting, holding and cooling parameters, the evolution behavior and separation performance of Fe–rich intermetallics were investigated. A separation layer with Fe–rich particles was obtained at the bottom of the cooled ingot. A meta–stable phase Fe₃Al_0.7Si_0.3 was detected, which only exists above 699 °C confirmed by a thermodynamic calculation. Making β–Al₅SiFe phase from the initial Al–14 wt% Si–4 wt% Fe alloy transform to Fe₃Al_0.7Si_0.3 in Mg melt is beneficial to achieve higher separation efficiency since the Fe₃Al_0.7Si_0.3 phase is Al–poor, indicating that quantities of Al are released to the Mg matrix. Holding at 750 °C for 30 min followed by a further holding at 650 °C for 30 min is regarded most proper in this study. This work may be referred by relative study on the evolution of intermetallics by introducing one matrix alloy into another melt.

[en] Highlights: • A simple liquid Ga assisted-alloying/dealloying strategy to fabricate nanoporous Ag. • The thickness of alloy layer/nanoporous Ag varies with the mass loading of Ga. • The bimodal wire-like and unimodal bulk-like nanoporous Ag is obtained. • The substrate-supported nanoporous Ag exhibits excellent mechanical properties. -- Abstract: Nanoporous metals show great potentials in various applications including catalysis, sensing, actuation and supercapacitors. The liquid Ga-assisted alloying/dealloying strategy is a feasible and scalable way to fabricate substrate-supported nanoporous metals. However, the influence of intrinsic alloying mode and mechanism on the formation and modulation of nanoporous structure has not been thoroughly explored before. In this work, after painting liquid Ga on Ag foil, both the bulk-like Ag₃Ga (in the Ag-rich zone) and wire-like Ag₃Ga (in the liquid Ga-rich zone) form owing to the interdiffusion of Ag and Ga atoms. Correspondingly, the bimodal wire-like and unimodal bulk-like nanoporous Ag is obtained because of the structure inheritance during dealloying. In addition, the thickness of alloy layer (nanoporous layer) versus mass loading of liquid Ga follows a good linear relationship. The in-situ X-ray diffraction of dealloying from Ag₃Ga to nanoporous Ag illustrates no other intermetallic phase appears and the dealloying process can be described by the dissolution-surface diffusion model. More importantly, the substrate-supported nanoporous Ag exhibits excellent mechanical properties which are of great importance to the future applications of nanoporous metals.

[en] The structure of liquid Al₈₀Si₁₅P₅ alloy was investigated by ab initio molecular dynamics simulation in order to understand the mechanism of modification of Si primary phases by P in Al-Si alloys. It is found that the chemical environment around P atoms is crucial to provide insight into the structure of liquid Al₈₀Si₁₅P₅ alloy. The P-centered Al₆P structural units exist at 1373 K but are slightly distorted at 2873 K. One P atom usually has other P atoms at the next neighborhood bridged by Al atoms, and also tends to exclude Si atoms from its first coordination shell. Based on the structure information, some aspects related with the modification mechanism are discussed.

[en] Local structure inheritance signatures were observed during the alloying process of the Ag₅₀Sn₅₀ melt, using high-temperature X-ray diffraction and ab initio molecular dynamics simulations. The coordination number N_m around Ag atom is similar in the alloy and in pure Ag melts (N_m ∼ 10), while, during the alloying process, the local structure around Sn atoms rearranges. Sn-Sn covalent bonds were substituted by Ag-Sn chemical bonds, and the total coordination number around Sn increases by about 70% as compared with those in the pure Sn melt. Changes in the electronic structure of the alloy have been studied by Ag and Sn K-edge X-ray absorption spectroscopy, as well as by calculations of the partial density of states. We propose that a leading mechanism for local structure inheritance in Ag₅₀Sn₅₀ is due to s-p dehybridization of Sn and to the interplay between Sn-s and Ag-d electrons

[en] The resistivity behavior of undercooled liquid Cu-Ni and Cu-Co alloys had been studied in the contactless method, to probe the structure transition in undercooled melts during the cooling process. Over the entire concentration range, linear behavior of resistivity with temperature was obtained in liquid and undercooled liquid Cu-Ni system. It implied that the formation of icosahedral order might not influence the electron scattering in undercooled liquid Cu-Ni alloys. Similar results were obtained in Cu-Co system in the vicinity of liquidus temperature. A turning point was obvious in temperature coefficient of resistivity for undercooled liquid Cu-Co alloys around the bimodal line, which was interpreted to be responsible for metastable liquid-liquid phase separation. During liquid phase separation process, resistivity decreased and the temperature coefficient of resistivity was larger than that of homogeneous melts. In combination with transmission electron microscopy and scanning electron microscope studies on the as-solidified microstructure, this was interpreted as the formation of egg-type structure and concentration change in Cu-rich and Co-rich phases. The mechanism controlling the separation and droplets motion was also discussed in undercooled liquid Cu-Co system.