Fine particles with carbon coating are generally necessary to achieve acceptable electrochemical performance for LiFePO4 (LFP) due to the poor intrinsic electric and ionic conductivities. In this work, the synergy of polyethylene glycol (PEG) was investigated as both grinding aid and carbon source to modify LFP toward high performance. The yielded graphite coating has a limited thickness of 8 nm, regardless of the concentration and molecular weight of PEG, while the extra concentration results in amorphous carbon dispersed among particles. A higher PEG concentration produces finer LFP particles but less active materials, while the semi-solid PEG shows the best grinding effect toward a reversible capacity close to the theoretical value. These results could be well addressed based on polymer conformations, and this work paves a more efficient way to develop high-performance LFP.

Compared with conventional crystalline materials, amorphous alloys exhibit superior radiation resistance which attributed to their long-range disordered structure, abundant free volume, and absence of defects such as dislocations. Consequently, they are considered promising candidates for plasma-facing materials in fusion reactors. However, the damage mechanisms of amorphous alloys under H ions irradiation remain unclear. In this study, both amorphous and crystalline Zr63.5Cu23Al9Fe4.5 alloys were irradiated at room temperature with 0.9 MeV H-2(+) ions at the fluence of 5 x 10(17) ions/cm(2). The peak displacement damage reached 3.2 dpa, with a peak hydrogen concentration of similar to 36.8 %. Using XRD, TEM, EDS, Nanoindentation, this study investigated the microstructural evolution (including phase structure and bubble behavior) and mechanical property changes of Zr63.5Cu23Al9Fe4.5 amorphous and crystalline alloys under H-2(+) ions irradiation. The results indicated that the irradiated amorphous alloy maintained its disordered structure, while the crystalline alloy underwent partial amorphization, transforming into an amorphous-crystalline composite after irradiation. Notably, the irradiation-induced amorphous regions in crystalline alloy retained inhomogeneous elemental distribution similar to that observed prior to irradiation. After irradiation, bubbles were observed in both materials. The amorphous and crystalline alloys exhibited bubble layer depths of 6.4 mu m and 6.1 mu m, respectively, with average bubble sizes of 6.09 nm and 4.19 nm, and bubble densities of 1.8/nm(2) and 2.04/nm(2). In contrast to the homogeneous bubble distribution in the amorphous alloy, bubbles in the crystalline alloy tended to aggregate along the grain and phase boundaries. Nanoindentation results revealed irradiation-induced changes in hardness and serrated flow behavior for amorphous and crystalline alloys. Importantly, the amorphous alloy exhibited clear post-irradiation softening, which was attributed to the generation of excessive free volume under irradiation. In the crystalline alloy, softening was mainly related to grain boundary annihilation. Additionally, serrated flow behavior was observed in both types of irradiated alloys. In the irradiated amorphous alloys, serrated flow behavior was weaker and plastic deformation was more homogeneous. Due to crystalline alloy formed amorphous-crystalline composite structure, the interfaces effectively hindered shear band propagation and suppressed the formation of mature shear bands, with virtually no pop-in events exceeding 2 nm in size being detected.

In this paper, high-energy Ne ions were used to irradiate Zr 63.5 Cu 23 Al 9 Fe 4.5 metallic glass (MG) and crystalline W to investigate their difference in mechanical response after irradiation. The results showed that with the irradiation dose increased, the tensile micro-strain increased, nano-hardness increased from 7.11 GPa to 7.90 GPa and 8.62 GPa, Young’s modulus increased, and H 3 / E 2 increased which indicating that the plastic deformability decreased in crystalline W. Under the same irradiation conditions, the Zr 63.5 Cu 23 Al 9 Fe 4.5 MG still maintained the amorphous structure and became more disordered despite the longer range and stronger displacement damage of Ne ions in Zr 63.5 Cu 23 Al 9 Fe 4.5 MG than in crystalline W. Unlike the irradiation hardening and embrittlement behavior of crystalline W, Zr 63.5 Cu 23 Al 9 Fe 4.5 MG showed the gradual decrease in hardness from 6.02 GPa to 5.89 GPa and 5.50 GPa, the decrease in modulus and the increase in plastic deformability with the increasing dose. Possibly, the irradiation softening and toughening phenomenon of Zr 63.5 Cu 23 Al 9 Fe 4.5 MG could provide new ideas for the design of nuclear materials.

In order to study the physical mechanism of the effect of complex fusion irradiation environment on Zr-based amorphous alloys, simultaneous irradiation with Fe and He ions was performed on Zr63.5Cu23Al9Fe4.5 amorphous and crystalline alloys at room temperature. Single Fe ions irradiation and single He ions irradiation were used for comparison to investigate the influence of synergistic effects as well as intrinsic structural differences on irradiation-induced microstructural evolution and mechanical properties. It was been found that the irradiated amorphous alloys maintained its amorphous structure without nanocrystallization or elemental segregation. However, the irradiated region of the crystalline alloys experienced full amorphization, forming amorphous structure with bright contrast (Al-rich) and dark contrast (Cu-rich or Fe-rich). Under single He ions irradiation and simultaneous Fe+He ions irradiation conditions, He bubbles generated in both amorphous and crystalline alloys, where He bubbles in amorphous alloys distributed homogeneously, while the Cu-rich region of crystalline alloys exhibited larger sizes of He bubbles. Compared to single He ions irradiation, the size of He bubbles was larger, the atomic arrangement was more disordered (for amorphous alloys) and the element distribution was more homogeneous (for crystalline alloys) after simultaneous irradiation. Compared to single Fe ions irradiation, simultaneous irradiation induced slightly greater swelling. After irradiation, obvious softening was observed in both alloys, and the hardness of amorphous alloys was as follows: unirradiated > single He ions irradiation approximate to single Fe ions irradiation approximate to simultaneous Fe+He ions irradiation, while that of crystalline alloys was as follows: unirradiated > single He ions irradiation > single Fe ions irradiation approximate to simultaneous Fe+He ions irradiation. The serrated flow behavior of amorphous alloys weakened and the deformation was more homogeneous. As a result of irradiation-induced amorphization, serrated flow phenomenon also occurred in crystalline alloys, however, this type of inhomogeneous amorphous structure showed much weaker serrated flow behavior than the homogeneous amorphous structure. This study provides a deeper understanding of the irradiation damage mechanism of Zr-based amorphous alloys in complex irradiation environments.

The waste blades of single crystal superalloys have not been formally applied on a large scale, resulting in serious waste. This study proposes to treat the waste blades through ultrasonic alkali cleaning combined with electron beam smelting (EBS). The theoretical model is proposed to study the elements volatilization, which provides a reference for controlling the alloy composition. After EBS, the secondary dendrite spacing and the size of gamma ' phases of DD5 alloy is significantly reduced. The EBS technology can effectively reduce the element segregation in superalloys, especially W and Mo elements. The purity of DD5 revert alloy after EBS is consistent with or even exceeds that of DD5 virgin alloy. Especially for the removal of ceramic shell and core materials in the waste blades, EBS has a new technological advantage. Under the combined action of Marangoni effect and buoyancy, the inclusions floating to the melt surface can not only be directly decomposed by the bombardment of the electron beam, but also can be dissolved under the condition of local melt superheating.

A new sort of nanoporous palladium has been synthesised by electrochemical dealloying icosahedral Al72Pd20Mn8 quasicrystal. A nanoporous cell-like pattern is formed in the dealloyed samples, with a mean pole size of 8 nm and a cell wall thickness of similar to 5 nm. The quasicrystal grains decompose into randomly orientated FCC Pd(Al) nanocrystals in the initial stage of dealloying, which assumes a prior mechanism accounting for the final microstructure size. The nanoporous palladium exhibits evident electrocatalytic activity towards the oxidation of ethanol and methanol in alkaline environment, and demonstrates the possible application as a cathode material in Li-O-2 batteries.

为了连接W和CLF-1 RAFM钢,设计出由低活化元素组成的Fe-B-Si、Fe-B-Si-Sn、Fe-B-Si-Cr-(Sn)、Fe-B-Si-P-(Cr,Sn)、Fe-B-Si-Mn-(Ga,Sn)和Fe-B-Si-(Cr,Mn,Ga,Ta,Sn)系列Fe基非晶钎料,结合熔体快淬技术制备出非晶合金箔带,并对W/CLF-1 RAFM钢接头微结构进行了对比研究.采用X-射线衍射仪对箔带样品与焊缝进行了相鉴定;通过差热分析测量了非晶箔带的熔化温度和液相线温度;利用光学金相和电子探针分析了焊缝组织形貌和元素分布.结果表明,利用 Fe-B-Si、Fe-B-Si-Cr 和 Fe-B-Si-Mn-Sn 非晶钎料可获得结构完整的W/CLF-1钢接头;前两种钎料得到的焊缝组织基体相为α-Fe固溶体,而含Mn钎料形成的焊缝基体为马氏体组织;在高温钎焊过程中,这些Fe基非晶钎料中的高B含量促使FeWB、FeW2B2和Fe3B型金属间化合物在焊缝中形成,并有效地阻止了W元素向低活化钢基体长程扩散.所设计的低活化Fe基非晶钎料可用于W和低活化钢的连接和接头性能研究.

为了解决CFC与CuCrZr合金的冶金连接问题,以二元合金Cu62Mn38(at.％)为基础成分,采用低熔点Ga作为主要合金化元素和微合金化元素Cr和Si,设计了系列固溶体钎料合金Cu62Mn37-xGaxCr0.5Si0.5(x=0～10,at.％).利用电弧熔炼、铜模吸铸和冷轧制备了 100μm厚的钎料箔带.采用Cu62Mn31Ga6Cr0.5Si0.5钎料在不同工艺条件下(875～900℃,保温 15～25min)制备了无氧铜和 CuCrZr 合金钎焊接头.通过热分析和 X-射线衍射分析了钎料熔化行为和相组成;采用光学显微镜、扫描电镜、电子探针和力学性能拉伸机对接头的组织形貌、成分分布和力学性能进行了分析.结果表明,在 880℃/保温 25min钎焊工艺下可获得无缺陷CFC/CuCrZr接头结构,焊缝的Cu固溶体基体内有少量不连续分布的粒状纳米Cr3Si析出相;在室温抗拉试验中,此接头的抗拉强度为215MPa,断后延伸率 40％,断裂模式为韧性断裂.该钎料和焊接工艺已应用于 HL-2M 偏滤器制造中碳纤维复合材料和CuCrZr合金的连接加工.

Metal oxide anode materials based on conversion reaction usually deliver a capacity much higher than that of commercial graphite anodes in lithium-ion batteries (LIBs), and the porous forms of the materials can effectively alleviate volume change associated with (de)lithiation. In this work, tetragonal γ-Fe2O3, which is a vacancy-ordered superstructure containing large vacancy clusters, is studied as the representative of intrinsic nanoporous metal oxide anode materials of LIBs. γ-Fe2O3 exhibits a reversible capacity higher than the theoretical value in initial cycles, but a steady capacity same as that of α-Fe2O3. In lithiation, γ-Fe2O3 first transforms irreversibly to an ordered rock salt Li1-xFe1+xO2 (LiTiO2 type), and the Li1-xFe1+xO2 is converted reversibly into Li2O and Fe0 upon further lithiation: γ-Fe2O3+Li→Li1-xFe1+xO2+Li ↔ Fe0+Li2O. The alternate stacking of dense tetrahedral layers and porous octahedral layers in γ-Fe2O3 enables the simultaneous formation of Li1-xFe1+xO2 phases with different Li contents in a single particle and triggers structure twinning, accounting for fast reaction and likely high capacity in initial cycles. The structural evolution disclosed in γ-Fe2O3 not only updates the understanding of conversion reactions of vacancy-ordered metal oxides, but also offers an innovative approach for the fabrication of twinning structures in metal oxides including cathode materials.

The microstructure and mechanical properties of tungsten (W) materials have strong influences on their thermal shock performance. In this work, a W-Y2O3 (0.14 wt% Y) alloy with bimodal grain structure was fabricated by swaging plus high energy rate forging of the hydrogen sintered compact. In tensile tests, the W alloy exhibits a high yield strength (& sigma;Y = 1400 MPa) and a plastic strain & epsilon; = 5.5% at room temperature, and extensive tensile strains exceeding 20% at 100-300 degrees C. Its thermal shock performance was assessed by applying cyclic edge localized mode-like long heat pulse for 100 times at room temperature with an electron beam equipment. Within the range 0.44-1.1 GW m � 2, the specimens are free of cracking, and the surface modifications change from shear step-like bulges to recrystallization with increasing absorption power density.

In this paper, the effects and the mechanisms of melt superheating treatment (MST) on a directionally solidified alloy were investigated. The mass loss rate of the superalloy becomes severe as the MST temperature rises. The chromium, tantalum, and hafnium are the primary evaporation elements during MST. As the MST temperature increases from 1500 to 1600 °C, the secondary dendrite arm spacing is reduced by 13.3%, and the average size of γ′ particles are reduced by 11.5% and 18.2% in the dendrite core and inter-dendritic area, respectively. The content of oxygen and nitrogen gradually reduces with the increase in the MST temperature. However, the sulfur content is not significantly affected by the MST temperature. The essential cause of γ′ phases transition is supposed to be the MST-induced changes in solute distribution and the decomposition of atomic clusters. In addition, the nitrides and Ti (N, C)-type carbides are continuously dispersed as the MST temperature increases, which promotes the removal of nitrogen impurities.

Atomic-scale structure properties of the epitaxial growth of the wurtzite ZnO film prepared on an a-plane sapphire (α-Al2O3) substrate have been investigated by using aberration-corrected transmission electron microscopy. The crystallographic orientation relationship of (0001)[1¯1¯20]ZnO//(112¯0)[0001]α-Al2O3 has been determined between the ZnO film and the α-Al2O3 substrate. Two types of oxygen-terminated a-plane α-Al2O3 substrate surfaces have been characterized, which leads to the formation of different heterointerface structures and ZnO domains with opposite lattice polarity. The coalescence of opposite polarity domains results in the appearance of inversion domain boundaries (IDBs) on prismatic planes, and kinks occur on basal planes during the propagation of IDBs within the film. Additionally, the structure of stacking mismatch boundaries in the film with threefold coordinated Zn and O atoms has been resolved. We believe that these findings can be helpful to advance the understanding of the complex propagation of planar defects (e.g., IDBs and stacking faults) in wurtzite films and the interface structure and polarity of wurtzite films on the a-plane sapphire substrate.

The recent attention on crystallization of undercooled glass-forming metallic liquids has been directing to the intriguing viscosity behaviors. The present study discloses that structural decomposition of the grown-out crystalline products plays a part in the crystal growth kinetics. In the supercooled liquid of Zr70Al12.5Fe17.5 metallic glass, the polymorphically crystallizing metastable T2-Zr6Al2Fe phase decomposes into T2 + T2 ' (space group:Amm2, a = 6.895 angstrom, b = 3.368 angstrom, c = 5.119 angstrom), and retards crystal growth. The structure decomposition also occurs in the solidified bulk alloys.

Electron beam melt superheating treatment (EBMST) is firstly proposed to prepare DZ125 alloy, which opens up a new way to further explore and improve the properties of superalloys. The effects of melt superheating treatment at ultra-high temperature on the composition, microstructure and purity of superalloy were studied. As the melt superheating power increases, the mass loss rate of the alloy increases gradually. A theoretical model for controlling alloy composition was established. The secondary dendrite spacing, the area fraction of the eutectic structure and the size of g0 phases decrease first and then increase with the increase of the melt superheating power. The sizes of g0 phases at dendritic core and interdendritic regions have the minimum values of 0.12 mm and 0.16 mm, respectively. As the melt superheating power increases, the segregation coefficients of Co and W increase first and then decrease, while that of Ti and Mo decrease first and then increase. The best purification effect is achieved at 14 kW, where the content of O and N are 1.8 ppmw and 1.2 ppmw, respectively. It means that 78% O and 80% N are removed from the raw materials.& COPY; 2023 Dalian university of technology. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/

The effects of impurity elements on the wettability and interfacial reaction between superalloy and ceramic shell were investigated by the sessile-drop method. The wetting angle decreases with the increase of impurity content and the decrease of holding temperature. In addition, the thickness of the interfacial reaction layer increases with the increase of impurity content and the decrease of holding temperature. The adsorption of interfacial active atoms such as O, N and S is the main driving force of the wettability diffusion, which can reduce the surface tension of the alloy melt and enhance the wettability of the solid-liquid interface.

This study indicates that the kinetic rate constants of oxidation weight gain and thickening both increase with the increasing content of O, N and S impurities. The oxide layer of the low-purity alloy is not tight and easy to peel off. Internal oxidation becomes more serious with the increase of oxygen solubility. The microscopic mechanism of how impurity atoms affect the oxidation diffusion process was explained, and the models of the oxide layer growth process for high-purity alloys and low-purity alloys were constructed, which provide a reference for the improvement of high-temperature oxidation performance of superalloys in the future.

The effects of He2+ irradiation on the structural stability and deformation behavior in Zr63.5Cu23Al9Fe4.5 and Fe80B13Si7 metallic glasses (MGs) were investigated by TEM and nano-indenter. He bubbles in Fe80B13Si7 MG distributed more narrowly along the depth direction, packed more densely and exhibited larger size. At 4 x 1017/ cm2 dose, Fe3B nanocrystals generated in Fe80B13Si7 MG caused by enhanced atomic diffusion due to increased excess free volume and larger compressive stress on atoms of bubbles gaps, while Zr63.5Cu23Al9Fe4.5 MG could maintain the amorphous structure. According to serrated flow phenomenon and bubbles distribution, the underlying mechanism of the transformation in deformation behavior of MGs with increasing He dose was analyzed as follows: localized inhomogeneous deformation in as-cast MGs, homogeneous deformation in the rejuvenated stage, localized inhomogeneous deformation in the stage where small bubbles act as weak pinning, homogeneous deformation in the stage where large bubbles act as strong pinning, localized fracture in the stage where bubbles collapse.

Compositions of typical binary and ternary bulk metallic glasses have previously been interpreted via a cluster formula approach, i.e., a good glass former is formulated by a nearest-neighbor cluster matched with one or three glue atoms, with a free electron number per unit formula approaching 24. In this study, a classical quaternary glass composition Zr55Cu30Al10Ni5, representative of bulk metallic glasses of complex chemistry and dual-glassy structure, is interpreted and optimized using a dual-cluster formula approach, i.e., a chemical formula representing two single-cluster formulas. First, the number of atoms in the dual-cluster formula is estimated from combinations of all possible single-cluster formulas of the major devitrification phase CuZr2, which ranges from 28 to 34. Second, the free electron number of each element is estimated using the Cu-Zr single-cluster formulas. Third, the reference composition Zr55Cu30Al10Ni5 is approximated into integer forms of 27 to 36 atoms and their free electron numbers are calculated using the assigned free electron numbers of the elements. The so-formulated compositions are examined for glass forming abilities via copper-mold arc melting. The atomic densities, the critical temperatures, the HV hardness, the volume fractions of the glassy phase in the ingots, and the activation energies of crystallization all point to a 32-atom chemical formula Zr17Cu10Al3Ni2 (Zr53.13Cu31.25Al9.38Ni6.25) as the optimal glass former, with its electron number per unit formula falling slightly below 48. This work confirms the 24-electron rule for single-cluster formulas and provides an easy route towards understanding the complex chemistries of bulk metallic glasses via multiple single-cluster formulas.

通过电弧熔炼制备了Fe75B16.67Si8.33非晶合金,通过真空钎焊获得了钨/低活化钢接头.通过对钎焊接头表面形貌、微观组织、成分和力学性能的表征,发现在1250℃保温10min下所获得的钎焊接头界面无孔洞、裂纹等宏观缺陷,接头组织中生成了Fe固溶体、Fe3B和FeWB金属间化合物,拉伸强度高达450MPa.

夹杂物的去除一直是材料冶金行业研究的焦点问题.经过几十年的发展,传统的冶金除杂技术不能完全满足现代工业生产的需求,仍需要不断探索和研发新的除杂技术.近年来,在合金熔体中施加电子束流强化夹杂物迁移去除的冶金技术因具备清洁高效的特点受到了广泛关注.这种夹杂物去除技术的主要机制有与密度差相关的物相分离机制、流体动力学机制,以及与电性能相关的电迁移机制、电磁挤压力机制、电自由能驱动机制和扩散双电层理论等.依据这一类原理,形成并发展了一系列先进的施加电子束流强化冶金除杂的技术,如连续电流除杂技术、脉冲电流除杂技术、电子束冶金除杂技术等.在此基础上,本文就电子束流对冶金过程中夹杂物去除的影响及相关技术和机理进行了综述,对未来该研究的方向及趋势进行了展望.