查看更多>>摘要：? 2022 Elsevier B.V.The damping capacity of high Mg alloyed Al-Mg alloy (Al-9.2Mg-0.8Mn-0.2Zr-0.15Ti) prepared by high strain rate hot rolling (HSRR) and subsequent cold rolling (CR) are carefully studied. Both the strain amplitude dependent internal friction (ADIF) at room temperature and the temperature dependent internal friction (TDIF) at elevated temperature are detected by a dynamic mechanical analyzer (DMA). The results indicate that the subsequent cold rolling can significantly improve the damping capacity of the alloy. The as-CRed alloy exhibits higher strength and better damping capacity than the as-HSRRed alloy, with the ultimate tensile strength (UTS) of 606 ± 6 MPa, the elongation to rupture of 11.6 ± 0.6% and the Q-1 value of 0.019 at room temperature with the strain of 1 × 10-3 and the frequency of 1 Hz. The room temperature damping of the as-CRed alloy is mainly ascribed to the low stacking fault energy (SFE), the high dislocation density and the finer broken second phase particles. Moreover, the as-CRed alloy also presents excellent high temperature damping, with the maximum Q-1 value of 0.212 ± 0.003 at 361 ℃ with the frequency of 1 Hz. The relatively high damping capacity of the cold rolled sheet for a given frequency and temperature can be attributable to the special microstructure characteristics including the high dislocation density, the elongated lamellar grains with shear bands and the high fraction of LAGBs.
查看更多>>摘要：? 2022 Elsevier B.V.To pursue a combination of strength and plasticity, a near-eutectic high-entropy alloy Cu40Al20Ti20V20 was developed by using a stoichiometric ratio of the L21 Cu2AlTi ordered phase. The results showed that a soft-hard alternating BCC (α)+L21 (β) dual-phase structure was realized. The as-cast alloy was composed of BCC (αp) dendrites, and a lamellar and rod-like BCC+L21 Cu2AlTi (α + β) eutectic structure with a small amount of FCC Cu-rich phase embedded within. Due to the soft-hard dual-phase structure and large number of phase interfaces of the eutectic, the as-cast alloy possessed a high yield strength of 1300 MPa and plasticity of 6.3%. Annealing facilitated the precipitation of a substantial number of L21 nanoparticles (βII) in the dendrites and the diffusion of Cu atoms from the Cu-rich phase to the matrix. The desolation transformation of βII and the Cu diffusion during annealing increased the formation of excess L21 hard-phase to ~50 vol%. Many micro-pores were also formed, which facilitated crack initiation and deteriorated the strength and plasticity of the homogenized alloy.
查看更多>>摘要：? 2022 Elsevier B.V.FeCo alloys are important soft magnetic materials with the highest saturation magnetizations, high Curie temperature, high permeability, and low losses. In this study, 3D interconnected nanoporous (3DNP) FeCo soft magnetic materials were produced by liquid metal dealloying (LMD). Ni atoms were selectively dissolved from (FeCo)xNi100?x precursor alloys into Mg metallic melt, and Fe and Co atoms self-organized 3DNP structures. Morphology and grain boundary characteristics depended on the LMD processing temperature and Ni concentration in precursor alloy. Developed 3DNP FeCo materials demonstrated soft magnetic properties with high saturation magnetization over 220 emu/g. Although 3DNP structure increases hysteresis loss due to its porosity, it leads to lower eddy current loss than bulk FeCo at high frequencies. The LMD process has advantages for synthesizing nanostructured FeCo with high magnetization and low coercivity.
查看更多>>摘要：? 2022In order to study the effect of microstructure on mechanical properties of heat -treated Ti-47.5Al-3Nb-1.5Cr (at%.) samples, a heat treatment system was designed at 1573 K, 1623 K and 1673 K for 15 min, 30 min and 60 min. After the heat preservation, the samples were air-cooled. Among them, when the as-cast samples are keep at 1623 K for a period of time, the interlamellar spacing is refined. In addition, due to the heat treatment in the two-phase region, the elements are further diffused and more uniform in the sample. The room temperature tensile tests exhibits that the mechanical properties of the samples obtained by holding at 1623 K for 1 h and then air-cooling obtained the best improvement, the tensile strength and elongation at break from 372.54 MPa and 0.70% to 533.86 MPa and 1.04%. After analyzing the mechanical properties and structure of the alloy, it can be concluded that refining the interlamellar spacing and solid solution strengthening can effectively improve the elongation and tensile strength.
查看更多>>摘要：? 2022 Elsevier B.V.The non-fast thermal response and unstable mechanical properties of flexible transparent heaters (FTHs) make it difficult for them to meet the requirements for wearable electronics. In this paper, the influences of heater thickness and resistance of Ag nanowire networks, on the thermal response, optical and mechanical flexible properties are investigated systematically. The relationships between the mechanisms behind the thermal response (bending behaviors) and the thickness, which is important for enhancing the thermal and flexible performances of FTH, are explored. The optimized Ag NW/UV-curable resin -based FTHs, with a thickness of 2 μm and sheet resistance of 9.9 Ω/□, exhibit a quick thermal response time within 12 s, a high optical transmittance of 86.4% and superior mechanical properties. The resistance of the FTH shows almost no change after bending 1000 times at a curvature radius of 0.5 mm. The fast-heating characteristics associated with its transparency and flexibility make the Ag NW/UV-curable resin -based FTHs a potential candidate in wearable electronics.
查看更多>>摘要：? 2022 Elsevier B.V.The influence of isotropic physical pressure, applied either during the high-pressure-high-temperature (HPHT) annealing or the measuring processes, on the magnetic properties of NdFeO3 single crystal, has been investigated. In comparison to the complete spin reorientation (SR) in an as-grown NdFeO3 single crystal, the thermomagnetic M(T) and isothermal M(H) curves for a HPHT-annealed sample indicates an incomplete SR transition from a Γ2-rich to a Γ4-rich Γ24 mixed phase. Moreover, the M(T) curves of the as-grown sample under different measuring hydrostatic pressures suggest that the SR transition takes place in the sequence of Γ2→Γ1 +Γ2 +Γ4→Γ1 +Γ4→Γ4, instead of the Γ2→Γ2 +Γ4→Γ4, without applying pressure during the measuring process. Such manipulation of the magnetic configuration reveals that the 3d-4f interaction in the NdFeO3 could be greatly affected by the isotropic pressure. These findings may provide a new perspective and possibility for the tuning of the magnetism and corresponding microscopic interactions.
查看更多>>摘要：? 2022 Elsevier B.V.Two kinds of (TiB + TiC + Y2O3)/α-Ti composites with different TiB and TiC contents and the corresponding matrix alloy were prepared by induction skull melting. The results showed that the matrix alloy possessed a typical widmanstatten structure while the composites displayed a basket-weave structure characterized by α lamellae with different orientations. Obvious TiB/TiC structures were observed with the increase of reinforcements, which were very stable in the tensile and creep processes at high temperature. The ultimate tensile strength at 650 ℃ increased from 589 MPa to 730 MPa and 812 MPa with the increase of reinforcements. The enhancement in strength of the composites was elucidated on the load transfer strengthening of the reinforcements. The creep properties of the composites at 650 ℃ have been significantly improved due to the impediment of reinforcements and silicides to dislocation movement. The strengthening effect increased with the increase of reinforcements and stress. At 650 ℃/290 MPa, compared with the matrix alloy, the creep life of composite with highest reinforcements content was increased by 931% and the steady-state creep rate was reduced by 93%. According to the different stress levels, the composites exhibited different creep behaviors. At 230 MPa, the sub-grains were obvious and the number of actuated dislocations is small. At 290 MPa, the dislocation pile-up was serious and the obviously coarsened silicides lost their pinning effect.
查看更多>>摘要：? 2022 Elsevier B.V.Ni-based hydroxides nanomaterials are widely used in alkaline storage devices. Under the guidance of density functional theory calculations and experimental investigations, here, (Ni0.8Co0.1Mn0.1)(OH)2 is designed and prepared on CuO nanowire arrays, demonstrating Co and Mn co-substitution resulted in enhanced capacity and stability of Ni(OH)2. The enhanced performance is mainly thanks to the low deprotonation energy and the facile electron transport, which results from the synergistic interactions among Ni, Co and Mn. Ni-Zn battery and alkaline hybrid supercapacitor with (Ni0.8Co0.1Mn0.1)(OH)2 (8.4 mg cm?2) as positive electrode can achieve infusive energy density of 605.2 and 270.1 Wh kg?1, respectively. The finding lay a foundation for further the design and fabrication of high-performance Ni-based nanomaterials for alkaline energy storage.
查看更多>>摘要：? 2022 Elsevier B.V.Cf/SiC and Cf/ZrC-SiC composites were fabricated via a novel combined process, which achieved a lower open porosity below 8% compared with the single PIP process. Nevertheless, Cf/SiC and Cf/ZrC-SiC composites did not possess the superior mechanical properties, but the poorer ones. Meanwhile, the veiled factors affecting the mechanical properties have been clarified. The large SiC particles (as large as ~40 μm) degraded the strength of matrix, thereby deteriorating mechanical properties of Cf/ZrC-SiC and Cf/SiC composites. Moreover, higher processing temperature (1700 °C) of the combined process and large CTE differences resulted in larger thermal residual stress in the composites compared with single PIP process with lower processing temperature (1200 °C), which also restrained the improvements of mechanical properties.
查看更多>>摘要：? 2022 Elsevier B.V.Lithium-ion hybrid supercapacitors (LIHSs) have received significant attention in electrochemical energy-related areas. However, the sluggish anode kinetics hinders the improvement of power density and cycling stability. Herein, an in-situ catalytic graphitization with a salt-template strategy was applied to prepare the porous graphitic carbon nanosheets. The results demonstrated that the addition of KCl led to a higher specific surface area and higher porous structure. The as-prepared potassium-induced porous graphitic carbon flakes (PPGCs) exhibited an electrochemical plateau capacity of 240.1 mAh g?1 and an electrochemical slope capacity of 129.0 mAh g?1. PPGCs also delivered superior rate performance of 60.8 mAh g?1 even at 5.0 A g?1, which was much better than graphitic carbon flakes (GCFs) and potassium-induced graphitic carbon flakes (PGCFs). When assembled into LIHSs devices with commercial activated carbon, the energy density reached 75.6 Wh kg?1, and the power density was as high as 5.05 kW kg?1. After 10,000 cycles at 5.0 A g?1, the energy density was maintained at 39.2 Wh kg?1, revealing excellent long-term cycling performance. This work may provide a promising solution to obtain graphitic carbon with a high graphitization degree and highly porous structure.
NSTL
Elsevier