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In this work, the AlSi10Mg alloys with distinct molten pool structures, namely fish-scale and lamellar, were fabricated by using selective laser melting (SLM) technology. The effects of solid solution temperature on the microstructural evolution and mechanical properties of the two types of alloys were systematically investigated. The relationship among initial structure, heat treatment and mechanical properties was revealed. The experimental results showed that for the alloy with fish-scale structure, Si diffused more easily after solid solution treatment due to the finer eutectic network, resulting in a larger Si particle size. At 510 °C, the nano Si particles in the fish-scale sample basically disappeared, but a small amount of nano Si particles still existed in the lamellar sample, leading to a bimodal distribution in the Si particle size. Different sizes and distributions of Si particles present different strengthening mechanisms and affect the nucleation and growth of recrystallized grains in the α-Al matrix, leading to significant differences in mechanical properties. The strength of the lamellar sample decreased with increasing the temperature, and the abnormally growth of grains could be found after being treated at 510 °C, resulting in a poor mechanical property. The strength of fish-scale sample first decreased and then increased with the increase of solid solution temperature. When the alloy with fish-scale structure was solid solution treated at 510 °C, Si particles could promote the nucleation of recrystallized grains but hinder their growth, and the ultimate tensile strength decreased from 478.8 MPa of SLMed state to 393.4 MPa, a reduction of 17.8%, while the elongation increased from 7% to 21%, an increase of 300%, showing an excellent overall mechanical property. Therefore, the present study demonstrates that adjusting the SLMed molten pool structure and heat treatment parameters is necessary to obtain a good combination of microstructure and mechanical property. • SLMed AlSi10Mg alloys with different initial structures have distinct mechanical behaviors after heat treatment. • The size and distribution of silicon particles affect the recrystallisation behavior of α -Al. • The relationship among initial structure, heat treatment and mechanical properties was analysed. • Synergistic optimization of SLM and heat treatment parameters was achieved. [ABSTRACT FROM AUTHOR]

A series of Ca 0.98− x MoO 4 :Dy 3+ 0.02 ,M + x (M = Li, Na, K, 0 ≤ x ≤ 0.16) phosphors were synthesized rapidly using microwave radiation method in 30 min. The effects of doping alkali metal ions on the phase structure and luminescent properties of the phosphors were analyzed using X-ray powder diffraction, scanning electron microscopy, fourier transform infra-red spectroscopy, and fluorescence spectrophotometry. The results confirmed that all the samples were pure tetragonal CaMoO 4 structure. The samples consisted of many cubic particles and some irregular polyhedron particles, assembled by fine spherical-like grains. The main emission peak was located at 574 nm, which was attributed to the 4 F 9/2 → 6 H 13/2 transition of Dy 3+ . The addition of alkali metal ions could effectively improve the intensity of the main emission peak. K + had better improvement on emission intensity than Na + and Li + . For the series of Ca 0.98− x MoO 4 :Dy 3+ 0.02 ,K + x phosphors, the optimum doping content of K + was 0.10 with 2.6 times of the emission intensity at 574 nm of the undoped-K + sample. The color coordinates gradually shifted from yellow-green region to the yellow region with the increasing of K + content (0 ≤ x ≤ 0.10). When x = 0.10, the sample shows the strongest yellow-emitting. [ABSTRACT FROM AUTHOR]

In this study, an AlSi10Cu4Mg alloy was prepared by selective laser melting (SLM) using a mixture of pre-alloyed AlSi10Mg and elemental Cu powders, followed by aging at 180 ℃ for 2 h. The high-temperature tensile properties of both the SLMed and SLM-aged samples were tested in the temperature range of 200–400 ℃, and the microstructure changes during deformation were compared. At the temperature of 200 ℃, the SLMed sample exhibits outstanding tensile properties with an ultimate tensile strength (UTS) of 327±2 MPa and an elongation (EL) of 25.5±0.5 %. This is mainly related to the strain hardening that caused by the accumulation of anomalous dislocations near the high-volume fraction of Si nano-particles within the grains. For the SLM-aged sample, the aging treatment is found to further increase the strength, yielding a UTS of 381±3 MPa. The metastable transition of the Al 2 Cu phase indirectly promotes the precipitation of the nano-sized Si phase during the aging process. As the testing temperature increases, the strength increment of the SLM-aged sample gradually diminishes, while the elongation increment increases. Due to the limited intrinsic thermal stability of Si nano-particles and θ′ phase, the coarsening of the precipitates can weaken the strengthening effect. The dynamic recrystallization process can be accelerated by the aging treatment, thereby helping to improve the elongation. [Display omitted] • The high-temperature tensile properties of AlSi10Cu4Mg alloy prepared by SLM were evaluated. • The SLMed AlSi10Cu4Mg alloy exhibited outstanding comprehensive tensile properties at 200 ℃. • The metastable transition of the Al 2 Cu phase facilitates nano-sized Si precipitation during aging process. • The strength increment of SLM-aged sample gradually diminishes with increasing testing temperature while the elongation increment increases instead. [ABSTRACT FROM AUTHOR]

Soft magnetic Fe 72.7 Al 0.8 Si 17.5 B 5 Cu 1 Nb 3- x Ge x ( x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) amorphous alloys were produced by the single roller melt spinning method. The effects of Ge substitution for Nb on the microstructure and magnetic properties were investigated. Magnetic properties of all the alloys annealed at different temperatures were measured by the temperature dependence of initial permeability ( μ i - T curves) from the ambient temperature up to 650 ° C. Structure and crystalline process have been analyzed by XRD patterns and DSC curves, respectively. Partial substitution of Nb by Ge enhanced the Curie temperatures of amorphous phase and crystalline phase, and therefore improved the soft magnetic properties at high temperature. The Fe 72.7 Al 0.8 Si 17.5 B 5 Cu 1 Nb 2.6 Ge 0.4 alloy annealed at 570 ° C for 0.5 h shows the optimum high-temperature μ i , together with higher room-temperature μ i . The origin of the improved magnetic softness both at room- and high-temperature was analyzed. [ABSTRACT FROM AUTHOR]

Modified layers with multiscale structures have been extensively explored and rationally designed on Ti-based orthopedic implants recently, since the remarkable improvement of biomedical properties. In consideration of the inefficiency, costliness and waste products of existing technologies, herein, we proposed the ultrasonic shot peening and induction heating protocol to construct the micro-nano complex oxide structures on Ti6Al4V in term of its advantages of environmental friend, rapid heating, low-cost and easy to process. With the USP pretreatment and induction heating, the nonuniform oxide crystallites firstly appeared on smooth surface and successfully grow up into the well-distributed TiO 2 nanocrystallites, and transformed to netlike structures with submicro-sized worms when subjected to high-power of shot peening, which was significantly influenced by the microstructural evolution of alloy matrix. The submicro/nano-structured oxide layers mainly contained rutile/anatase TiO 2 and little Al 2 O 3 between grain boundaries, successively enhanced the surface roughness and wettability, and tended to form the hydrophilic surfaces. The adhesion strength of the oxide layers to substrates and hardness were also distinctly increased with increasing the IHT period from 20 to 35 s. In vitro BMSCs culturing proved that the prepared submicro/nano-scale oxide layers possessed favorable cell adhesion and proliferation, and further improved the osteogenic differentiation. The novelty of this work was to explored the evolution law of submicro-and nano-scale structures in osteogenic differentiation, and further better clinical application of Ti-based biomaterials. Image 1 • Ultrasonic shot peening and induction heating treatment were jointly proposed. • Microstructure evolution of alloy matrices promoted structure transformation of oxide layers. • Surface roughness, wettability and hardness were markedly improved. • Nano/submicro-structured oxide layers possessed good stem cell compatibility. • Oxide layers with multi-structures further promoted osteogenic differentiation of BMSCs. [ABSTRACT FROM AUTHOR]

• Liquid phase exfoliation method to fabricate Ta 4 C 3 MXene. • Study of characterization of Ta 4 C 3 MXene. • Optical properties of Ta 4 C 3 and its application as a saturable absorber in passive mode-locked fiber lasers. • Erbium-doped fiber laser composed of Ta 4 C 3 saturable absorber can generate stable femtosecond pulses. Ta 4 C 3 as one of the MXene has been widely investigated in the application of materials chemistry, biomedicine, electrochemical energy storage and other fields. However, the study of its optical properties and applications remains rare. In this work, few-layer Ta 4 C 3 MXene are prepared and its optical properties and applications are systematically investigated. We develop few-layer Ta 4 C 3 MXene through the liquid phase exfoliation (LPE) method, and prepare it as Ta 4 C 3 saturable absorber (SA). To obtain femtosecond pulses, the Ta 4 C 3 -SA is inserted further to an erbium-doped fiber laser (EDFL) cavity. It is worth noting that in the experiment the EDFL composed of Ta 4 C 3 -SA can generate stable femtosecond pulses, and the spectral bandwidth and duration of the femtosecond pulses are 1559.6 nm and 350 fs, respectively. Meanwhile, the numerical simulation results consistent with the experimental results. The results reveal that Ta 4 C 3 MXene has great application potential in nonlinear optics and ultrafast photonics. [ABSTRACT FROM AUTHOR]

Abstract: Olivine composites LiFe1−x Mn x PO4/C (x =0, 0.05, 0.1) were prepared by chelation assisted mechanochemical activation method using C2H2O4 as the chelating reagent. The structures of the prepared composites were characterized by X-ray diffraction (XRD). Cyclic voltammetry, ac impedance spectroscopy, galvanostatic charge/discharge performances were studied at room temperature. The discharge capacity of LiFe0.95Mn0.05PO4 was 155.6mAhg−1 and 102.9mAhg−1 at 1C and 10C rate, respectively. The results indicated Mn2+-doping in LiFePO4 could effectively enhance the electrochemical performances of this olivine compound especially at high charge/discharge rate. In addition, charge/discharge method was also used to characterize the low temperature properties of the different samples. The results showed that the lower the operation temperature was, the poorer the performances were. Furthermore, ac impedance measurement was used to understand the factors of the poor performances at low temperature. [ABSTRACT FROM AUTHOR]

Abstract: Alien atom doping has been adopted to modify the electrochemical performance of olivine type LiFePO4 for cathode material. Here, we report that vanadium-doping can improve the performance of LiFePO4/C immensely. LiFePO4/C and V-doped LiFePO4/C cathode materials were first synthesized by carbothermal reduction method. Physico-chemical characterizations were done by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrochemical behavior of the cathode materials was analyzed using cyclic voltammetry (CV) and galvanostatic measurements. ICP and XRD analyses indicated that V ions were sufficiently doped in LiFePO4 and did not alter its crystal structure and exhibited the variation of lattice parameters with the doped degree. From the CV, the V ion doping affected the Li+ ionic diffusion coefficient during both the delithiation and lithiation processes and it became larger with an appropriate amount doping. From the results, it is noted that vanadium ions doping can improve performance of LiFePO4, especially on the aspect of stable cycle-life at higher C rate. [Copyright &y& Elsevier]

It is always challenging to synchronously improve the strength, ductility and corrosion resistances, in the development of magnesium alloys. Herein, a concept called hierarchical precipitate embedded fine grain microstructure is proposed and implemented in an Mg-13Al (wt%) alloy by equal channel angular pressing and aging. Compared to the as-cast alloy, the modified alloy with the designed microstructure has high strength, good ductility, and improved corrosion resistance. The enhancement of mechanical properties is mainly attributed to the synergistic effect of fully recrystallized fine grains (~3.7 µm) and hierarchical β phase (Mg 17 Al 12) precipitates. Although the formation of the hierarchical β phase precipitates in fine-grain Mg matrix can accelerate the initial corrosion in 3.5 wt% NaCl solution due to the galvanic corrosion, the ultimate corrosion resistance is successfully improved by the consumption of exposed Mg anodes and the synergistic barrier effect from the newly-formed corrosion products and corrosion-resistant β phases. ga1 • A concept called hierarchical precipitates embedded fine grain (HP-FG) is proposed. • This strategy provides a way to synchronously enhance multiproperties of Mg alloys. • HP-FG Mg-13Al alloy exhibits enhanced strength, ductility and corrosion resistance. • The unique microstructure confers the excellent multi-properties. • The improved corrosion resistance mainly stems from the hierarchical precipitates. [ABSTRACT FROM AUTHOR]