Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:6.155

The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

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      01 July 2020, Volume 48 Issue 0 Previous Issue    Next Issue
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    Research Article
    Superhydrophobic diamond-coated Si nanowires for application of anti-biofouling’
    Wenjing Long, Haining Li, Bing Yang, Nan Huang, Lusheng Liu, Zhigang Gai, Xin Jiang
    J. Mater. Sci. Technol., 2020, 48 (0): 1-8.  DOI: 10.1016/j.jmst.2019.10.040
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    The effect of the surface wettability of plasma-modified vertical Si nanowire array on the bio-fouling performance has been investigated. The Si nanowires prepared by a metal-assisted chemical etching technique exhibit a super-hydrophilic surface. The treatment in CH4/H2 gas plasma environment leads to the decoration of graphite and diamond nanoparticles around Si nanowires. The detailed interface between graphite/diamond and Si nanowire was characterized by HRTEM technique. These surface-modified nanowire samples show an increased water contact angle with ultrananocrystalline diamond decorated ones being superhydrophobic. The immersion test in chlorella solution reveals that the diamond-coated Si nanowires possess the least attachment of chlorella in comparison with other Si nanowires. This result confirms that the coating of Si nanowires with diamond nanoparticles shows the best behavior in anti-biofouling. Importantly, this work provides a method fabricated super-hydrophobic surface for the application of biofouling prevention.

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    Influence of the low voltage pulsed magnetic field on the columnar-to-equiaxed transition during directional solidification of superalloy K4169
    Kuiliang Zhang, Yingju Li, Yuansheng Yang
    J. Mater. Sci. Technol., 2020, 48 (0): 9-17.  DOI: 10.1016/j.jmst.2020.02.009
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    The low voltage pulsed magnetic field (LVPMF) disrupts the columnar dendrite growth, and the columnar-to-equiaxed transition (CET) occurs during the directional solidification of superalloy K4169. Within the pulse voltage ranging from 100 V to 200 V, a transition from columnar to equiaxed grain was observed, and the grain size decreased as the pulse voltage rised. As the pulse frequency increased, the CET occurred, and the grains were refined. However, the grains became coarse, and the solidification structure was columnar crystal again when frequency increased to 10 Hz. The LVPMF had an optimal frequency to promote CET. The LVPMF on the CET was affected by the withdrawal speed and increasing the withdrawal speed enhances the CET. The distribution of electromagnetic force and flow field in the melt under the LVPMF were modeled and simulated to reveal the CET mechanism. It is considered that the CET should be attributed to the coupling effects of magnetic vibration and melt convection induced by the LVPMF.

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    Nanostructures and nanoprecipitates induce high strength and high electrical conductivity in a CuCrZr alloy
    Z.Y. Zhang, L.X. Sun, N.R. Tao
    J. Mater. Sci. Technol., 2020, 48 (0): 18-22.  DOI: 10.1016/j.jmst.2019.12.022
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    The mixed nanostructure mainly consisting of nanotwins and nanograins was obtained in a solid solution CuCrZr alloy by means of dynamic plastic deformation at cryogenic temperature. After subsequent aging treatments, the precipitation of Cr at nanometer scale provided further strengthening and brought substantial recovery of electrical conductivity. The aged nanostructured CuCrZr alloy exhibited a high tensile strength of 832 MPa and a high electrical conductivity of 71.2% IACS. The details of precipitation tuned by nanotwin boundaries were demonstrated in this work. The combined strengthening of nanostructures and nanoprecipitates was discussed.

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    A novel friction stir diffusion bonding process using convex-vortex pin tools
    S.D. Ji, Q. Wen, Z.W. Li
    J. Mater. Sci. Technol., 2020, 48 (0): 23-30.  DOI: 10.1016/j.jmst.2020.01.042
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    In this work, a novel friction stir diffusion bonding (FSDB) method was proposed to eliminate hook when joining thin sheets. Three tools, with several convex-vortex pins were innovatively designed to improve the diffusion bonding effect of the lap interface. Results showed that sound joints, excellently bonded at the lap interface and without hook, were obtained. The lap interfaces on the joints welded using the T-tool and F-tool almost remained intact, thereby indicating that they were formed by diffusion bonding. The material flow behavior was also simulated by FLUENT software and the results showed that the material flow along thickness was significantly enhanced by increasing the pin number. The joint welded by the T-tool showed shear fracture mode. Sound bonding was formed at the lap interface when using the F-tool and thus the joint showed tensile fracture.

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    Two-stage Hall-Petch relationship in Cu with recrystallized structure
    Y.Z. Tian, Y.P. Ren, S. Gao, R.X. Zheng, J.H. Wang, H.C. Pan, Z.F. Zhang, N.T suji, G.W. Qin
    J. Mater. Sci. Technol., 2020, 48 (0): 31-35.  DOI: 10.1016/j.jmst.2019.12.023
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    Although Cu was studied extensively, the Hall-Petch relationship was mainly reported in the coarse-grained regime. In this work, fully recrystallized Cu specimens with a wide grain size regime of 0.51-14.93 μm manifest a two-stage Hall-Petch relationship. There is a critical grain size of 3 μm that divides stages I and II where the Hall-Petch slope k value are quite different. The stage II is supposed to be validified down to 100 nm at least by comparing with a Cu-Ag alloy. The critical grain size varies in different materials systems, and the underline mechanisms are discussed based on the dislocation glide modes.

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    Investigation of beta fleck formation in Ti-17 alloy by directional solidification method
    Xuchen Yin, Jianrong Liu, Qingjiang Wang, Lei Wang
    J. Mater. Sci. Technol., 2020, 48 (0): 36-43.  DOI: 10.1016/j.jmst.2019.12.018
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    Beta flecks are one of the most common defects occur in some α + β and β titanium alloys. In this study, formation of beta flecks in Ti-17 alloy was investigated by directional solidification experiments. Samples were directionally solidified under a constant temperature gradient of 2 × 10 4 K/m and a wide range of withdrawal rates (R) from 3 mm/h to 150 mm/h. We find that macrostructure of the directionally solidified Ti-17 samples can be characterized by “four zones and two lines” after the heat treatment. Profile of the solid-liquid interface transits from planar to cellular to dendritic shape with solidification rate increasing from 3 mm/h to 150 mm/h. The critical rates for planar to cellular (Rc1) transition and cellular to dendritic (Rc2) transition can be well predicted based on the traditional solidification theory. Dark and light contrast areas in macrostructure are directly related to elemental segregation. Dark contrast areas are rich of Cr, Zr but lean of Mo, while no apparent segregation is found in light contrast areas and the mean level of Cr, Zr is lower and Mo is higher in this area than that in dark contrast areas. We conclude that β-flecks in Ti-17 titanium alloy are induced by segregation of alloying elements with k<1 and their shape and size are determined by solidification conditions. Based on the findings of the present article and other literatures, three types of β-flecks are proposed and their formation mechanisms are discussed.

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    Microstructural evolution and mechanical properties of 300M steel produced by low and high power selective laser melting
    Guanyi Jing, Wenpu Huang, Huihui Yang, Zemin Wang
    J. Mater. Sci. Technol., 2020, 48 (0): 44-56.  DOI: 10.1016/j.jmst.2019.12.020
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    300M ultra-high strength steel has been widely used in critical structural components for aviation and aerospace vehicles, owing to its high strength, excellent transverse plasticity, fracture toughness and fatigue resistance. Herein, low and high power selective laser melting (SLM) of 300M steel and their microstructural evolution and mechanical properties have been reported. The results show that the optimal energy density range with the highest relative density for SLMed 300M steel is between 60 and 160 J/mm3. Furthermore, molten pools for deposition exhibit a conduction mode with semi-elliptical shape at a lower laser power of 300-600 W but a keyhole mode with “U” shape at a higher laser power of 800-1900 W. The heterogeneous microstructure of as-built samples is characterized by a skin-core structure which is that tempered troostite with the coarse non-equiaxed grains in the molten pool is wrapped by tempered sorbite with the fine equiaxed grains in the heat-affected zone. The skin-core structure of SLMed 300M steel has the characteristics of hard inside and soft outside. The average microhardness of samples varies from 385 to 341 HV when laser power increases from 300 to 1900 W. Interestingly, ultimate tensile strength (1156-1193 MPa) and yield tensile strength (1085-1145 MPa) of dense samples fabricated at different laser powers vary marginally. But, the elongation (6.8-9.1%) of SLMed 300M steel is greatly affected by the laser power.

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    Letter
    High entropy (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12: A novel high temperature stable thermal barrier material
    Heng Chen, Zifan Zhao, Huimin Xiang, Fu-Zhi Dai, Wei Xu, Kuang Sun, Jiachen Liu, Yanchun Zhou
    J. Mater. Sci. Technol., 2020, 48 (0): 57-62.  DOI: 10.1016/j.jmst.2020.01.056
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    Ytterbium aluminum garnet (Yb3Al5O12) is considered as a promising thermal barrier material. However, the main limitations of Yb3Al5O12 for thermal barrier applications are relative low thermal expansion coefficient and high thermal conductivity. In order to overcome these obstacles, herein, a new high entropy (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 ceramic was designed, and then powders and bulk were prepared through solid-state reaction method and spark plasma sintering (SPS), respectively. The thermal expansion coefficient of HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 is (8.54 ± 0.29) × 10-6 K-1 at 673 K-1273 K, which is about 9% higher than that of Yb3Al5O12. The thermal conductivity of HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 ceramic is 3.81 W·m-1 K-1 at 300 K, which is about 18 % lower than that of Yb3Al5O12. Moreover, there is no reaction between HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 and thermally grown (TG) Al2O3 even at 1600 °C. After annealing at 1590 °C for 18 h, the average grain size of HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 increases only from 1.56 μm to 2.27 μm. Close thermal expansion coefficient to TG Al2O3, low thermal conductivity, good phase stability, excellent chemical compatibility with TG Al2O3 and slow grain growth rate make HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 promising for thermal barrier applications.

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    Research Article
    Microstructure, tensile properties and mechanical anisotropy of selective laser melted 304L stainless steel
    Juan Hou, Wei Chen, Zhuoer Chen, Kai Zhang, Aijun Huang
    J. Mater. Sci. Technol., 2020, 48 (0): 63-71.  DOI: 10.1016/j.jmst.2020.01.011
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    The microstructure and mechanical properties of 304 L stainless steel fabricated by selective laser melting are investigated in this study. With the optimized laser processing parameters, a relative density of 99.9% is achieved with fine austenite grains and nanoscale cellular subgrains in size of approximately 0.5 μm. The presence of δ-ferrite and σ phase precipitates is identified by the x-ray diffraction and transmission electron microscopy. Moreover, the microstructure is identified as an austenite matrix with about 4% δ ferrite and a trace amount of σ phase by using electron backscattered diffraction analysis. These small σ phase particles are mainly distributed along austenite grain boundaries. Furthermore, the presence of nanoscale cellular subgrains contributes to the good tensile strength and ductility of the selective laser melted 304 L, along with precipitate strengthening and strain hardening. Tensile property anisotropy is also identified in this 304 L, which is attributed to the microstructure difference on vertical and horizontal planes.

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    Methanogenic archaea and sulfate reducing bacteria induce severe corrosion of steel pipelines after hydrostatic testing
    Enze Zhou, Jianjun Wang, Masoumeh Moradi, Huabing Li, Dake Xu, Yuntian Lou, Jinheng Luo, Lifeng Li, Yulei Wang, Zhenguo Yang, Fuhui Wang, Jessica A. Smith
    J. Mater. Sci. Technol., 2020, 48 (0): 72-83.  DOI: 10.1016/j.jmst.2020.01.055
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    Complex interactions within a microbial consortium can induce severe corrosion in oil pipelines. This study investigated the mechanism of microbiologically influenced corrosion (MIC) that led to failure of X52 steel pipelines after hydrostatic testing. Laboratory hydrostatic testing with untreated lake water and underground water were used to simulate and study the events that led to the actual corrosion. Biofilm analysis, weight loss, and several electrochemical measurements demonstrated rapid corrosion rates after hydrostatic testing. Analysis of microbial community structures revealed that methanogenic archaea and sulfate reducing bacteria (SRB), introduced by the hydrotest water, formed corrosive biofilms on X52 steel coupon surfaces that induced severe pitting.

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    Three-dimensional carbon framework as high-proportion sulfur host for high-performance lithium-sulfur batteries
    Xianbin Liu, Zechen Xiao, Changgan Lai, Shuai Zou, Ming Zhang, Kaixi Liu, Yanhong Yin, Tongxiang Liang, Ziping Wu
    J. Mater. Sci. Technol., 2020, 48 (0): 84-91.  DOI: 10.1016/j.jmst.2020.03.001
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    Lithium-sulfur (Li-S) batteries are anticipated as one of the most promising candidates for the high-energy-density storage systems. However, the insulating nature and shuttling effect of sulfur severely limits their performance. The incorporation of sulfur with carbon materials has been deemed as one of the most powerful strategies to improve electrical conductivity and suppress soluble polysulfide shuttling. Herein, a novel three-dimensional carbon framework (3DCF) is prepared and employed as a sulfur host (3DCF@S) for Li-S batteries. The 3DCF not only supplies abundant paths for lithium ion diffusion and electron transport, but also strengthens polysulfide immobilization during the lithium/sulfur conversion reactions. As a result, the 3DCF@S with high sulfur content of 90% exhibits a high capacity of 1366 mA h/g at 0.1 C and excellent cycling stability with a satisfactory capacity of 601 mA h/g after 600 cycles at 2.0 C. The resultant Li-S button battery based 3DCF@S electrode could power a light-emitting diode for 2 h. The acquired 3DCF@S is expected to be widely used in Li-S batteries and this study will promote developments of carbon/sulfur composites for Li-S batteries.

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    Large electromechanical strain at high temperatures of novel <001> textured BiFeGaO3-BaTiO3 based ceramics
    Jiangguli Peng, Wenbin Liu, Jiangtao Zeng, Liaoying Zheng, Guorong Li, Anthony Rousseau, Alain Gibaud, Abdelhadi Kassiba
    J. Mater. Sci. Technol., 2020, 48 (0): 92-99.  DOI: 10.1016/j.jmst.2019.12.033
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    BiFeGaO3-BaTiO3 (BFG-BT) based ceramics with a large piezoelectric coefficient are potential high performance lead-free piezoelectric compounds. In this work, textured and random BFG-BT ceramics were realized by the solid state reaction method with and without BaTiO3 (BT) templates. Textured ceramics were obtained by a reactive templated grain growth (RTGG) method leading to a high-temperature electromechanical strain of S = 0.27 % at 40 kV/cm and to an effective piezoelectric coefficient (d33*) up to 685 pm/V at 180 °C. The easy movement of oriented domains enhanced the electromechanical strain under an applied electric field in textured sample (Lotgering factor f = 66.3 %). Structural investigations reveal that the proportion and degree of distortion of BFG-BT rhombohedral phase (R3c) reached its maximum in textured ceramics, resulting in large ferrodistortive displacements under electric fields. In addition, the dense nanodomains with low domain wall energies, inferred from the high-resolution transmission electron microscope (HR-TEM) observations, contribute to the extra displacement of the textured sample under an applied electric field. In textured ceramics, the remnant polarization was stable (about 17 μC/cm2) from room temperature to 180 °C, contributing to the stable ferroelectric property at high temperatures. Through the introduction of BT templates, high-density nanodomains were formed and the Burns temperature was enhanced in textured ceramics. The electromechanical strain, polarization and dielectric behavior were correlated to the textured or random forms of the BFG-BT based ceramics.

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    High-performance UV detectors based on 2D CVD bismuth oxybromide single-crystal nanosheets
    Long Chen, Chengtao Yang, Chaoyi Yan
    J. Mater. Sci. Technol., 2020, 48 (0): 100-104.  DOI: 10.1016/j.jmst.2020.03.008
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    Two-dimensional (2D) ternary wide-bandgap semiconducting materials have great potential in power device, flexible electronic device, short-wavelength light emitting diodes (LEDs) and photodetectors due to the controllable bandgap, strong light-material interaction, and controlled freedom degree of stoichiometry variation. However, it is still a great challenge to precisely control the growth of high-quality 2D ternary wide-bandgap semiconducting materials due to the variety of components, which hinders their development for practical applications. In this work, high-quality 2D ternary bismuth oxybromide single-crystal nanosheets with a high yield were prepared by space-confined chemical vapor deposition (CVD) method. The devices based on 2D ultrathin BiOBr single-crystal nanoflakes show a high UV detecting performance including low dark current (Idark) of 1.46 pA and high responsivity (R), external quantum efficiency (EQE) and detectivity (D*) of 14.96 A W-1, 5460%, and 5.74 × 10 10 Jones, respectively, as well as fast response process (τrise =80 ms, τdecay =40 ms). The excellent UV performance can be ascribed to the photogating effect by trapped states, which endow it with great potential for high-performance UV detectors.

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    Size controllable synthesis and photocatalytic performance of mesoporous TiO2 hollow spheres
    Nattakan Kanjana, Wasan Maiaugree, Phitsanu Poolcharuansin, Paveena Laokul
    J. Mater. Sci. Technol., 2020, 48 (0): 105-113.  DOI: 10.1016/j.jmst.2020.03.013
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    Hollow mesoporous TiO2 spheres (THs) were prepared via template-directed deposition of TiO2 nanoparticles on the surface of carbon spheres. The carbon spheres were used as hard templates. Their diameters were controlled by pH adjustment prior to a hydrothermal process. Physical properties, such as crystallinity, optical characteristics, microstructure and surface morphology of the samples were characterized. The results showed that the diameter of the carbon template could be well controlled in the range of 397-729 nm by adjusting the initial pH value of the dextrose solution from 3 to 10. Hollow TiO2 spheres with average diameters ranging from 171 to 668 nm and shell thicknesses ranging from 28 to 47 nm formed by heat treatment at 450 °C. The photocatalytic performance of hollow TiO2 spheres and TiO2 nanoparticles was examined under UVA irradiation using a methyl orange aqueous solution as an artificial dye. The study revealed that the THs synthesized using a dextrose solution at pH 7 had a higher photocatalytic activity compared to other samples since it had the lowest shell thickness and the proper optical band gap of 3.12 eV with the longest lifetime of electron-hole pair separation.

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    Superior mechanical and thermal properties than diamond: Diamond/lonsdaleite biphasic structure
    Bo Yang, Xianghe Peng, Yinbo Zhao, Deqiang Yin, Tao Fu, Cheng Huang
    J. Mater. Sci. Technol., 2020, 48 (0): 114-122.  DOI: 10.1016/j.jmst.2020.03.005
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    It has been found recently in experiments that diamond/lonsdaleite biphase could possess excellent thermal-mechanical properties, implying that the properties of carbon materials can be improved by reasonably designing their internal structures. The mechanism of the excellent performance arising from biphasic structure is still unknown and needs to be revealed. In this paper, we established a series of possible diamond/lonsdaleite biphasic structures and revealed the optimization mechanism of the biphasic structure using first principles calculations. It shows in our ab-initio molecular dynamics simulations that the lonsdaleite cannot exist stably at room temperature, which could explain why pure lonsdaleite can hardly be found or synthesized. Detailed analysis shows that partial slip would occur in the lonsdaleite region if the applied strain is sufficiently large, leading to the transition from biphasic phase to cubic phase. Then, further shear strain would be applied along the hard shear direction of the cubic structure, resulting in an ascent of stress. The results presented could offer an insight into the structural transformation at high temperature and large strain.

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    Effects of dealloying and heat treatment parameters on microstructures of nanoporous Pd
    Y.Z. Chen, X.Y. Ma, W.X. Zhang, H. Dong, G.B. Shan, Y.B. Cong, C. Li, C.L. Yang, F. Liu
    J. Mater. Sci. Technol., 2020, 48 (0): 123-129.  DOI: 10.1016/j.jmst.2020.03.012
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    Microstructures of nanoporous Pd are essentially important for its physical and chemical properties. In this work, we show that the microstructures of nanoporous Pd can be tuned by adjusting compositions of the precursor alloys, and dealloying and heat treatment parameters. Both the ligament and pore sizes decrease with increasing the electrochemical potential upon dealloying and the concentration of noble component in the precursor alloys. Heat treatment causes coarsening of the nanoporous structure. Above a critical temperature, the nanoporous structures are subjected to significant coarsening. Below the critical temperature, surface diffusion is believed to dominate the coarsening process. Above the critical temperature, the nanoporous structure coarsens remarkably at a rather high rate, which is ascribed to a multiple-mechanism controlled process.

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    Rough surface of copper-bearing titanium alloy with multifunctions of osteogenic ability and antibacterial activity
    Hui Liu, Rui Liu, Ihsan Ullah, Shuyuan Zhang, Ziqing Sun, Ling Ren, Ke Yang
    J. Mater. Sci. Technol., 2020, 48 (0): 130-139.  DOI: 10.1016/j.jmst.2019.12.019
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    Implant-related infection and early bone integration are the main risk factors of implants for long-term service, to overcome these difficulties, SLA-TiCu surface was prepared by sandblasting and large-grits etching (SLA) treatment on a novel antibacterial titanium-copper alloy (TiCu), which is the most prevalent surface treatment with micro/submicron hierarchical structures to titanium-based implants. Effects of SLA-TiCu surface on the adhesion, proliferation, apoptosis and differentiation of MC3T3-E1 cells as well as the antibacterial activity against a common orthopedic pathogen (Staphylococcus aureus) were studied. Compared to the following surfaces: sandblasting and large-grits etched pure titanium (SLA-Ti), mechanically ground pure titanium and TiCu alloy (M-Ti and M-TiCu), these results indicated that SLA-TiCu surface obviously enhanced the bone-related gene expressions (alkaline phosphates (ALP), collagen type I (COL I), Runt-related transcription factor 2 (RUN × 2), and osteopontin (OPN)). Moreover, SLA-TiCu surface could maintain a sustainable release of Cu2+ ions and effectively inhibited the viability of bacteria. This study demonstrated that SLA-TiCu surface possessed multifunctional characteristics of improved osteogenic ability and antibacterial activity, making it promising as a novel implant material for hard tissue repairs such as orthopedics and dental implants.

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    Letter
    Surface modification of plasma nitriding on AlxCoCrFeNi high-entropy alloys
    Jinxiong Hou, Wenwen Song, Liwei Lan, Junwei Qiao
    J. Mater. Sci. Technol., 2020, 48 (0): 140-145.  DOI: 10.1016/j.jmst.2020.01.057
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    Plasma nitriding is successfully employed in treating AlxCoCrFeNi high-entropy alloys (HEAs) with finely-divided Al content (i.e., x values in molar ratio, x = 0.1- 0.8) to develop wear-resistant structural materials. Nitridation greatly removes the Al from the matrix that completely deplete the Ni-Al enriched phase, forming nanoscaled nitrides (AlN and CrN) precipitations near the surface. Nitriding promotes the hardness of present alloys with values widely ranging from 276 HV to 722 HV. Interestingly, the higher content the Al, the smaller thickness the nitrides layer, but the higher hardness due to the increased amount of hard nitrides phases and volume fraction of BCC phase. Significantly, plasma nitriding considerably improves the wear resistance of AlxCoCrFeNi HEAs by 4-18 times.

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    Research Article
    The effect of Co and Cr substitutions for Ni on mechanical properties and plastic deformation mechanism of FeMnCoCrNi high entropy alloys
    H.F. Zhang, H.L. Yan, H. Yu, Z.W. Ji, Q.M. Hu, N. Jia
    J. Mater. Sci. Technol., 2020, 48 (0): 146-155.  DOI: 10.1016/j.jmst.2020.03.010
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    The elastic constants, ideal tensile strength (ITS), stacking fault energy (SFE), lattice constant and magnetic moment of FeMnCoCrNi high entropy alloys with varying Co and Cr contents at 0 and 300 K were systematically investigated by first-principle calculations. For the alloys with Co substitution for Ni, at both temperatures the elastic stability of the face-centered cubic (fcc) phase, bulk elastic modulus (B), Young's modulus (E), shear modulus (G) and ITS increase monotonically with increasing Co content. However, the Cauchy pressure (CP), Pugh ratio (B/G), Poisson ratio (v), Zener anisotropy ratio (AZ) and elastic anisotropy ratio (AVR) decrease monotonically. The SFE also decreases with the increase of Co, resulting in the change of plastic deformation mechanism from dislocation slip to mechanical twinning, and then to hcp-martensitic transformation. This elucidates the underlying mechanism of the effect of Co addition on the strength and micromechanical behavior of FeMnCoCrNi alloys. Compared with Co, the Cr substitution for Ni leads to the more complex change of elastic constants and ITS. The increase of Cr shows the similar effect on SFE and deformation mechanism as that of Co. The variation of valence electron concentration and magnetism affect the SFE. The increase of either Co or Cr leads to the reduced magnetic moments of Fe and Mn. This could be responsible for the monotonic decrease of both lattice constant and SFE as the Co content increases. However, for the Cr addition case, multiple factors may affect the evolution of lattice constant and SFE. These findings shed light on the deformation mechanism of the alloys with different compositions.

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    Robust ultrathin and transparent AZO/Ag-SnOx/AZO on polyimide substrate for flexible thin film heater with temperature over 400 °C
    Zhaozhao Wang, Jia Li, Junjun Xu, Jinhua Huang, Ye Yang, Ruiqin Tan, Guofei Chen, Xingzhong Fang, Yue Zhao, Weijie Song
    J. Mater. Sci. Technol., 2020, 48 (0): 156-162.  DOI: 10.1016/j.jmst.2020.01.058
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    We developed flexible and transparent thin film heaters (TFHs) with a structure of AZO/Ag-SnOx/AZO/polyimide (PI) which exhibited superior stability under operational conditions. Ultrathin and robust doped silver (Ag) films were produced by introducing a small amount of SnOx during the sputtering process. The AZO/Ag-SnOx/AZO stacks showed the best figure of merit value of 139.9, which was higher than that of ITO counterpart (25.5) with the same thickness. In addition, it exhibited excellent durability, which showed unaffected optical and electrical properties under the heat treatment of 500 °C for 30 min in air, highly-accelerated temperature and humidity stress test (HAST) at 121 °C and 97%RH for 36 h, 10,000 times of scratching and 1500 times of inner and outer bending test. Furthermore, the TFHs based on AZO/Ag-SnOx/AZO/PI achieved a high temperature of 438.8 °C with response time in several seconds, which outperformed most previous studies. The robust high-temperature TFHs in this research hold promising commercial applications in flexible and high temperature occasions.

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    A novel computational framework for establishment of atomic mobility database directly from composition profiles and its uncertainty quantification
    Jing Zhong, Lijun Zhang, Xiaoke Wu, Li Chen, Chunming Deng
    J. Mater. Sci. Technol., 2020, 48 (0): 163-174.  DOI: 10.1016/j.jmst.2019.12.038
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    In this work, a novel computational framework for establishment of atomic mobility database directly from the experimental composition profiles and its uncertainty quantification was developed by merging the Bayesian inference with the Markov chain Monte Carlo algorithm into the latest version of the HitDIC software. By treating the simulation of composition profiles with the composition-dependent coefficients as the forward problem, the inverse coefficient problem that provides the potential way to compute the atomic mobilities directly from composition profiles can be postulated. The values and uncertainties of the atomic mobility parameters of interest were assessed by means of Bayesian inference, where the composition profiles were consumed directly. Benchmark tests that consider the number of diffusion couples and the noise levels were conducted. Practical application of the current framework in determination of atomic mobility descriptions of fcc Ni-Ta and Ni-Al-Ta alloys was performed. Further discussion about the results of the benchmark tests and practical study case indicated that the present computational framework together with numbers of composition profiles from the multiple diffusion couples can help to establish the high-quality atomic mobility database of the target multicomponent alloys.

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    Unique microstructure and thermal insulation property of a novel waste-utilized foam ceramic
    F.H. Kuang, S.M. Wang, C. Gao, H.B. Zhang, R.K. Ren, J.L. Ren, J. Tong, Y.M. Liu, J. Liu
    J. Mater. Sci. Technol., 2020, 48 (0): 175-179.  DOI: 10.1016/j.jmst.2020.03.017
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    A characteristic CaO-Al2O3-SiO2 based foam ceramic was prepared by melt-foaming with solid wastes as main raw materials. The similarity to sandwich hole wall microstructure of this novel thermal insulating material was presented and the relationships between this unique microstructure and porosity, density, thermal conductivity and strength were discussed. Comparing the measured and theoretical values with that of the traditional foam ceramic, it can be found that, for the matching of fine skeleton with hole wall, this original sandwich structure can reduce thermal conductivity and increase flexural strength effectively.

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    Laser ablation and structuring of CdZnTe with femtosecond laser pulses
    J.J.J. Nivas, E. Allahyari, A. Vecchione, Q. Hao, S. Amoruso, X. Wang
    J. Mater. Sci. Technol., 2020, 48 (0): 180-185.  DOI: 10.1016/j.jmst.2020.01.059
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    We report an experimental investigation on laser ablation and associated surface structuring of CdZnTe by femtosecond Ti:Sa laser pulses (laser wavelength λ≈800 nm, ≈35 fs, 10 Hz), in air. By exploiting different static irradiation conditions, the fluence threshold and the incubation effect in CdZnTe are estimated. Interestingly, surface treatment with a low laser fluence (laser pulse energy E≈5-10 μJ) and number of shots (5≤ N ≤50) show the formation of well-defined cracks in the central part of the shallow crater, which is likely associated to a different thermal expansion coefficients of Te inclusions and matrix during the sample heating and cooling processes ensuing femtosecond laser irradiation. Irradiation with a larger number of pulses (N≈500, 1000) with higher pulse energies (E≈30-50 μJ) results in the formation of well-defined laser-induced periodic surface structures (LIPSS) in the outskirts of the main crater, where the local fluence is well below the material ablation threshold. Both low spatial frequency and high spatial frequency LIPSS perpendicular to the laser polarization are found together and separately depending on the irradiation condition. These are ascribed to a process of progressive aggregation of randomly distributed nanoparticles produced during laser ablation of the deep crater in the region of the target irradiated by a fluence below the ablation threshold with many laser pulses.

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    In-situ ZrB2- hBN ceramics with high strength and low elasticity
    Ji Zou, Guo-Jun Zhang, Zheng-Yi Fu
    J. Mater. Sci. Technol., 2020, 48 (0): 186-193.  DOI: 10.1016/j.jmst.2020.01.061
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    ZrB2 ceramics with various hexagonal BN (hBN) additions up to 37 vol% were reactively densified by spark plasma sintering using powder mixtures containing ZrB2, ZrN and boron. ZrN-boron based additives effectively promoted the densification process, ZrB2 ceramics reached >99 % relative density at 2000 °C and an applied pressure of 60 MPa with only 5 vol% in-situ formed hBN, whereas the relative density of pure ZrB2 was only 91.2 % at the same conditions. Increasing the hBN contents, the morphology of hBN grains gradually changed from quasi-spherical to flake dominated, which has substantial influence on their mechanical properties. In-situ ZrB2-10 vol% hBN ceramics demonstrated high flexural strength of 597 ± 22 MPa, relatively low Young’s modulus of 406 GPa and good machinability, especially for the impressively large strain to failure (1.47 × 10-3) which is superior to most of their counterparts in the ZrB2 based particulate reinforced ceramics.

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ISSN: 1005-0302
CN: 21-1315/TG
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