Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
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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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Cellular automaton modeling of austenite formation from ferrite plus pearlite microstructures during intercritical annealing of a C-Mn steel
Chunni Jia, Chengwu Zheng, Dianzhong Li
J. Mater. Sci. Technol.    2020, 47 (0): 1-9.   doi:10.1016/j.jmst.2020.02.002
Abstract198)   HTML11)    PDF (4092KB)(50)      

A mesoscopic cellular automaton model was developed to study the microstructure evolution and solute redistribution of austenization during intercritical annealing of a C-Mn steel. This model enables a depiction of three-stage kinetics of the transformation combined with the thermodynamic analysis: (1) the rapid austenite growth accompanied with pearlite degeneration until the pearlite dissolves completely; (2) the slower austenite growth into ferrite with a rate limiting factor of carbon diffusion in austenite; and (3) the slow austenite growth in control of the manganese diffusion until the final equilibrium reached for ferrite and austenite. The effect of the annealing temperature on the transformation kinetics and solute partition is also quantitatively rationalized using this model.

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Synthesis and photocatalytic performance of ZnO with flower-like structure from zinc oxide ore
Xiaoyi Shen, Hongmei Shao, Yan Liu, Yuchun Zhai
J. Mater. Sci. Technol.    2020, 51 (0): 1-7.   doi:10.1016/j.jmst.2020.01.062
Abstract197)   HTML14)    PDF (2989KB)(104)      

AAAAAEmploying zinc sulfate solution obtained from zinc oxide ore as raw material, sodium hydroxide as precipitant and PEG20000 as dispersant, ultrafine ZnO powders with different morphologies were successfully synthesized through hydrothermal method. The influences of the dosage of PEG20000 solution, molar ratio of OH -/Zn 2+, reaction temperature, reaction time and Zn 2+ concentration on the structures and morphologies of the ZnO powders were discussed in detail. The reaction conditions of synthesizing ZnO powders with flower-like structure were obtained as below: dosage of PEG20000 with 10% mass fraction 5 mL, molar ratio of OH - to Zn 2+ 5, reaction temperature 150 °C, reaction time 8 h at Zn 2+ concentration 1 mol L -1. The growth mechanism of ZnO particles with different morphologies was proposed. The ZnO powder with flower-like structure are composed of multiple micro-rods with hexagon morphology and has good photocatalytic degradation ability to degrade RhB. 20 mL RhB solution with 15 mg L -1 could be completely degraded over flower-like ZnO powder 300 mg within 3 h.

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Effects of rare earth on microstructure and impact toughness of low alloy Cr-Mo-V steels for hydrogenation reactor vessels
Zhonghua Jiang, Pei Wang, Dianzhong Li, Yiyi Li
J. Mater. Sci. Technol.    2020, 45 (0): 1-14.   doi:10.1016/j.jmst.2019.03.012
Abstract169)   HTML5)    PDF (6541KB)(69)      

The effects of rare earth (RE) on the microstructure and impact toughness of low alloy Cr-Mo-V bainitic steels have been investigated where the steels have RE content of 0 to 0.048 wt.%. The results indicate that the normalized microstructures of the steels are typical granular bainite (GB) composed primarily of bainitic ferrite and martensite and/or austenite (M-A) constituents. The M-A constituents are transformed into ferrite and carbides and/or agglomerated carbides after tempering at 700 °C for 4 h. The addition of RE decreases the onset temperature of bainitic transformation and results in the formation of finer bainitic ferrite, and reduces the amount of carbon-rich M-A constituents. For the normalized and tempered samples, the ductile-to-brittle transition temperature (DBTT) decreases with increasing RE content to a critical value of 0.012 wt.%. Lower DBTT and higher upper shelf energy are attributed to the decreased effective grain size and lower amount of coarse agglomerated carbides from the decomposition of massive M-A constituents. However, the addition of RE in excess of 0.012 wt.% leads to a substantial increase in the volume fraction of large-sized inclusions, which are extremely detrimental to the impact toughness.

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Effects of ultrasonic assisted friction stir welding on flow behavior, microstructure and mechanical properties of 7N01-T4 aluminum alloy joints
Zhiqiang Zhang, Changshu He, Ying Li, Lei Yu, Su Zhao, Xiang Zhao
J. Mater. Sci. Technol.    2020, 43 (0): 1-13.   doi:10.1016/j.jmst.2019.12.007
Abstract167)   HTML5)    PDF (10012KB)(80)      

Conventional friction stir welding (FSW) and ultrasonic assisted friction stir welding (UAFSW) were employed to weld 6-mm thick 7N01-T4 aluminum alloy plates. Weld forming characteristics and material flow behavior in these two different welding processes were studied and compared. Ultrasonic vibration was applied directly on the weld in axial direction through the welding tool. Metal flow behavior, microstructure characteristics in the nugget zone (NZ) and evolution of the mechanical properties of naturally aged joints were studied. Results show that the ultrasonic vibration can significantly increase the welding speed of defect-free welded joint. At the rotation speed of 1200 rpm, the UAFSW can produce defect-free welded joints at a welding speed that is 50% higher than that of the conventional FSW. Ultrasonic vibrations can also improve surface quality of the joints and reduce axial force by 9%. Moreover, ultrasonic vibrations significantly increase the volume of the pin-driven zone (PDZ) and decrease the thickness of the transition zone (TZ). The number of subgrains and deformed grains resulting from the UAFSW is higher than that from the FSW. By increase the strain level and strain gradient in the NZ, the ultrasonic vibrations can refine the grains. Ultrasonic energy is the most at the top of the NZ, and gradually reduces along the thickness of the plate. The difference in strengths between the FSW and the UAFSW joints after post-weld natural aging (PWNA) is small. However, the elongation of the UAFSW is 8.8% higher than that of the FSW (PWNA for 4320 h). Fracture surface observation demonstrates that all the specimens fail by ductile fracture, and the fracture position of the UAFSW joint changes from HAZ (PWNA for 120 h) to NZ (PWNA for 720 and 4320 h).

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Resistive switching performance improvement of InGaZnO-based memory device by nitrogen plasma treatment
Li Zhang, Zhong Xu, Jia Han, Lei Liu, Cong Ye, Yi Zhou, Wen Xiong, Yanxin Liu, Gang He
J. Mater. Sci. Technol.    2020, 49 (0): 1-6.   doi:10.1016/j.jmst.2020.01.049
Abstract156)   HTML10)    PDF (2441KB)(61)      

With the demand of flat panel display development, utilizing the non-volatile memory devices based on indium-gallium-zinc-oxide (IGZO) film may be integrated with IGZO thin film transistors (TFTs) to accomplish system-on-panel applications. In this work, 1 × 1 μm2 via hole structure IGZO based memory device was fabricated and the resistive switching (RS) behavior was investigated. By inserting a nitrogen doping layer IGZO:N by plasma treatment in Pt/IGZO/TiN device, highly improved RS performance including lower forming voltage, remarkable uniformity, large memory window of 102, retention property of 104 s at 125 °C, excellent pulse endurance of 107 cycles were achieved. The X-ray photoelectron spectroscopy analysis indicates that plasma doping method can evenly dope nitrogen and induce more non-lattice oxygen in the IGZO film. It is deduced that the N atoms of the inserting layer can influence the random formation of oxygen vacancy type conducting filaments, which results in more stable and uniform performance.

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Phase-field simulation of early-stage kinetics evolution of γ' phase in medium supersaturation Co-Al-W alloy
Shujing Shi, Zhengwei Yan, Yongsheng Li, Suleman Muhammad, Dong Wang, Shi Chen, Shengshun Jin
J. Mater. Sci. Technol.    2020, 53 (0): 1-12.   doi:10.1016/j.jmst.2020.02.038
Abstract151)   HTML8)    PDF (6244KB)(59)      

The early precipitation of γ'-Co3(Al, W) phase affects the spatial distribution and kinetic evolution of precipitates for the morphology transmission effect, but the nucleation and concomitant growth are not studied still by aging experiments due to the expeditious precipitation of γ' phase in Co-Al-W alloy. By using the phase-field simulation with sublattice free energy, the early-stage kinetics evolution of γ'-Co3(Al, W) phase in a medium supersaturation Co-9Al-8W (at.%) alloy aged from 1023 K to 1173 K is investigated. The influences of aging temperature on the evolution of morphology and composition of γ' phase, and the kinetics of nucleation and growth to coarsening are clarified. It is found that the rates of composition evolution of W in γ phase are two or three times that of γ' phase, and the W compositions in γ and γ' phases show a linear relationship with time t-1/3, which means that the coarsening takes place earlier at high temperature. In addition, the equilibrium partitioning ratios indicate Al and W partition into the γ' phase and the ratios decrease with elevated temperature. The compositional variations across the γ/γ' phase interfaces suggest that low aging temperature makes the stoichiometric ratio closer to 3:1. Moreover, the precipitation evolutions from early nucleation to growth and coarsening in Co-Al-W alloy are distinguished, and the rate constants of square and cube of average particles radius increase with temperature. In later growth stage, the relationship of the square of average particles radius and time is obeyed, while the steady-state coarsening stage follows the cube law. The time exponents of particles number density at the coarsening stage are close to -1 of Kuehmann-Voorhees (KV) theory. The study demonstrates that the early-stage evolution of γ' phase which is undiscovered in the experiment can be captured by the phase-field simulation, and the resultant kinetics laws agree well with the experimental and theoretical results.

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Inhibition effects of benzalkonium chloride on Chlorella vulgaris induced corrosion of carbon steel
Junlei Wang, Tiansui Zhang, Xinxin Zhang, Muhammed Asif, Lipei Jiang, Shuang Dong, Tingyue Gu, Hongfang Liu
J. Mater. Sci. Technol.    2020, 43 (0): 14-20.   doi:10.1016/j.jmst.2020.01.012
Abstract120)   HTML2)    PDF (2654KB)(33)      

In this work, a surfactant, benzalkonium chloride (BAC), was used to study its effects on both the growth of Chlorella vulgaris and the corrosion caused by its biofilm. Experimental results indicated that BAC at a low concentration of 3 mg/L suppressed C. vulgaris growth and achieved 81 % corrosion inhibition based on weight loss reduction. The inhibition effects increased when the BAC dosage was increased. At 30 mg/L, the corrosion inhibition increased to 95 %. Electrochemical results supported surface pitting analysis, weight loss results data and confirmed the corrosion inhibition.

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Comparative study of performance comparison of AlSi10Mg alloy prepared by selective laser melting and casting
Qian Yan, Bo Song, Yusheng Shi
J. Mater. Sci. Technol.    2020, 41 (0): 199-208.   doi:10.1016/j.jmst.2019.08.049
Abstract109)   HTML3)    PDF (4987KB)(40)      

The influence of the microstructure on mechanical properties of AlSi10Mg fabricated by casting and selective laser melting (SLM) were investigated and contrasted in this work, with an emphasis on understanding the forming mechanism. The microstructure, phase structure and mechanical properties were characterized by scanning electron microscopy/field-emission Transmission Electron Microscopy (SEM/TEM), X-Ray Diffraction (XRD), tensile and fatigue tests. The results indicated that the SLM AlSi10Mg exhibited a supersaturated Si network structure precipitated along α-Al cell. Brittle β-Al5FeSi and π-Al8FeMg3Si6 phases were found in the as-cast and SLM AlSi10Mg respectively due to different thermal histories during processing. The SLM AlSi10Mg showed higher tensile strength but lower elongation than the casting, as the result of grain refinement and tortuous crack path. The fatigue results revealed that unmelted powder, oxide inclusion and pores can considerably degrade the fatigue properties for the SLM AlSi10Mg. The SLM process offered a new method for material processing that would avoid harmful Fe-bearing intermetallic compounds and refine the microstructures for enhancing strength.

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Design and development of a high-performance Ni-based superalloy WSU 150 for additive manufacturing
Praveen Sreeramagiri, Ajay Bhagavatam, Abhishek Ramakrishnan, Husam Alrehaili, Guru Prasad Dinda
J. Mater. Sci. Technol.    2020, 47 (0): 20-28.   doi:10.1016/j.jmst.2020.01.041
Abstract107)   HTML5)    PDF (4460KB)(34)      

This research proposes a design and development strategy of a new nickel-based superalloy for additive manufacturing. A new Ni-based superalloy has been developed by the application of the combinatorial alloy development technique coupled with CALPHAD based solidification modeling by effectively suppressing the precipitation kinetics. The suppression of precipitation during processing paved a way for prevention of cracks during deposition. The new alloy “WSU 150″ revealed excellent room temperature mechanical properties with a yield strength of 867 MPa, an ultimate tensile strength of 1188 MPa, and an elongation of 27.9% in the as-deposited condition. The mechanical properties of the heat-treated alloy were improved significantly to 1114 MPa yield strength, 1396 MPa ultimate tensile strength, and an elongation of 16.1%. Improvement in the mechanical properties is attributed to the additional precipitation and coarsening of γ' and carbides during heat-treatment. Microstructural investigation of the alloy revealed spherical γ' with a rippled size distribution from the center to the interdendritic region. The average size of the γ' particles in the as-deposited condition was found to be around 48 nm in the interdendritic region. Heat-treatment promoted the coarsening of γ' which is explained in the paper.

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Microstructure and mechanical properties of (TiZrNbTaMo)C high-entropy ceramic
Kai Wang, Lei Chen, Chenguang Xu, Wen Zhang, Zhanguo Liu, Yujin Wang, Jiahu Ouyang, Xinghong Zhang, Yudong Fu, Yu Zhou
J. Mater. Sci. Technol.    2020, 39 (0): 99-105.   doi:10.1016/j.jmst.2019.07.056
Abstract105)   HTML0)    PDF (3451KB)(100)      

A high-entropy (TiZrNbTaMo)C ceramic has been successfully fabricated by hot pressing the newly-synthesized quinary carbide powder to investigate its microstructure and mechanical properties. The carbothermal reduction process of equimolar quinary metallic oxides at 1500 ℃ for 1 h generates a carbide powder mixture, which consists mainly of TaC- and ZrC-based solid solutions. The as-synthesized powder was then sintered to form a single-phase high-entropy ceramic by a two-step hot pressing at 1850 ℃ for 1 h and 2100 ℃ for 0.5 h, respectively. The high-entropy ceramic exhibits a fine grain size of about 8.8 μm, a high compositional uniformity and a high relative density of 98.6% by adding Mo as the strategic main component. The measured nanohardness values of (TiZrNbTaMo)C ceramic are 25.3 GPa at 9.8 N and 31.3 GPa at 100 mN, respectively, which are clearly higher than those of other available high-entropy carbide ceramics.

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Microbiologically influenced corrosion of Cu by nitrate reducing marine bacterium Pseudomonas aeruginosa
Yanan Pu, Wenwen Dou, Tingyue Gu, Shiya Tang, Xiaomei Han, Shougang Chen
J. Mater. Sci. Technol.    2020, 47 (0): 10-19.   doi:10.1016/j.jmst.2020.02.008
Abstract103)   HTML5)    PDF (4583KB)(29)      

The microbiologically influenced corrosion (MIC) mechanisms of copper by Pseudomonas aeruginosa as a typical strain of nitrate reducing bacteria (NRB) was investigated in this lab study. Cu was immersed in deoxygenated LB-NO3 seawater inoculated with P. aeruginosa and incubated for 2 weeks. Results showed that this NRB caused pitting and uniform corrosion. The maximum pit depths after 7 d and 14 d in 125 mL anaerobic vials with 50 mL broth were 5.1 μm and 9.1 μm, accompanied by specific weight losses of 1.3 mg/cm2 (7 d) and 1.7 mg/cm2 (14 d), respectively. Electrochemical measurements corroborated weight loss and pit depth data trends. Experimental results indicated that extracellular electron transfer for nitrate reduction was the main MIC mechanism and ammonia secreted by P. aeruginosa could also play a role in the overall Cu corrosion process.

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New FeNiCrMo(P, C, B) high-entropy bulk metallic glasses with unusual thermal stability and corrosion resistance
Yanhui Li, Siwen Wang, Xuewei Wang, Meiling Yin, Wei Zhang
J. Mater. Sci. Technol.    2020, 43 (0): 32-39.   doi:10.1016/j.jmst.2020.01.020
Abstract101)   HTML0)    PDF (5137KB)(36)      

New Fe20-35Ni20Cr20-30Mo5-15(P0.6C0.2B0.2)20 bulk metallic glasses with excellent thermal stability, strength, and corrosion resistance have been developed through the high-entropy alloy design strategy. The high-entropy bulk metallic glasses (HE-BMGs) possess larger supercooled liquid regions of ~69 K, higher crystallization onset temperatures of ~852 K, larger undercoolings of ~109 K, and more sluggish crystallization process upon heating than the conventional metallic glass benefited from the high mixing entropy effect. The HE-BMGs also exhibit ultrahigh strength of ~3.4 GPa, Vickers hardness of ~1107, and superior corrosion resistance in acids and NaCl solutions by formation of highly stable Cr- and Mo-enriched passive films. The new metal-metalloid HE-BMG system and exceptional properties give the alloys good promise for both scientific and engineering applications.

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Nanoporous Au-Sn with solute strain for simultaneously enhanced selectivity and durability during electrochemical CO2 reduction
Xianglong Lu, Tianshui Yu, Hailing Wang, Lihua Qian, Ruichun Luo, Pan Liu, Yao Yu, Lin Liu, Pengxiang Lei, Songliu Yuan
J. Mater. Sci. Technol.    2020, 43 (0): 154-160.   doi:10.1016/j.jmst.2019.11.007
Abstract99)   HTML0)    PDF (2155KB)(20)      

Electrochemical carbon dioxide reduction meditated by metallic catalysts suffers from restricted selectivity and competition from hydrogen evolution, which sensitively depends on ambiguous contributions of alloying and strain state in bimetallic catalysts. Herein, nanoporous Au-Sn (NPAS) containing trace tin solute in Au lattices is delicately designed to convince real strain effect, while eliminating other undesirable factors, such as alloying, crystal facets and surface composition. Compared with nanoporous gold (NPG), the NPAS with a solute strain of ~2.2 % enables more efficient CO2-to-CO conversion, with an efficiency as high as 92 % at -0.85 V versus reversible hydrogen electrode (vs. RHE), and the high activity can retain for more than 8 h. The combination of HRTEM and surface valence band photoemission spectra reveals that the tensile strain on the surface of 3D nanoporous structure promotes the catalytic activity by shifting up the d-band center and strengthening the adsorption of key intermediate *COOH. A small amount of Sn solute in the nanoporous alloy can prevent ligament coarsening effectively and improve the electrochemical stability.

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High strength and ductility Mg-8Gd-3Y-0.5Zr alloy with bimodal structure and nano-precipitates
Xiaoxiao Wei, Li Jin, Fenghua Wang, Jing Li, Nan Ye, Zhenyan Zhang, Jie Dong
J. Mater. Sci. Technol.    2020, 44 (0): 19-23.   doi:10.1016/j.jmst.2019.10.024
Abstract99)   HTML5)    PDF (2424KB)(29)      

To resolve the strength-ductility trade-off problem for high-strength Mg alloys, we prepared a high performance Mg-8Gd-3Y-0.5 Zr (wt%) alloy with yield strength of 371 MPa, ultimate tensile strength of 419 MPa and elongation of 15.8%. The processing route involves extrusion, pre-deformation and aging, which leads to a bimodal structure and nano-precipitates. Back-stress originated from the deformation-incompatibility in the bimodal-structure alloy can improve ductility. In addition, dislocation density in coarse grains increased during the pre-deformation strain of 2%, and the dislocations in coarse grains can promote the formation of chain-like nano-precipitates during aging treatment. The chain-like nano-precipitates can act as barriers for dislocations slip and the existing mobile dislocations enable good ductility.

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(Y0.25Yb0.25Er0.25Lu0.25)2(Zr0.5Hf0.5)2O7: A defective fluorite structured high entropy ceramic with low thermal conductivity and close thermal expansion coefficient to Al2O3
Zifan Zhao, Heng Chen, Huimin Xiang, Fu-Zhi Dai, Xiaohui Wang, Wei Xu, Kuang Sun, Zhijian Peng, Yanchun Zhou
J. Mater. Sci. Technol.    2020, 39 (0): 167-172.   doi:10.1016/j.jmst.2019.08.018
Abstract98)   HTML3)    PDF (2590KB)(50)      
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Progress in achieving high-performance piezoresistive and capacitive flexible pressure sensors: A review
Wufan Chen, Xin Yan
J. Mater. Sci. Technol.    2020, 43 (0): 175-188.   doi:10.1016/j.jmst.2019.11.010
Abstract98)   HTML2)    PDF (4683KB)(36)      

Electronic skin (e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin (e-skin) into true "skin" is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years, including numerous studies on improving sensor performance, and in particular, sensitivity. In addition, a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here, we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.

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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
Abstract98)   HTML2)    PDF (3956KB)(44)      

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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Microstructure and tensile properties of DD32 single crystal Ni-base superalloy repaired by laser metal forming
Shiwei Ci, Jingjing Liang, Jinguo Li, Yizhou Zhou, Xiaofeng Sun
J. Mater. Sci. Technol.    2020, 45 (0): 23-34.   doi:10.1016/j.jmst.2020.01.003
Abstract96)   HTML5)    PDF (7715KB)(36)      

In this work, the microstructure and tensile properties of DD32 single-crystal (SC) superalloy repaired by laser metal forming (LMF) using pulsed laser have been studied in detail. The microstructures of the deposited samples and the tensile-ruptured samples were characterized by optical microscopy (OM), transmission electron microscope (TEM) and scanning electron microscope (SEM). Due to high cooling rate, the primary dendrite spacing in the deposited area (17.2 μm) was apparently smaller than that in the substrate area (307 μm), and the carbides in the deposited samples were also smaller compared with that in the substrate area. The formation of (γ+γ′) eutectic in the initial layer of repaired SC was inhibited because of the high cooling rate. As the deposition proceeded, the cooling rate decreased, and the (γ+γ′) eutectic increased gradually. The (γ+γ′) eutectic at heat-affected zone (HAZ) in the molten pool dissolved partly because of the high temperature at HAZ, but there were still residual eutectics. Tensile test results showed that tensile behavior of repaired SC at different temperatures was closely related to the MC carbides, solidification porosity, γ′ phase, and (γ+γ′) eutectic. At moderate temperature, the samples tested fractured preferentially at the substrate area due to the fragmentation of the coarse MC carbide in the substrate area. At elevated temperature, the (γ+γ′) eutectic and solidification porosity in the deposited area became the source of cracks, which deteriorated the high-temperature properties and made the samples rupture at the deposited area preferentially.

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Zwitterionic glycine modified Fe/Mg-layered double hydroxides for highly selective and efficient removal of oxyanions from polluted water
Xiaofeng Shi, Chao Wang, Jiaoxia Zhang, Li Guo, Jing Lin, Duo Pan, Juying Zhou, Jincheng Fan, Tao Ding, Zhanhu Guo
J. Mater. Sci. Technol.    2020, 51 (0): 8-15.   doi:10.1016/j.jmst.2019.12.034
Abstract95)   HTML6)    PDF (2345KB)(36)      

Zwitterionic glycine was employed to modify Fe/Mg-layered double hydroxides (LDH) to realize an G-Fe/Mg-LDH adsorbent with high adsorption capacities of oxygen-containing anions including As(V), P(V) and Cr(VI). When the Fe/Mg mole ratio was 0.02 mol/0.02 mol, the G-Fe/Mg-LDH has a good adsorption performance. The optimum adsorption pH value of G-Fe/Mg-LDH for oxygen-containing anions was 6. The selectivity of three oxygen-containing anions was Cr(VI)<P(V)<As(V), and the maximum adsorption capacity of As(V) reached as high as 830 mg g -1, outperforming most previously reported efficient adsorbents for As(V). The adsorption process followed Freundlich isotherm and pseudo-second-order kinetic model, suggesting the heterogeneous adsorption and chemical adsorption of the G-Fe/Mg-LDH. When the initial concentration of As(V) was 200 mg L -1, the adsorption efficiency of G-Fe/Mg-LDH was 82.5% within 30 min. This study provides a way to modify the LDHs for environmental remediation.

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Phosphide-oxide honeycomb-like heterostructure CoP@CoMoO4/CC for enhanced hydrogen evolution reaction in alkaline solution
Zheng Liu, Jieqiong Wang, Changhong Zhan, Jing Yu, Yang Cao, Jinchun Tu, Changsheng Shi
J. Mater. Sci. Technol.    2020, 46 (0): 177-184.   doi:10.1016/j.jmst.2019.12.013
Abstract95)   HTML5)    PDF (3490KB)(13)      

The design and construction of effective and stable hydrogen evolution reaction (HER) catalysts represent the key to obtaining hydrogen energy economically. Transition metal phosphides (TMPs) have attracted considerable attention due to their unique catalytic mechanism, which is similar to hydrogenase. However, single-phase TMPs remain limited by their low activity and weak stability in alkaline solutions. In this work, CoP@CoMoO4 nanosheets with phosphide and oxide heterostructure were synthesized on carbon cloth (CC) through hydrothermal method and subsequently reacted with red phosphorus in a tube furnace. The outstanding synergy between CoP and CoMoO4 enhanced the HER activity and stability in alkaline solution. The CoP@CoMoO4/CC heterostructure exhibited excellent HER activity with a low overpotential of 89 mV at 10 mA cm-2 with Tafel slope of 69 mV dec-1, and outstanding stability when compared with single-phase phosphides. Our present research provides a new approach for the preparation of inexpensive, highly active, and highly durable phosphorus-based catalyst for HER.

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Probing martensitic transformation, kinetics, elastic and magnetic properties of Ni2-xMn1.5In0.5Cox alloys
Xinzeng Liang, Jing Bai, Jianglong Gu, Haile Yan, Yudong Zhang, Claude Esling, Xiang Zhao, Liang Zuo
J. Mater. Sci. Technol.    2020, 44 (0): 31-41.   doi:10.1016/j.jmst.2020.01.034
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The martensitic transformation, kinetics, elastic and magnetic properties of the Ni2-xMn1.5In0.5Cox (x = 0-0.33) ferromagnetic shape memory alloys were investigated experimentally and theoretically by first-principles calculations. First-principles calculations show that Co directly occupies the site of Ni sublattice, and Co atoms prefer to distribute evenly in the structure. The optimized lattice constants are consistent with the experimental results. The martensitic transformation paths are as follows: PA ↔ FA ↔ 6 MFIM ↔ NMFIM when 0 ≤ x < 0.25; PA ↔ FA ↔ 6 MFM ↔ NMFIM with 0.25 ≤ x < 0.3 and PA ↔ FA ↔ NMFM with 0.3 ≤ x ≤ 0.33 for Ni2-xMn1.5In0.5Cox (x = 0-0.33) alloys. The fundamental reasons for the decrease of TM with increasing Co content are explained from the aspects of first-principles calculations and martensitic transformation kinetics. The component interval of the magnetostructural coupling is determined as 0 ≤ x ≤ 0.25 by first-principles calculations. Furthermore, the origin of the demagnetization effect during martensitic transformation is attributed to the shortening of the nearest neighboring distances for Ni-Ni (Co) and Mn-Mn. Combining the theoretical calculations with experimental results, it is verified that the TM of the Co6 alloy is near room temperature and its magnetization difference ΔM is 94.6 emu/g. Therefore, magnetic materials with high performance can be obtained, which may be useful for new magnetic applications.

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Ultrafast synthesis of gold nanoparticles on cellulose nanocrystals via microwave irradiation and their dyes-degradation catalytic activity
Madhusudhan Alle, Seung-Hwan Lee, Jin-Chul Kim
J. Mater. Sci. Technol.    2020, 41 (0): 168-177.   doi:10.1016/j.jmst.2019.11.003
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This study represents a well-dispersed gold nanoparticles (AuNPs) synthesis process via cellulose nanocrystals (CNC) which acts as both reducing and supporting agent. The synthesis process was ultrafast and completed in a few seconds using microwave irradiation. The entire synthesis process was cost-effective, sustainable and eco-friendly. The synthesized (AuNPs/CNC) nanocomposite was investigated by transmission electron microscopy, selected area electron diffraction, Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, X-ray diffraction, and UV-vis spectroscopy. The obtained AuNPs were well accumulated on the CNC surface and had a uniform spherical shape with an average diameter of 8 ± 5.3 nm. The diameter of AuNPs could be altered by tuning the concentration of CNC suspension. The synthesized AuNPs/CNC nanocomposite film exhibited excellent degradation properties against various organic dyes, namely, Allura red, Congo red, Rhodamine B and Amaranth. The ultrafast degradation reactions followed pseudo first order kinetics. In the catalytic degradation reaction, AuNPs/CNC was transmitting electrons from a donor (NaBH4) to an acceptor (a dye).

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Evaluation of the inhibition behavior of carbon dots on carbon steel in HCl and NaCl solutions
Yuwei Ye, Zilong Jiang, Yangjun Zou, Hao Chen, Shengda Guo, Qiumin Yang, Liyong Chen
J. Mater. Sci. Technol.    2020, 43 (0): 144-153.   doi:10.1016/j.jmst.2020.01.025
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An eco-friendly and effective corrosion inhibitor (N-CDs) was acquired by hydrothermal method in methacrylic acid and ethyl(methyl)amine precursors. Afterwards, the weight loss and electrochemistry measurement were chosen to appraise the corrosion inhibition behavior of as-prepared N-CDs for Q235 steel in Cl- contained solutions. The change rules of EIS and Tafel data displayed that the as-prepared N-CDs revealed a high-efficiency protection for steel in all test environments. Meanwhile, the inhibition efficiency of steel reached up to 93.93 % (1 M HCl) and 88.96 % (3.5 wt% NaCl) at 200 mg/L of N-CDs. Furthermore, the N-CDs could form the adsorption film on steel surface to avoid the strong attack of Cl-. By analysis, the adsorption mechanism of as-prepared N-CDs on steel surface was physicochemical interaction, which strictly complied with the Langmuir adsorption model in both solutions.

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Cracking behavior and control of β-solidifying Ti-40Al-9V-0.5Y alloy produced by selective laser melting
Piao Gao, Wenpu Huang, Huihui Yang, Guanyi Jing, Qi Liu, Guoqing Wang, Zemin Wang, Xiaoyan Zeng
J. Mater. Sci. Technol.    2020, 39 (0): 144-154.   doi:10.1016/j.jmst.2019.08.026
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A β-solidifying Ti-40Al-9V-0.5Y (at.%) alloy with a high cracking sensitivity has been successfully fabricated by selective laser melting (SLM) in this study. The influence factors for cracking sensitivity, cracking behavior and crack inhibition mechanism were investigated. The results show that the effects of process parameters on cracking sensitivity strongly depend on the cooling rate in molten pool with different heat transfer modes. The conduction mode with higher cooling rates exhibits a higher cracking sensitivity in comparison to the keyhole mode. Microstructure characteristics and phase transformations controlled by cooling rate determine the inherent ductility of β-solidifying γ-TiAl alloys during SLM. On this basis, the formation and inhibition mechanism of solidification and cold cracking are proposed. Finally, the crack-free Ti-40Al-9V-0.5Y sample with fine equiaxed microstructures and favorable mechanical properties (microhardness of 542 ± 19 HV, yield strength of 1871 ± 12 MPa, ultimate strength of 2106 ± 13 MPa and ultimate compressive strain of 10.89 ± 0.57%) can be produced by SLM. The strengthening mechanism can be attributed to grain refinement and precipitation strengthening.

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Large electric field-induced strain in the novel BNKTAN-BNBLTZ lead-free ceramics
Chao Wang, Qiang Li, Weiming Zhang, Huiqing Fan
J. Mater. Sci. Technol.    2020, 45 (0): 15-22.   doi:10.1016/j.jmst.2019.09.040
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(1-x)Bi0.5(Na0.82K0.18)0.5Ti0.96(Al0.5Nb0.5)0.04O3-xBi0.46Na0.46Ba0.5La0.02Ti0.97Zr0.03O3 lead-free ceramics (abbreviated as BNKTAN-100xBNBLTZ) was prepared by the conventional solid reaction. XRD patterns and EDS spectrums revealed that a stable solid solution had been formed between BNBLTZ and BNKTAN. With the introduction of BNBLTZ anti-ferroelectric content, BNKTAN relaxor ferroelectrics exhibited the excellent field-induced-strain for x = 0.04 corresponding to electric field-induced strain S ~ 0.505 % and normal strain d33* ~777 pm/V at 65 kV/cm. The large strain response was attributed to the emergence of PNRs in the relaxation process. Additionally, an excellent fatigue resistance performance was obtained within 105 cycles (S = 0.505 %-0.495 % and d33* = 777-758 pm/V, 65 kV/cm). It suggested that prepared ceramics had the great potential to strain sensor and actuators.

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Construction of nickel cobalt sulfide nanosheet arrays on carbon cloth for performance-enhanced supercapacitor
Tao Liu, Jiahao Liu, Liuyang Zhang, Bei Cheng, Jiaguo Yu
J. Mater. Sci. Technol.    2020, 47 (0): 113-121.   doi:10.1016/j.jmst.2019.12.027
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Materials featured with self-supported three-dimensional network, hierarchical pores and rich electrochemical active sites are considered as promising electrodes for pseudocapacitors. Herein, a novel strategy for the growth of nickel-cobalt bisulfide (NiCoS) nanosheets arrays on carbon cloth (CC) as supercapacitor electrodes is reported, involving deposition of two-dimensional metal-organic framework (MOF) precursors on the CC skeletons, conversion of MOF into nickel-cobalt layered double-hydroxide by ion exchange process and formation of NiCoS by a sulfidation treatment. The NiCoS nanosheets with rough surface and porous structures are uniformly anchored on the CC skeletons. The unique architecture endows the composite (NiCoS/CC) with abundant accessible active sites. Besides, robust electrical/mechanical joint between the nanosheets and the substrates is attained, leading to the improved electrochemical performance. Moreover, an asymmetric supercapacitor device is constructed by using NiCoS/CC and activated carbon as a positive electrode and a negative electrode, respectively. The optimized device exhibits a high specific capacitance, large energy density and long cycle life. The NiCoS/CC electrode with intriguing electrochemical properties and mechanical flexibility holds great prospect for next-generation wearable devices.

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Fabricating CoCrFeMnNi high entropy alloy via selective laser melting in-situ alloying
Peng Chen, Sheng Li, Yinghao Zhou, Ming Yan, Moataz M. Attallah
J. Mater. Sci. Technol.    2020, 43 (0): 40-43.   doi:10.1016/j.jmst.2020.01.002
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Quasi-equiatomic CoCrFeMnNi high entropy alloy (HEA) has been in-situ alloyed by selective laser melting (SLM) from a blend of CoCrFeNi pre-alloyed powder and Mn elemental powder. The blended powder shows good printability with various SLM parameters and the as-built HEA samples achieve a reliable forming quality. Despite the slight evaporation of Mn, energy dispersive spectrometer mapping and X-ray diffraction results show that the as-built HEA has a homogeneous chemical distribution and presents a single face-centred-cubic (fcc) phase, indicating successful in-situ alloying. The study has verified the feasibility of using blended powder to prepare high-quality HEA by SLM.

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Theoretical prediction on thermal and mechanical properties of high entropy (Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)C by deep learning potential
Fu-Zhi Dai, Bo Wen, Yinjie Sun, Huimin Xiang, Yanchun Zhou
J. Mater. Sci. Technol.    2020, 43 (0): 168-174.   doi:10.1016/j.jmst.2020.01.005
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High entropy materials (HEMs, e.g. high entropy alloys, high entropy ceramics) have gained increasing interests due to the possibility that they can provide challenge properties unattainable by traditional materials. Though a large number of HEMs have emerged, there is still in lack of theoretical predictions and simulations on HEMs, which is probably caused by the chemical complexity of HEMs. In this work, we demonstrate that the machine learning potentials developed in recent years can overcome the complexity of HEMs, and serve as powerful theoretical tools to simulate HEMs. A deep learning potential (DLP) for high entropy (Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)C is fitted with the prediction error in energy and force being 9.4 meV/atom and 217 meV/Å, respectively. The reliability and generality of the DLP are affirmed, since it can accurately predict lattice parameters and elastic constants of mono-phase carbides TMC (TM = Ti, Zr, Hf, Nb and Ta). Lattice constants (increase from 4.5707 Å to 4.6727 Å), thermal expansion coefficients (increase from 7.85×10-6 K-1 to 10.58×10-6 K-1), phonon thermal conductivities (decrease from 2.02 W·m-1·K-1 to 0.95 W·m-1·K-1), and elastic properties of high entropy (Zr0.2Hf0.2Ti0.2Nb0.2Ta0.2)C in temperature ranging from 0 °C to 2400 °C are predicted by molecular dynamics simulations. The predicted room temperature properties agree well with experimental measurements, indicating the high accuracy of the DLP. With introducing of machine learning potentials, many problems that are intractable by traditional methods can be handled now. It is hopeful that deep insight into HEMs can be obtained in the future by such powerful methods.

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Evolution of rust layers on carbon steel and weathering steel in high humidity and heat marine atmospheric corrosion
Yueming Fan, Wei Liu, Shimin Li, Thee Chowwanonthapunya, Banthukul Wongpat, Yonggang Zhao, Baojun Dong, Tianyi Zhang, Xiaogang Li
J. Mater. Sci. Technol.    2020, 39 (0): 190-199.   doi:10.1016/j.jmst.2019.07.054
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The evolution of the rust layers on carbon steel and weathering steel in high humidity and heat marine atmospheric environment was investigated by wet/dry cyclic acceleration corrosion tests in this study. The corrosion process of carbon steel and weathering steel was divided into two stages and the reasons for the changes in the corrosion rates of two steels were different. The composition phase of the inner rust layer of weathering steel was mainly goethite, whereas that of carbon steel was mainly akaganeite. Rust resistance (Rr) performed better than charge transfer resistance (Rt) in evaluating the protection performance of rust layer. As the corrosion proceeded, the evolution of the cathodic process of weathering steel was not obvious, whereas that of carbon steel was irregular.

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Microstructure and fatigue behavior of laser-powder bed fusion austenitic stainless steel
Chenfan Yu, Peng Zhang, Zhefeng Zhang, Wei Liu
J. Mater. Sci. Technol.    2020, 46 (0): 191-200.   doi:10.1016/j.jmst.2019.08.047
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The microstructures and stress-controlled fatigue behavior of austenitic stainless steel (AISI 316 L stainless steel) fabricated via laser-powder bed fusion (L-PBF) technique were investigated. For L-PBF process, zigzag laser scanning strategy (scan rotation between successive layer was 0°, ZZ sample) and cross-hatching layer scanning strategy (scan rotation between successive layer was 67°, CH sample) were employed. By inducing different thermal history, it is found that the scan strategies of laser beam have a significant impact on grain size and morphology. Fatigue cracks generally initiated from persistent slip bands (PSBs) or grain boundaries (GBs). It is observed that PSBs could transfer the melt pool boundaries (MPBs) continuously. The MPBs have better strain compatibility compared with grain boundaries (GBs), thus MPBs would not be the initiation site of fatigue cracks. A higher fatigue limit strength could be achieved by employing a crosshatching scanning strategy. For the CH sample, fatigue cracks also initiated from GBs and PSBs. However, fatigue crack initiated from process-induced defects were observed in ZZ sample in high-cycle regions. Solidification microstructures and defects characteristics are important factors affecting the fatigue performance of L-PBF 316 L stainless. Process-induced defects originated from fluid instability can be effectively reduced by adjusting the laser scan strategy.

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