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.

Current Issue
 15 April 2020, Volume 43 Issue 0 Previous Issue    Next Issue
Research Article
 Select 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 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).
 Select 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 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.
 Select A strategy for designing stable nanocrystalline alloys by thermo-kinetic synergy H.R. Peng, B.S Liu, F. Liu J. Mater. Sci. Technol., 2020, 43 (0): 21-31.  DOI: 10.1016/j.jmst.2019.11.006 Aiming to design stable nanocrystalline (NC) materials, so far, it has been proposed to construct nanostructure stability maps in terms of thermodynamic parameters, while kinetic stabilization has seldom been considered, despite the synergy of thermodynamics and kinetics. Consequently, the thermodynamically stabilized NC materials may be easily subjected to grain growth at high temperatures due to the weakly kinetic stabilization. Starting from the thermo-kinetic synergy, a stabilization criterion is proposed as a function of intrinsic solute parameters (e.g. the activation energy for bulk diffusion and the segregation enthalpy), intrinsic solvent parameters (e.g. the intrinsic activation energy for GB migration and the GB energy) and processing parameters (e.g. the grain size, the temperature and the solute concentration). Using first-principles calculations for a series of combinations between fifty-one substitutional alloying atoms as solute atoms and Fe atom as fixed solvent atom, it is shown that the thermal stability neither simply increases with increasing the segregation enthalpy as expected by thermodynamic stabilization, nor monotonically increases with increasing the activation energy for bulk diffusion as described by kinetic stabilization. By combination of thermodynamic and kinetic contributions, the current stabilization criterion evaluates quantitatively the thermal stability, thus permitting convenient comparisons among NC materials involved by various combinations of the solute atoms, the solvent atoms, or the processing conditions. Validity of this thermo-kinetic stabilization criterion has been tested by current experiment results of Fe-Y alloy and previously published data of Fe-Ni, Fe-Cr, Fe-Zr and Fe-Ag alloys, etc., which opens a new window for designing NC materials with sufficiently high thermal stability and sufficiently small grain size.
 Select 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 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.
 Select 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 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.
 Select Effects of Cu addition on formability and surface delamination phenomenon in high-strength high-Mn steels Jo Min Chul, Jisung Yoo, Jo Min Cheol, Alireza Zargaran, Sohn Seok Su, Kim Nack J., Sunghak Lee J. Mater. Sci. Technol., 2020, 43 (0): 44-51.  DOI: 10.1016/j.jmst.2020.01.021 The formability of austenitic high-Mn steels is a critical issue in automotive applications under non-uniformly-deformed environments caused by dynamic strain aging. Among austenite stabilizing alloying elements in those steels, Cu has been known as an effective element to enhance tensile properties via controlling the stacking fault energy and stability of austenite. The effects of Cu addition on formability, however, have not been sufficiently reported yet. In this study, the Cu addition effects on formability and surface characteristics in the austenitic high-Mn TRIP steels were analyzed in consideration of inhomogeneous microstructures containing the segregation of Mn and Cu. To reveal determining factors, various mechanical parameters such as total elongation, post elongation, strain hardening rate, normal anisotropy, and planar anisotropy were correlated to the hole-expansion and cup-drawing test results. With respect to microstructural parameters, roles of (Mn,Cu)-segregation bands and resultant Cu-rich FCC precipitates on the formability and surface delamination were also discussed.
 Select Novel synthesis method combining a foaming agent with freeze-drying to obtain hybrid highly macroporous bone scaffolds Paulina Kazimierczak, Aleksandra Benko, Krzysztof Palka, Cristina Canal, Dorota Kolodynska, Agata Przekora J. Mater. Sci. Technol., 2020, 43 (0): 52-63.  DOI: 10.1016/j.jmst.2020.01.006 Three-dimensional macroporous scaffolds are commonly used in bone tissue engineering applications since they provide sufficient space for cell migration and proliferation, facilitating bone ingrowth and implant vascularisation. The aim of this work was to combine two simple methods, freeze-drying and gas-foaming, in order to fabricate highly macroporous bone scaffolds made of chitosan/agarose matrix reinforced with nanohydroxyapatite. The secondary goal of this research was to comprehensively assess biomedical potential of developed biomaterials. In this work, it was demonstrated that simultaneous application of freeze-drying and gas-foaming technique allows to obtain hybrid (as proven by ATR-FTIR) macroporous bone scaffolds (pore diameter > 50 μm) characterized by high open (70 %) and interconnected porosity. Novel scaffolds were non-toxic, favoured osteoblasts adhesion and growth and induced apatite formation on their surfaces, indicating their high bioactivity that is essential for good implant osseointegration. Biomaterials were also prone to enzymatic degradation, degradation in acidified microenvironment (e.g. osteoclast-mediated), and slow degradation under physiological pH of 7.4. Moreover, the scaffolds revealed microstructure (70 % open porosity, SSA approx. 30 m2/g, high share of macropores with diameter in the range 100-410 μm) and compressive strength (1-1.4 MPa) comparable to cancellous bone, indicating that they are promising implants for cancellous bone regeneration.
 Select Enhanced oxidation and graphitization resistance of polycrystalline diamond sintered with Ti-coated diamond powders Xiaohua Sha, Wen Yue, Haichao Zhang, Wenbo Qin, Dingshun She, Chengbiao Wang J. Mater. Sci. Technol., 2020, 43 (0): 64-73.  DOI: 10.1016/j.jmst.2020.01.031 To improve the oxidation and graphitization resistances of the polycrystalline diamond (PCD), Ti coating was deposited on the diamond powders via magnetic sputtering method, which achieved a uniform TiC protection barrier in PCD during the sintering process. The phase compositions, microstructures and thermal stability of Ti-PCD were characterized by X-ray diffraction (XRD), Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and thermal gravimetric-differential scanning calorimetry (TG-DSC). The results demonstrate that the oxidation and graphitization resistances of PCD are strengthened due to the existence of TiC phase, which acts as an effective inhibitor. The as-received inhibitor delays the oxidation and graphitization of PCD, elevating their initial temperature by ～50 °C and ～100 °C, respectively. During the annealing treatment of Ti-PCD, the priory oxidation of TiC, which produces TiO2 as an oxygen barrier, postpones the diamond oxide. Moreover, the TiC barrier also protects diamond grains from direct contact with cobalt, thus a lower cobalt-catalytic graphitization, and yields to an improved graphitization resistance of PCD. The enhanced oxidation and graphitization resistances of PCD are of significant importance for practical applications to elevated temperatures.
 Select Effects of yttria content on the CMAS infiltration resistance of yttria stabilized thermal barrier coatings system Chavez Juan J.Gomez, Ravisankar Naraparaju, Peter Mechnich, Klemens Kelm, Uwe Schulz, C.V. Ramana J. Mater. Sci. Technol., 2020, 43 (0): 74-83.  DOI: 10.1016/j.jmst.2019.09.039 The effects of YO1.5 doping in yttria-zirconia based thermal barrier coatings (TBCs) against CMAS interaction/infiltration are discussed. The TBCs with an YO1.5 content ranging from 43-67 mol.% (balance ZrO2) were produced by electron beam physical vapor deposition (EB-PVD) techniques. The results reveal a trend of higher apatite formation probability with the higher free YO1.5 available in the yttria-zirconia system. Additionally, the infiltration resistance and amount of consumed coating appears to be strongly dependent on the YO1.5 content in the coating. The thinnest reaction layer and lowest infiltration was found for the highest produced 67YO1.5 coating. Complementary XRD experiments with volcanic ash/YO1.5 powder mixtures with higher yttria contents than in the coatings (80YO1.5 and pure YO1.5) also showed higher apatite formation with respect to increasing yttria content. The threshold composition to promote apatite-based reaction products was found to be around 50YO1.5 in zirconia which was proved in the coatings and XRD powder experiments. An YO1.5-ZrO2-FeO-TiO2 bearing zirconolite-type phase was formed as a reaction product for all the coating compositions which implicates that TiO2 in the melt acts as a trigger for zirconolite formation. This phase could be detrimental for CMAS/volcanic ash infiltration resistance since it can be formed alongside with apatite which controls or limits the amount of Y3+ available for glass crystallization. The Fe rich garnet phase containing all the possible elements exhibited a slower nucleation compared to apatite and its growth was enhanced with slow cooling rates. The implications of phase stability and heat treatment effects on the reaction products are discussed for tests performed at 1250 °C.
 Select Effects of 1,9-dibromnonane on the structural, photophysical properties and stability of cesium lead bromide perovskite nanocrystals Zhaojun Mo, Qiujie Lu, Zhihong Hao, Zhexuan Zheng, Fu Qiu, Xiao Yang, Zhenyu Li, Lan Li J. Mater. Sci. Technol., 2020, 43 (0): 84-91.  DOI: 10.1016/j.jmst.2019.10.016 The CsPbBr3@Cs4PbBr6 nanocrystals (NCs) could be synthesized by multiple Cs-oleate injections as adding the 1,9-dibromnonane in the reaction solution. The 1,9-dibromnonane could provide Br- ions and the rich Br- ions effectively restrain the generation of CsBr. The Cs4PbBr6 wrapped around the CsPbBr3 NCs and the size of crystalline grain was increased with increasing the Cs-oleate as excess oleylamine. The quantum yield for 14S4DN reached to 99.3 % due to the decrease of defects and the surface passivation of Cs4PbBr6. There are more oleylammonium bromide on the surface of CsPbBr3 NCs as synthesized with 1,9-dibromnonane. The ligand shell and the surface passivation of Cs4PbBr6 restrained the decomposition of surface, consequently improved the stability of moisture and light for CsPbBr3 NCs. When the CsPbBr3@Cs4PbBr6 NCs were immersed in water under UV light (365 nm) for 2 h, the PL intensity could retain 90.4 %, while the 11S1 (traditional CsPbBr3 NCs) was only 10.9 %. It indicated the stability of moisture and light for CsPbBr3 NCs were greatly improved, because Cs4PbBr6 NCs effectively passivated the surface of CsPbBr3 NCs and restrained the generation of traps states.
 Select Dynamic recrystallization behavior and interfacial bonding mechanism of 14Cr ferrite steel during hot deformation bonding Liying Zhou, Wenxiong Chen, Shaobo Feng, Mingyue Sun, Bin Xu, Dianzhong Li J. Mater. Sci. Technol., 2020, 43 (0): 92-103.  DOI: 10.1016/j.jmst.2020.01.010 In this study, hot compression bonding was first applied to join 14Cr ferrite steel at temperatures of 950-1200 °C and strains of 0.11-0.51 under strain rates of 0.01-30 s-1. Subsequently, tensile tests were performed on the joints to evaluate the reliability of the joints formed. Detailed microstructural analyses suggest that two different competing dynamic recrystallization (DRX) mechanisms occur during the bonding process depending on the strain rate, and the joints obtained at different strain rate exhibits distinct healing effect. At a low strain rate (0.01 s-1), continuous DRX occurs, as expected in high-stacking-fault-energy materials, and is characterized by the progressive conversion of the sub-boundaries into larger-angle boundaries, which involves very limited grain boundaries migration. In addition, strain-induced precipitation (SIP) is sufficient under this condition, further impeding the healing of bonding interface. Hence, the joints obtained at low strain rate fractured at the bonding interface easily. Whereas discontinuous DRX is activated at high strain rates (10 and 30 s-1). Under this condition, the formation of sub-boundaries is severely suppressed, resulting in the piling-up of dislocations and hence the storage of a greater amount of stored energy for nucleation and subsequent nuclei growth via the long-distance grain boundaries migration. Meanwhile, the SIP process is sluggish, making the conditions much more favorable for grain boundaries migration which plays a key role in the healing of the original bonding interface. Thus, the joints can be successfully bonded when a high strain rate is applied, with the joints exhibiting tensile properties similar to that of the base material.
 Select Unveiling annealing texture formation and static recrystallization kinetics of hot-rolled Mg-Al-Zn-Mn-Ca alloy Qinghang Wang, Bin Jiang, Aitao Tang, Jie Fu, Zhongtao Jiang, Haoran Sheng, Dingfei Zhang, Guangsheng Huang, Fusheng Pan J. Mater. Sci. Technol., 2020, 43 (0): 104-118.  DOI: 10.1016/j.jmst.2020.01.018 The development of Mg-Al-Zn-Mn-Ca series alloys provides a potential prospect to achieve high strength and formability at room temperature (RT). The formation of elliptical annular texture is treated as a crucial factor for the enhanced RT formability. However, the origin of such an elliptical annular texture formation has been rarely reported. Herein, we unveiled the formation and evolution of elliptical annular texture in the hot-rolled Mg-1.6Al-0.8Zn-0.4Mn-0.5Ca (AZMX1100, wt.%) alloy after annealing at different temperatures for 1 h, and its static recrystallization (SRX) kinetics in given annealing temperature for different time. The results revealed that the formation of elliptical annular texture in the hot-rolled AZMX1100 alloy after annealing was derived from nucleation-oriented SRX mechanism, which took place in 200-300 °C, induced by cracked chain-shaped Al2Ca phases, contraction twins, intersections of double twins, intersections of double twins and grain boundaries and non-basal slips. On further annealing from 300-450 °C, the grains with 45°-70° transverse direction (TD) preferentially grew, which made elliptical annular texture extended along the TD. Based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model, Avrami exponent n value was estimated to be 0.68-1.02, attributed to non-random SRX nucleation, giving rise to the lower activation energy QR of nucleation of ～74.24 kJ/mol. Since the co-segregation of Al, Zn and Ca atoms in grain boundaries created a strong interaction of solutes and grain boundaries, the hot-rolled AZMX1100 alloy exhibited the higher activation energy Qg (～115.48 kJ/mol) of grain growth.
 Select Enhancing strength and plasticity by pre-introduced indent-notches in Zr36Cu64 metallic glass: A molecular dynamics simulation study Shidong Feng, n Li, K.C. Chan, Lei Zhao, Limin Wang, Riping Liu J. Mater. Sci. Technol., 2020, 43 (0): 119-125.  DOI: 10.1016/j.jmst.2019.10.034 The deformation behavior in Zr36Cu64 metallic glasses with pre-introduced indent-notches has been studied by molecular dynamics simulation at the atomic scale. The indent-notches can trigger the formation of densely-packed clusters composed of solid-like atoms in the indent-notch affected zone. These densely-packed clusters are highly resistant to the nucleation of shear bands. Hence, there is more tendency for the shear bands to nucleate outside the indent-notch affected zone, which enlarges the deformation region and enhances both the strengthening effect and the plastic deformation ability. For indent-notched MGs, when determining the initial yielding level, there is a competition process occurring between the densely-packed clusters leading to the shear band formation outside the indent-notch affected zone and the stress-concentration localizing deformation around the notch roots. When the indent-notch depth is small, the stress-concentration around the notch root plays a dominant role, leading to the shear bands initiating from the notch root, reminiscence of the cut-notches. As the indent-notch depth increases, there are many densely-packed clusters with high resistance to deformation in the indent-notch affected zone, leading to the shear band formation from the interface between the indent-notch affected zone and the matrix. Current research findings provide a feasible means for improving the strength and the plasticity of metallic glasses at room temperature.
 Select Microstructure evolution of nanostructured ferritic alloy with and without Cr3C2 coated SiC at high temperatures Kaustubh Bawane, Kathy Lu J. Mater. Sci. Technol., 2020, 43 (0): 126-134.  DOI: 10.1016/j.jmst.2019.10.028 This work focuses on fundamental understanding of microstructure evolution of nanostructured ferritic alloy (NFA) and 25 vol.% Cr3C2 coated SiC(Cr3C2@SiC)-NFA composite during spark plasma sintering at 950 °C and the following thermal treatment at 1000 °C. A unique bi-phase microstructure with distinct Cr-rich and Si-rich phases has been observed for the 25 vol.% Cr3C2@SiC-NFA composite, while for the NFA sample, the traditional large grain microstructure remains. Grain sizes are significantly smaller for the 25 vol.% Cr3C2@SiC-NFA composite compared to those for the pure NFA, which can be attributed to the presence of grain boundary phases in the composite sample. During the thermal treatment, microstructure features can be directly correlated with the dissolution kinetics and phase diagrams calculated using Thermo-Calc/DICTRA/PRISMA®.
 Select New para-magnetic (CoFeNi)50(CrMo)50-x(CB)x (x = 20, 25, 30) non-equiatomic high entropy metallic glasses with wide supercooled liquid region and excellent mechanical properties Kim Jeong Tae, Hong Sung Hwan, Park Jin Man, Jürgen Eckert, Kim Ki Buem J. Mater. Sci. Technol., 2020, 43 (0): 135-143.  DOI: 10.1016/j.jmst.2020.01.004 In this study, high entropy metallic glasses (HEMGs) were developed through a combination of concepts for designing metallic glasses (main element + transition metal + metalloid element) and high-entropy alloys (more than five elements, each element having an atomic concentration between 5 at.% and 35 at.%). The developed metallic glass alloys are composed of Co-Fe-Ni main elements, transition metals (Cr, Mo) and metalloid elements (C, B). Moreover, the present work reports the thermal, mechanical and magnetic properties of (CoFeNi)50(CrMo)50-x(CB)x alloys with x = 20, 25, 30. The developed as-spun HEMGs exhibit typical paramagnetic properties even for a high amount of ferromagnetic elements (Co, Fe, and Ni) and have high elastic modulus (103-160 GPa) and hardness (14-27 GPa), thus possessing mechanical properties similar to well-known Co-based metallic glasses (Co-Cr-Mo-C-B system). In addition, some of the bulk samples prepared with a diameter of 2 mm form bulk metallic glasses with a high compressive strength around 3.5 GPa. The mechanisms determining the stability of the supercooled liquid, as well as the paramagnetic and mechanical properties for the developed non-equiatomic HEMGs, are discussed.
 Select 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 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.
 Select 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 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.
 Select SERS-encoded nanocomposites for dual pathogen bioassay Yaqi Shan, Mingliang Wang, Zengliang Shi, Milan Lei, Xiaoxuan Wang, Fu-Gen Wu, Huan-Huan Ran, Gowri Manohari Arumugam, Qiannan Cui, Chunxiang Xu J. Mater. Sci. Technol., 2020, 43 (0): 161-167.  DOI: 10.1016/j.jmst.2019.10.032 Surface-enhanced Raman spectroscopy (SERS) has been successfully applied to detect various biomolecules, but it is still in challenge to assay living cells or bacteria sensitively, selectively and quantitatively in complex environments. In this paper, 4-ATP and DTNB are assembled on Ag nanoparticle (NP) -decorated poly (styrene-co-acrylic acid) (PSA) nanospheres and then sealed by silica shells to form sensitive SERS labels based on the localized surface plasmon resonance of Ag NPs and large light scattering cross-sections of PSA nanospheres. They are further developed as encoding tags for dual detection of S. aureus and E. coli after assembling corresponding aptamers, which demonstrate ultralow detection limits of 8 cell L-1 for S. aureus and 2 cell L-1 for E. coli. Such a bioassay indicates a point-of-care strategy of ultrasensitively biomedical detections by encoding specific SERS tags.
 Select 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 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.
Invited Review
 Select 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 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.
Research Article
 Select Formation of spherical alloy microparticles in a porous salt medium Nersisyan Hayk H., Kwon Suk Cheol, Ri Vladislav E., Kim Wan Bae, Choi Woo Seok, Lee Jong Hyeon J. Mater. Sci. Technol., 2020, 43 (0): 189-196.  DOI: 10.1016/j.jmst.2019.10.029 This study describes the development of a one-pot strategy to produce spherical alloy microparticles for advanced near-net-shape manufacturing processes, including additive manufacturing and powder injection molding. The AlSi12 eutectic alloy (ca. 12 wt% Si) system was chosen as the model with which the main experiments were carried out. The proposed process synergistically integrates a few common, low-cost processing techniques including the mixing of Al micrometer size particles with silicon and sodium chloride, heat-treating the mixture at temperatures of 650-810 °C, and the dissolution of salt in water to produce spherical AlSi12 alloy particles without the need to rely on costly melting and atomizing techniques. This new process can use laow-cost source Al and Si powders as the raw materials to produce 10-200 μm-sized spherical particles of AlSi12. The Ansys-CFX computational fluid dynamics software was used to analyze the flow behavior of AlSi12 liquid droplets and particle size refinement in the narrow voids of the sample.
 Select Neuroprotective effect of chitosan nanoparticle gene delivery system grafted with acteoside (ACT) in Parkinson’s disease models Yongyong Xue, Na Wang, Zhi Zeng, Jinpeng Huang, Zhiming Xiang, Yan-Qing Guan J. Mater. Sci. Technol., 2020, 43 (0): 197-207.  DOI: 10.1016/j.jmst.2019.10.013 Developing new drugs to treat Parkinson's disease efficiently is challenging. Here we report that chitosan nanoparticles (APPDNs) could serve as novel candidates for the design of anti-PD drugs. In this study, we investigated the effects of chitosan poly ethyleneglycol-poly lactic acid (PEG-PLA) nanoparticles conjugated with nerve growth factor (NGF), acteoside (ACT) and plasmid DNA (pDNA) for PD therapy using in vitro and in vivo models. Using PD cell models, we demonstrated that APPDN had good neuroprotective effects. More significantly, experiments using mouse PD models demonstrated that APPDNs could ameliorate the behavioral disorders of sick mice. Immunohistochemical and western blot (WB) analyses demonstrated that APPDNs could significantly reverse dopaminergic (DA) neuron loss in the substantia nigra and striatum of sick mice. This study opens up a novel avenue to develop anti-PD drugs.
 Select Microstructure and mechanical properties of sand-cast Mg-6Gd-3Y-0.5Zr alloy subject to thermal cycling treatment Beiping Zhou, Wencai Liu, Guohua Wu, Liang Zhang, Xiaolong Zhang, HaoJi Wen, jiang Ding J. Mater. Sci. Technol., 2020, 43 (0): 208-219.  DOI: 10.1016/j.jmst.2020.01.013 This work was undertaken to investigate the microstructural evolution, mechanical properties and fracture behavior of sand-cast Mg-6Gd-3Y-0.5 Zr (GW63) alloy subject to thermal cycling treatment. In order to simulate the thermal cycling under extreme service conditions (space or moon environments), the sand-cast and T6 treated GW63 alloys were subjected to thermal cycling treatment which consists of deep cryogenic-elevated temperature cycling treatment (DCET) and deep cryogenic cycling treatment (DCT). Results indicate that there are significant gains in yield strength (YS) and ultimate tensile strength (UTS) of the sand-cast GW63 alloy after DCET, whereas the T6 state alloy undergoes a different variation in mechanical properties. However, no appreciable influence is revealed on the mechanical properties of the tested GW63 alloys after DCT. Meanwhile, the DCT and DCET have no obvious effects on the fracture morphology. The DCT enhances the precipitation kinetics via providing favorable nucleation sites for the precipitation of second phases. The elevated temperature process of DCET plays a crucial role in improving the aging-hardening responses and releasing the stress concentration brought by DCT to a great extent, leading to overcome the obstacle of essential phase transformation. The changes in mechanical properties are primarily attributed to the phase transformation of the studied alloys during DCET.
 Select The dynamic responses of lamellar and equiaxed near β-Ti alloys subjected to multi-pass cross rolling Wei Chen, Hande Wang, Y.C. Lin, Xiaoyong Zhang, Chao Chen, Yaping Lv, Kechao Zhou J. Mater. Sci. Technol., 2020, 43 (0): 220-229.  DOI: 10.1016/j.jmst.2019.10.017 This work gives a comparison on the microstructural characteristics, textural discrepancies, and twinning behaviors of lamellar and equiaxed near β-Ti alloys during multi-pass cross rolling with a rolling reduction of 20 %, 50 % and 80 %. The results showed that the restoration mechanism of the alloy in β phase is strongly dependent on the α morphologies, and in comparison, strain path has weaker influences on the grain refinement of the β matrix. Therefore, the texture intensities of both α and β phases were weakened owing to the dynamic recrystallization (DRX) of the two phases in the equiaxed microstructure. While, with regard to the lamellar microstructure, dynamic recovery (DRV) of the β phase predominated, forming elongated β subgrains. Besides, the α and β matrix in lamellar microstructures obeyed the Burgers orientation relationship, which was gradually broken down until the final reduction. Lastly, the {1$\bar{1}$01} twinning exhibits a strong size effect. With the continuous DRX of α phases, the α-twinning is suppressed owing to progressive grain refinement. The activation of β-twinning, namely {332}〈113〉 and {112}〈111〉, in near β-Ti alloys is heavily dependent on the deficient β-stabilizing elements and the local stress concentration. These findings provide an effective way to obtain ultra-fine grain microstructures of this alloy.
 Select Towards understanding twinning behavior near fracture surface in magnesium Hao Li, Qinghui Zeng, Pengfei Yang, Qi Sun, Jianmin Wang, Jian Tu, Minhao Zhu J. Mater. Sci. Technol., 2020, 43 (0): 230-237.  DOI: 10.1016/j.jmst.2020.01.007 Deformation twin is one of the most important strain accommodation mechanisms and ultimately influences the mechanical properties for magnesium and its alloys. Especially, {10$\bar{1}$1} twin is usually thought to be closely related to the fracture or fatigue process of magnesium alloys. In the present work, the characteristics of microstructure near fracture region of deformed magnesium alloy have been investigated by a combination of electron back-scatter diffraction (EBSD) and transmission electron microscope (TEM). It has found that a large of deformation twins occur near fraction region, including {10$\bar{1}$2} and {10$\bar{1}$1} primary twins, {10$\bar{1}$1}-{10$\bar{1}$2} double twin and {10$\bar{1}$1}-{10$\bar{1}$2}-{10$\bar{1}$1}-{10$\bar{1}$2} quadruple twin. The actual boundaries of {10$\bar{1}$1} twins at atomic scale consist of {10$\bar{1}$1} coherent twinning boundaries (TBs) and parallel basal-pyramidal (BPy/PyB) planes. The tip of {10$\bar{1}$1} twin can even end up with BPy/PyB interfaces only. The experimental observations also reveal that when two {10$\bar{1}$1} twin variants sharing a common [11$\bar{2}$0] zone axis approach each other, the growth of one twin is usually hindered by the boundaries of the other twin. In addition, an apparent “crossing” phenomenon is also discovered when interaction of two {10$\bar{1}$1} twins takes place. According to these experimental observations, the possible underlying mechanisms behind such phenomena are proposed and discussed. These finding are expected to provide an insight into understanding the twinning behavior and the relationship between twin and fracture in magnesium and other materials with hexagonal structure.
ISSN: 1005-0302
CN: 21-1315/TG
Editorial Office: Journal of Materials Science & Technology , 72 Wenhua Rd.,
Shenyang 110016, China
Tel: +86-24-83978208
E-mail:JMST@imr.ac.cn