Diverse foraging strategies of breeding Swinhoe's Storm-petrel in the productive marginal sea of the Northwest Pacific

Understanding the foraging behavior is essential for investigating seabird ecology and conservation,as well as monitoring the well-being of the marine environment.Breeding seabirds adopt diverse foraging strategies to maximize energy gains and cope with the intensified challenges of parenting and self-maintenance.Such tradeoff may stem from the heterogeneity of food resources and the constraints of central place foraging.Nevertheless,abundant marine productivity could alleviate the energy limitation for seabirds,resulting in a consistent foraging approach.Here,we investigated the foraging strategy during the breeding season of a cryptic small-sized seabird,Swinhoe’s Storm-petrel(Hydrobates monorhis),in the Yellow Sea,a productive marginal sea of the Northwest Pacific.Using GPS tracking,we evaluated habitat preference,quantified the foraging strategy,and tested if environmental conditions and individual traits influence foraging trips.We found that Swinhoe’s Storm-petrels preferred nearshore areas with shallow water and engaged in primarily short foraging trips.Distinctive southeastward and southwestward strategies emerged when combining trip metrics,including foraging direction,duration,and maximum distance.The bathymetry,proximity to the coastline,and sea surface temperature differed in two foraging strategies.Foraging strategies exhibited flexibility between individuals,potentially explained by wing morphology,in which longer-winged birds are more likely to embark on longer-distance foraging trips.These findings highlight the impact of environmental factors and individual traits on seabirds’foraging decisions in productive marginal sea ecosystems.Our study also provides valuable insights into the foraging ecology of this Asian endemic storm-petrel.

Metal-organic interface engineering for boosting the electroactivity of Pt nanodendrites for hydrogen production

Recently, the surface chemical functionalization and morphology control of precious metal nanostructures have been recognized as two efficient strategies for improving their electroactivity and/or selectivity. In this work, 1, 10-phenanthroline monohydrate(PM) functionalized Pt nanodendrites(Pt-NDs) on carbon cloth(CC)(denoted as PM@Pt-NDs/CC) and polyethylenimine(PEI) functionalized Pt-NDs on CC(denoted as PEI@Pt-NDs/CC) are successfully achieved by immersing Pt-NDs/CC into PM and PEI aqueous solutions, respectively. PEI functionalization of Pt-NDs/CC improves its electroactivity for hydrogen evolution reaction(HER) due to local proton enrichment whereas PM functionalization of Pt-NDs/CC improves its electroactivity for formic acid oxidation reaction(FAOR) by facilitating dehydrogenation pathway. With such high activity, a two-electrode electrolyzer is assembled using PM@Pt-NDs/CC as the anodic electrocatalyst and PEI@Pt-NDs/CC as the cathodic electrocatalyst for electrochemical reforming of formic acid, which only requires 0.45 V voltage to achieve the current density of 10 mA cm^(-1) for highpurity hydrogen production, much lower than conventional water electrolysis(1.59 V). The work presents an example of interfacial engineering enhancing electrocatalytic activity and indicates that electrochemical reforming of formic acid is an energy-saving electrochemical method for high-purity hydrogen production.

Impact of W alloying on microstructure, mechanical property and corrosion resistance of face-centered cubic high entropy alloys: A review

Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.

Cooling System Design Optimization of an Enclosed PM Traction Motor for Subway Propulsion Systems

This paper presents the design optimization of a self-circulated ventilation system for an enclosed permanent magnet(PM)traction motor utilized in the propulsion systems for subway trains.In order to analyze accurately the machine's inherent cooling capacity when the train is running,the ambient airflow and the related heat transfer coefficient(HTC)are numerically investigated considering synchronously the bogie installation structure.The machine is preliminary cooled with air ducts set on the motor shell,and the fluidic-thermal field distributions with only the shell air duct cooling are numerically calculated.During simulations,the HTC obtained in the former steps is applied to the external surface of the machine to model the inherent cooling characteristic caused by the train movement.To reduce the temperature rise and thus guarantee the motor's working reliability,an internal self-circulated air cooling system is proposed according to the machine temperature distribution.The air enclosed in the end-caps is driven by the blades mounted on both sides of the rotor core and forms two air circuits to bring the excessive power losses generated in the heating components to cool regions.The fluid flow and temperature rise distributions of the cooling system's structural parameters are further improved by the Taguchi method in order to confirm the efficacy of the internal air cooling system.

The Spin Measurement of MAXI J0637-430:a Black Hole Candidate with High Disk Density

The Galactic black hole candidate MAXI J0637-430 was first discovered by MAXI/GSC on 2019 November 2.We study the spectral properties of MAXI J0637-430 by using the archived NuSTAR data and Swift/XRT data.After fitting the eight spectra by using a disk component and a powerlaw component model with absorption,we select the spectra with relatively strong reflection components for detailed X-ray reflection spectroscopy.Using the most state-of-art reflection model,relxillCp,the spectral fitting measures a black hole spin a_(*)>0.72 and the inclination angle of the accretion disk i=46.1_(-5.3)^(+4.0)degrees,at a 90%confidence level.In addition,the fitting results show an extreme supersolar iron abundance.Combined with the fitting results of reflection model reflionx_hd,we consider that this unphysical iron abundance may be caused by a very high-density accretion disk(n_(e)>2.34×10^(21)cm^(-3))or a strong Fe K_(α) emission line.The soft excess is found in the soft state spectral fitting results,which may be an extra free-free heating effect caused by high density of the accretion disk.Finally,we discuss the robustness of black hole spin obtained by X-ray reflection spectroscopy.The result of relatively high spin is self-consistent with broadened Fe K_(α) line.Iron abundance and disk density have no effect on the spin results.

RNF2在结直肠癌中的表达及其对结直肠癌细胞生物学行为的影响

目的探讨环指蛋白2 (RNF2)在结直肠癌中的表达及其对结直肠癌细胞生物学行为的影响。方法采用免疫组织化学法检测RNF2在结直肠癌组织和癌旁正常组织中的表达,并利用过表达的慢病毒转染HCT116细胞构建过表达RNF2的HCT116细胞系,通过CCK-8法、划痕实验、Transwell实验检测过表达RNF2对结直肠癌细胞增殖、迁移、侵袭等生物学行为的影响。结果结直肠癌组织中RNF2阳性表达率高于癌旁正常组织(P <0.05);不同年龄、组织学类型、分化程度、Dukes分期、淋巴结转移的结直肠癌患者的RNF2表达阳性率比较,差异有统计学意义(P <0.05);HCT116组、HCT116-control组、HCT116-RNF2组HCT116细胞增殖、迁移能力及侵袭能力比较,差异有统计学意义(P <0.05);HCT116-RNF2组细胞增殖速度、迁移能力及侵袭能力均高于HCT116-control组和HCT116组(P <0.05)。结论 RNF2在结直肠癌中呈高表达,且过表达RNF2可促进结直肠癌细胞迁移、增殖、侵袭能力,可为结直肠癌治疗提供新的治疗靶点。

胃癌根治术后切缘阳性患者的临床病理特征和预后分析

目的:探讨胃癌根治术后切缘阳性患者的临床病理特征及其对预后影响。方法:回顾性分析河北医科大学第四医院2011年1月至2016年1月收治的胃癌根治术后切缘阳性患者的临床病理资料。按1∶2随机数法选取同期收治的切缘阴性患者,比较阳性和阴性切缘患者的一般临床病理学特征及预后情况。结果:共纳入73例切缘阳性患者,与同期纳入的146例切缘阴性病例比较,阳性组的肿瘤直径更大、更多位于贲门或全胃,组织学类型更差、Lauren分型趋于弥漫型、Borrmann分型多为Ⅲ~Ⅳ型、肿瘤浸润深度以T4a~4b为主、pTNM分期更晚,脉管浸润率及淋巴结转移率也更高,同时术者经验、手术方式的差异也与阳性切缘发生有关(均P<0.05)。全组共有205例患者获得完整随访,两组患者5年总生存(overall survival,OS)率及无进展生存(progression-free survival,PFS)率均有显著性差异(23.19%vs.58.82%,15.94%vs.47.06%,均P<0.001)。Cox多因素分析显示,切缘状态(P=0.012)、pTNM分期(P=0.023)及术后综合治疗(化疗/化疗联合放疗)(P<0.001)是影响胃癌预后的独立因素。结论:胃癌根治术后切缘状态与多种临床病理特征相关,切缘阳性患者预后较差。

Strengthening mechanisms of reduced activation ferritic/martensitic steels:A review

This review summarizes the strengthening mechanisms of reduced activation ferritic/martensitic(RAFM)steels.High-angle grain boundaries,subgrain boundaries,nano-sized M_(23)C_(6),and MX carbide precipitates effectively hinder dislocation motion and increase high-temperature strength.M23C6 carbides are easily coarsened under high temperatures,thereby weakening their ability to block dislocations.Creep properties are improved through the reduction of M23C6 carbides.Thus,the loss of strength must be compensated by other strengthening mechanisms.This review also outlines the recent progress in the development of RAFM steels.Oxide dispersion-strengthened steels prevent M23C6 precipitation by reducing C content to increase creep life and introduce a high density of nano-sized oxide precipitates to offset the reduced strength.Severe plastic deformation methods can substantially refine subgrains and MX carbides in the steel.The thermal deformation strengthening of RAFM steels mainly relies on thermo-mechanical treatment to increase the MX carbide and subgrain boundaries.This procedure increases the creep life of TMT(thermo-mechanical treatment)9Cr-1W-0.06Ta steel by~20 times compared with those of F82H and Eurofer 97 steels under 550℃/260 MPa.

Preparation and evaluation of poly(L-histidine) based pH-sensitive micelles for intracellular delivery of doxorubicin against MCF-7/ADR cells

In this study, a p H-sensitive micelle self-assembled from poly(L-histidine) based triblock copolymers of poly(ethylene glycol)–poly(D,L-lactide)–poly(L-histidine)(mPEG-PLA-PHis) was prepared and used as the intracellular doxorubicin(Dox) delivery for cancer chemotherapy. Dox was loaded into the micelles by thin-film hydration method and a Box–Behnken design for three factors at three levels was used to optimize the preparations. The optimized mPEG-PLA-Phis/Dox micelles exhibited good encapsulation efficiency of 91.12%,a mean diameter of 45 nm and narrow size distribution with polydispersity index of 0.256.In vitro drug release studies demonstrated that Dox was released from the micelles in a p Hdependent manner. Furthermore, the cellular evaluation of Dox loaded micelles displayed that the micelles possessed high antitumor activity in vitro with an IC50 of 35.30 μg/ml against MCF-7/ADR cells. The confocal microscopy and flow cytometry experiments indicated that m PEG-PLA-Phis micelles mediated efficient cytoplasmic delivery of Dox with the aid of poly(Lhistidine) mediated endosomal escape. In addition, blank m PEG-PLA-Phis micelles were shown to be nontoxic to MCF-7/ADR cells even at a high concentration of 200 μg/ml. The pHsensitive mPEG-PLA-PHis micelles have been demonstrated to be a promising nanosystem for the intracellular delivery of Dox for MDR reversal.

Effects of Yinzhihuang oral liquid and albumin on bilirubin, inflammatory factors, immune indexes and related factors in neonatal pathologic jaundice

Objective: To explore the effects of Yinzhihuang oral liquid and albumin on bilirubin, inflammatory factors, immune indexes and related factors in neonatal pathologic jaundice. Methods: A total of 134 neonates with pathologic jaundice admitted to our hospital from May 2017 to April 2018 were randomly selected as the control group (n=67) and the observation group (n=67), the control group was treated with albumin, the observation group was treated with Yinzhihuang Oral Liquid on the basis of the control group. The bilirubin, inflammatory factors, immune indicators, alpha-fetoprotein (AFP) and transferrin (TRF) were compared and analyzed before and after treatment. Results: After treatment, the levels of TBIL, DBIL and IBIL in both groups were significantly lower than those before treatment (P<0.05), and the levels of TBIL, DBIL and IBIL [(118.60±10.85) μmol/L, (6.95±1.52) μmol/L, (115.30±14.20)μmol/L] in observation group were significantly lower than those in control group;the levels of CRP and IL-6 in both groups were significantly lower than those before treatment (P<0.05), and the levels of CRP and IL-6 [(8.26±2.07) mg/L, (12.69±2.15) pg/mL] in observation group were significantly lower than those in control group (P<0.05);the levels of CD4+, CD4+/CD8+ in both groups were significantly higher than those before treatment (P<0.05), while the levels of CD8+ was significantly lower than that before treatment, the levels of CD4+, CD4+/CD8+ [(47.08±5.70)%, (2.08±0.41)] in observation group were significantly higher than those in control group (P<0.05), and the level of CD8+ [(22.90±2.05)%] was significantly lower than that in control group (P<0.05);the levels of AFP in significantly higher than before treatment (P<0.05), and the levels of AFP [(12.69±3.04)mg/L] in observation group were significantly lower than those in control group (P<0.05), the levels of TRF [(2.02±0.35) g/L] were significantly higher than those in control group (P<0.05). Conclusions: The combination of Yinzhihuang oral liquid and albumin can effectively reduce the bilirubin level in neonatal jaundice, inhibit its inflammatory reaction, enhance the cellular immune function and improve the expression of AFP and TRF, which is of clinical significance.

Hygrothermal effect on high-velocity impact resistance of woven composites

The woven glass fiber reinforced composites(GFRP)subjected to high-speed impact is investigated to identify the hygrothermal aging effect on the impact resistance.Both the hygrothermal aged and unaged glass/epoxy laminates are subjected to different impact velocities,which is confirmed as a sensitive factor for the failure modes and mechanisms.The results show the hygrothermal aging effect decreases the ballistic limit by 14.9%,but the influence on ballistic performance is limited within the impact velocity closed to the ballistic limit.The failure modes and energy dissipation mechanisms are confirmed to be slightly influenced by the hygrothermal aging effect.The hygrothermal aging effect induced localization of structural deformation and degradation of mechanical properties are the main reasons for the composite undergoing the same failure modes at smaller impact velocities.Based on the energy absorption mechanisms,analytical expressions predict the ballistic limit and energy absorption to reasonable accuracy,the underestimated total energy absorption results in a relatively poor agreement between the measured and predicted energy absorption efficiency.

Reference and Application of Peking Opera Aria in National Vocal Music Singing

Peking Opera is one of ancient opera arts in China, known as the ＂national essence＂ , which has a very high artistic achievement. Because of its unique and systematic aria, phonology, performance and modeling, Peking Opera is favored by people, which is an art that vocal music artists mutually research and learn. The Peking Opera aria has already formed a set of professional theories, which has practical significance to guide the national vocal music. It not only can inherit the Peking Opera but also can carry forward the national vocal music. This paper illustrates the reference and application of Peking Opera aria in national vocal music singing according to examples, which provides the reference advice for the development of national vocal music.

液态金属镶嵌半导体颗粒光电极中金属/半导体3D界面电子结构调控促进光电化学分解水

光电极通常由半导体吸光层和导电集流体两部分组成,两者间的界面电子结构直接影响导电集流体从半导体光吸收层中收集光生电荷的效率,尤其对于具有3D界面结构的液态金属镶嵌半导体颗粒的光电极.为此,本工作通过改变金属组分改变液态金属的功函数,从而调节导电集流体与半导体吸光材料间3D界面的电子能带排列和接触类型,促进光生电荷的跨界面转移与收集,提升光电极的光电化学分解水活性.系统研究半导体与液态金属的功函数匹配关系发现,将ZnO颗粒嵌入铟锡(IT)低温液态金属中,会形成欧姆接触;而将其嵌入铋铟锡(BIT)低温液态金属中,则会形成肖特基接触.由于欧姆接触不存在肖特基接触的界面能垒而有利于光生电荷的跨界面转移与收集,因此,与铟锡低温液态金属镶嵌ZnO颗粒的光电极(IT/ZnO)相比铋铟锡低温液态金属镶嵌ZnO颗粒的光电极(BIT/ZnO)具有更为优异的电荷收集和分离能力,其光电化学分解水光电流密度可达0.62 mA cm^(-2),相比BIT/ZnO光电极的光电流密度(0.52 mA cm^(-2))提升了约19%,且在已报道的代表性ZnO光电极中处于前列.而与之相比,WO3、TiO_(2)或Cu2O因分别与IT和BIT形成相同的欧姆或肖特基型接触,两种低温液态金属镶嵌的WO3、TiO_(2)或Cu2O光电极具有几乎相同的光电催化活性.本工作展示了通过选择具有不同功函数的液态金属来改变金属/半导体接触类型以增强低温液态金属镶嵌半导体光电极性能的潜力,为规模化构建高效光电极提供了新的策略.

Green batch prepared a novel C/P co-doping urchin-like TiO_(2)for enhanced photocatalytic degradation and mineralization of trimethoprim

In advancing the practical application of photocatalytic degradation for pollutant removal,batch preparation of environmentally friendly photocatalysts plays a crucial role.Herein,we prepared C/P co-doped urchin-like TiO_(2)(C/PeTiO_(2))through a straightforward room temperature impregnation and atmospheric annealing process.Phytic acid served as the dopant precursor for introducing C and P onto the TiO_(2)surface.This doping process was verified through energy dispersive X-ray spectroscopy(EDX),electron spin resonance(ESR),and X-ray photoelectron spectroscopy(XPS)analysis.The C/PeTiO_(2)photocatalyst exhibited exceptional efficiency in degrading the target compound trimethoprim(TMP),achieving a degradation of 98%TMP within 60 min and a mineralization of 40%TMP within 120 min,which were respectively 2.4 and 1.6 times higher than that of pristine TiO_(2).The intermediate products of TMP were detected,and a plausible degradation pathway was proposed.Photoelectric characterization results also confirmed that C/P co-doping could effectively enhance the carrier separation efficiency of C/PeTiO_(2).The catalysts prepared using the scaled-up impregnation system and reusing the phytic acid solution consistently demonstrated stable catalytic performance,which confirmed the viability of the method for green and batch preparation of C/P co-doped TiO_(2).Notably,the obtained catalyst consistently exhibited high degradation efficacy in various real water bodies,highlighting its substantial potential for practical application.The green and batch preparation method of C/PeTiO_(2)introduces a novel approach to the practical application of photocatalysis technology in treatment of water contaminants.

N-doped carbon nanocages： Bifunctional electrocatalysts for the oxygen reduction and evolution reactions

Highly effident metal-free, carbon-based, bi-functional electrocatalysts for the oxygen evolution reaction （OER） and oxygen reduction reaction （ORR） have attracted increased attention for use in electrochemical energy conversion systems, owing to their low cost and high activity. In this work, N-doped carbon nanocages （N-CCs） with a porous self-supported architecture and high specific surface area are synthesized by a facile interfacial assembly synthetic route. The materials are comprehensively characterized by scanning electron microscop36 transmission electron microscopy, nitrogen adsorption-desorption experiments, X-ray diffraction, and X-ray photoelectron spectroscopy. Cyclic voltammetry , chronoamperometry, and linear sweep voltammetry demonstrate that the as-prepared N-CC could serve as an effective metal-free electrocatalyst with excellent catalytic activity, long-term operation durability, and excellent methanol tolerance for the ORR in alkaline media. In the presence of 3 mM methanol, the half wave potential of the N-CCs for the ORR is 190 mV; this is more positive than that of the commercial Pt/C electrocatalyst. Meanwhile, the N-CCs also show an OER activity comparable to that of the commercial Ru/C electrocatalyst, revealing their bifunctional property.

Stoichiometry of base cations and silicon during weathering of a deep soil profile derived from granite

Evaluation of the stoichiometry of base cations(BCs,including K^(+),Na^(+),Ca^(2+),and Mg^(2+))and silicon(Si)(BCs:Si)during soil mineral weathering is essential to accurately quantify soil acidification rates.The aim of this study was to explore the differences and influencing factors of BCs:Si values of different soil genetic horizons in a deep soil profile derived from granite with different extents of mineral weathering.Soil type was typic acidi-udic Argosol.Soil samples were collected from Guangzhou,China,which is located in a subtropical region.To ensure that the BCs and Si originated from the mineral weathering process,soil exchangeable BCs were washed with an elution treatment.The BCs:Si values during weathering were obtained through a simulated acid rain leaching experiment using the batch method.Results showed that soil physical,chemical,and mineralogical properties varied from the surface horizon to saprolite in the soil profile.The BCs:Si values of soil genetic horizons during weathering were 0.3–3.7.The BCs:Si value was 1.7 in the surface horizon(A),1.1–3.7 in the argillic horizon(Bt),and 0.3–0.4 in the cambic(Bw)and transition(BC)horizons,as well as in horizon C(saprolite).The general pattern of BCs:Si values in the different horizons was as follows:Bt>A>Bw,BC,and C.Although BCs:Si values were influenced by weathering intensity,they did not correlate with the chemical index of alteration(CIA).The release amounts of Si and BCs are the joined impact of soil mineral composition and physical and chemical properties.A comprehensive analysis showed that the BCs:Si values of the soil derived from granite in this study were a combined result of the following factors:soil clay,feldspar,kaolinite,organic matter,pH,and CIA.The main controlling factors of BCs:Si in soils of different parent material types require extensive research.The wide variance of BCs:Si values in the deep soil profile indicated that H+consumed by soil mineral weathering was very dissimilar in the soils with different weathering intensities derived from the same parent material.Therefore,the estimation of the soil acidification rate based on H+biogeochemistry should consider the specific BCs:Si value.

A first-principle assisted framework for designing high elastocaloric Ni-Mn-based magnetic shape memory alloy

A large adiabatic temperature change(△T_(ad))is a prerequisite for the application of elastocaloric refriger-ation.Theoretically,a large volume change ratio(△V/V_(0))during martensitic transformation is favorable to enhance△T_(ad).However,the design or prediction of△V/V_(0)in experiments is a complex task because the structure of martensite changes simultaneously when the lattice parameter of austenite is tuned by mod-ifying chemical composition.So far,the solid strategy to tailor△V/V_(0)is still urgently desirable.In this work,a first-principles-based method was proposed to estimate△V/V_(0)for Ni-Mn-based alloys.With this method,the substitution of Ga for In is found to be an effective method to increase the value of△V/V_(0)for Ni-Mn-In alloys.Combined with the strategies of reducing the negative contribution of magnetic en-tropy change(via the substitution of Cu for Mn)and introducing strong crystallographic texture(through directional solidification),an outstanding elastocaloric prototype alloy of Ni_(50)(Mn_(28.5)Cu_(4.5))(In_(14)Ga_(3))was fabricated experimentally.At room temperature,a huge△T_(ad)of-19 K and a large specific adiabatic temperature change of 67.8 K/GPa are obtained.The proposed first-principle-assisted framework opens up the possibility of efficiently tailoring△V/V_(0)to promote the design of advanced elastocaloric refrigerants.

On the micromechanism of superior strength and ductility synergy in a heterostructured Mg-2.77Y alloy

Heterostructured metals and alloys are a new class of materials in which mechanical behaviors between the heterogeneous regions are significantly different,and the mechanical properties of bulk materials are superior to the superposition of individual regions.In this paper,three distinct types of heterostructures were constructed in Mg-2.77Y(wt.%)alloy by applying simple thermomechanical processing.Namely,Type I:the non-recrystallized grains of several tens of microns were embedded in the micron-scaled recrystallized grains that were distributed along shear bands and dispersed near grain boundaries;Type II:the aggregations of micron-scaled recrystallized grains were surrounded by the non-recrystallized grains;Type II:the micron-scaled recrystallized grains dominated the microstructure,and the non-recrystallized regions with diameters of tens of micrometers were surrounded by those fine recrystallized grains.Mechanical tests showed that the material with type III heterostructure had the optimal combination of yield strength and uniform elongation.This is attributed to its remarkable hetero-deformation induced(HDI)strengthening and dislocation strengthening.At the initial stage of plastic deformation(engineering strain below 4%),the rapid accumulation of geometrically necessary dislocations(GNDs)at the interfaces between recrystallized and non-recrystallized regions and between neighboring recrystallized grains lead to the significant HDI strengthening.As deformation proceeded,the HDI strengthening effect gradually decreased,and the traditional dislocation strengthening that was caused by GNDs accumulation at grain boundaries became significant.In-situ electron back-scattered diffraction(EBSD)testing revealed that the non-basal slip in the non-recrystallized regions became more remarkable in the late stage of deformation,which improved ductility and strain hardening of the alloy.These findings provide new insight into the design of high-performance hexagonal close-packed structural materials by using the concept of HDI strengthening.

Microstructural and textural evolutions in multilayered Ti/Cu composites processed by accumulative roll bonding

Ti/Cu multilayered composites were fabricated via accumulative roll bonding(ARB). During codeformation of the constituent metals, the hard Ti layers necked preferentially and then fragmented with the development of shear bands. Transmission electron microscopy showed that with increasing ARB cycles, grains in Ti were significantly refined even though dynamic recrystallization has occurred. For Cu the significant grain refinement was only found within the shear banded region when the composite was processed after five ARB cycles. Due to the diffusion of Cu atoms into Ti at the heterophase interfaces, amorphization with a width less than 10 nm was identified even in the composite processed by one cycle. At higher ARB cycles, the width of amorphous region increased and intermetallic compounds CuTi appeared from the region. The lattice defects introduced at the heterophase interfaces under roll bonding was responsible for the formation of the nano-scaled compounds. X-ray diffraction showed that an abnormal {1120} fiber texture was developed in Ti layers, while significant brass-type textures were developed in Cu layers. Some orientations along the {1120} fiber favored the prismatic < a> slip for Ti.Tensile tests revealed the elevated strength without a substantial sacrifice of ductility in the composites during ARB. The unique mechanical properties were attributed to the significantly refined grains in individual metals, the good bonding between the constituent metals, as well as the development of an abnormal {1120} fiber texture in Ti layers.

Synergy effect of multi-strengthening mechanisms in FeMnCoCrN HEA at cryogenic temperature

High-entropy alloys(HEAs)have attracted great research interest owing to their good combination of high strength and ductility at both room and cryogenic temperatures.However,expensive raw materials are always added to overcome the strength-ductility trade-off at low temperatures,leading to an increased production cost for the cryogenically used alloys.In this work,a series of nitrogen-doped Fe Mn Co Cr HEAs have been processed by homogenization annealing,cold rolling and recrystallization annealing followed by water quenching.The microstructural evolution and mechanical properties of the alloys are studied systematically.The Fe_(49)Mn_(30)Co_(10)Cr_(10)N1alloy shows excellent mechanical properties at both 293 K and 77 K.Particularly,the yield and ultimate tensile strength of 1078 and 1630 MPa are achieved at the cryogenic temperature,respectively,while a satisfactory uniform elongation of 33.5%is maintained.The ultrahigh yield strength results from the microstructure refinement caused by the activation of athermal martensitic transformation and mechanical twinning that occur in the elastic regime together with the increased lattice friction due to the cryogenic environment.In the plastic regime,the dynamic Hall-Petch effect caused by twinning,martensitic transformation,and reverse transformation together with the high barrier to dislocation motion jointly contribute to the ultrahigh tensile strength.Simultaneously,the transformation induced plasticity(TRIP)and the twinning induced plasticity(TWIP)effects jointly contribute to the ductility.The design strategy for attaining superior mechanical properties at low temperatures,i.e.by adjusting stacking fault energy in the interstitial metastable HEAs,guides the development of high-performance and low-cost alloys for cryogenic applications.