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Rapid in situ alloying of CoCrFeMnNi high-entropy alloy from elemental feedstock toward high-throughput synthesis via laser powder bed fusion

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Frontiers of Mechanical Engineering 2023年第1期18卷 131-145页

作者： Bowen WANG Bingheng LU Lijuan ZHANG Jianxun ZHANG bobo LI Qianyu JI Peng luo Qian LIU School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049China National Innovation Institute of Additive Manufacturing Xi’an 710300China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China Institute of Materials China Academy of Engineering PhysicsMianyang 621908China

High-entropy alloys(HEAs)are considered alternatives to traditional structural materials because of their superior mechanical,physical,and chemical properties.However,alloy composition combinations are too numerous to explore.Finding a rapid synthesis method to accelerate the development of HEA bulks is imperative.Existing in situ synthesis methods based on additive manufacturing are insufficient for efficiently controlling the uniformity and accuracy of components.In this work,laser powder bed fusion(L-PBF)is adopted for the in situ synthesis of equiatomic CoCrFeMnNi HEA from elemental powder mixtures.High composition accuracy is achieved in parallel with ensuring internal density.The L-PBF-based process parameters are optimized;and two different methods,namely,a multi-melting process and homogenization heat treatment,are adopted to address the problem of incompletely melted Cr particles in the single-melted samples.X-ray diffraction indicates that HEA microstructure can be obtained from elemental powders via L-PBF.In the triple-melted samples,a strong crystallographic texture can be observed through electron backscatter diffraction,with a maximum polar density of 9.92 and a high ultimate tensile strength(UTS)of(735.3±14.1)MPa.The homogenization heat-treated samples appear more like coarse equiaxed grains,with a UTS of(650.8±16.1)MPa and an elongation of(40.2%±1.3%).Cellular substructures are also observed in the triple-melted samples,but not in the homogenization heat-treated samples.The differences in mechanical properties primarily originate from the changes in strengthening mechanism.The even and flat fractographic morphologies of the homogenization heat-treated samples represent a more uniform internal microstructure that is different from the complex morphologies of the triple-melted samples.Relative to the multi-melted samples,the homogenization heat-treated samples exhibit better processability,with a smaller composition deviation,i.e.,≤0.32 at.%.The two methods presented in this study are expected to ha

关键词： laser powder bed fusion(L-PBF) in situ alloying high-entropy alloys heat treatment rapid synthesis

Fine particulate matter(PM_(2.5)/PM_(1.0)) in Beijing,China: Variations and chemical compositions as well as sources

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Journal of Environmental Sciences 2022年第11期34卷 187-198页

作者： Lining luo Xiaoxuan Bai Shuhan Liu bobo Wu Wei Liu Yunqian Lv Zhihui Guo Shumin Lin Shuang Zhao Yan Hao Jiming Hao Kai Zhang Aihua Zheng Hezhong Tian State Key Laboratory of Environmental Simulation and Pollution Control School of EnvironmentBeijing Normal UniversityBeijing 100875China Center for Atmospheric Environmental Studies Beijing Normal UniversityBeijing 100875China School of Environment Tsinghua UniversityBeijing 100084China Department of Environmental Health Sciences School of Public Health University at Albany State University of New York One University Place RensselaerNY 12144USA Analysis and Testing Center Beijing Normal UniversityBeijing 100875China

Particulate matter(i.e.,PM_(1.0) and PM_(2.5)),considered as the key atmospheric pollutants,exerts negative effects on visibility,global climate,and human health by associated chemical compositions.However,our understanding of PM and its chemical compositions in Beijing under the current atmospheric environment is still not complete after witnessing marked alleviation during 2013–2017.Continuous measurements can be crucial for further air quality improvement by better characterizing PM pollution and chemical compositions in Beijing.Here,we conducted simultaneous measurements on PM in Beijing during 2018–2019.Results indicate that annualmean PM_(1.0) and PM_(2.5) concentrations were 35.49±18.61μg/m^(3) and 66.58±60.17μg/m^(3),showing a positive response to emission controls.The contribution of sulfate,nitrate,and ammonium(SNA)played an enhanced role with elevated PM loading and acted as the main contributors to pollution episodes.Discrepancies observed among chemical species between PM_(1.0) and PM_(2.5) in spring suggest that sand particles trend to accumulate in the range of 1–2.5μm.Pollution episodes occurred accompanied with southerly clusters and high formation of SNA by heterogeneous reactions in summer and winter,respectively.Results from positive matrix factorization(PMF)combined with potential source contribution function(PSCF)models showed that potential areas were seasonal dependent,secondary and vehicular sources became much more important compared with previous studies in Beijing.Our study presented a continuous investigation on PM and sources origins in Beijing,which provides a better understanding for further emission control as well as a reference for other cities in developing countries.

关键词： Fine particles Haze Chemical species Seasonal variation Source apportionment

Room-temperature ferroelectricity in magnetically ordered CoH2SeO4 flakes

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SCIENCE CHINA-MATERIALS 2024年第5期67卷 1654-1660页

作者： Chen, Luqiu Yu, Bing Shen, Yang Liu, Yifei Wang, Haonan Feng, Guangdi Zhu, Qiuxiang luo, Weidong Liu, Junming Wan, Jianguo Zhao, Qingbiao Tian, bobo Chu, Junhao Duan, Chungang East China Normal Univ Shanghai Ctr Brain inspired Intelligent Mat & Devi Key Lab Polar Mat & Devices MOE Shanghai 200241 Peoples R China East China Normal Univ Dept Elect Shanghai 200241 Peoples R China Zhejiang Lab Hangzhou 310000 Peoples R China Nanjing Univ Lab Solid State Microstruct Nanjing 210093 Peoples R China Nanjing Univ Innovat Ctr Adv Microstruct Nanjing 210093 Peoples R China Shanghai Jiao Tong Univ Sch Phys & Astron Key Lab Artificial Struct & Quantum Control Shanghai 200240 Peoples R China Wuhan Inst Technol Sch Chem & Environm Engn Wuhan 430205 Peoples R China Chinese Acad Sci Shanghai Inst Tech Phys State Key Lab Infrared Phys Shanghai 200083 Peoples R China Fudan Univ Inst Optoelect Shanghai 200433 Peoples R China Shanxi Univ Collaborat Innovat Ctr Extreme Opt Taiyuan 030006 Peoples R China

Here, we demonstrate the existence of magnetic ordering and sliding ferroelectricity in two-dimensional CoH2SeO4 multilayers. The experimental result reveals the antiferromagnetic order in powder sample, and first-principles calculation indicates the antiferromagnetic ground state with T-N approximate to 75 K in CoH2SeO4 single layer. The sliding ferroelectricity with an asymmetric triplet potential well is theoretically predicted and experimentally confirmed by 180 degrees-piezoelectric hysteresis loops, switchable domains and second harmonic generation signals in CoH2SeO4 multilayers. The vertically stacked ferroelectric capacitor shows both polarization and capacitance hysteresis loops. A ferroelectric transition temperature of similar to 370 K is obtained from the temperature-dependent dielectricity. The emergence of sliding ferroelectricity and anti-ferromagnetism points out a new route for obtaining low-dimensional multiferroic materials.

关键词： two-dimensional materials sliding ferroelectricity multiferroic materials TOTAL-ENERGY CALCULATIONS MULTIFERROICS

Extraordinary high-temperature mechanical properties in binder-free nanopolycrystalline WC ceramic

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Journal of Materials Science & Technology 2022年第2期97卷 169-175页

作者： Hongfeng Dong Baozhong Li bobo Liu Yang Zhang Lei Sun Kun luo Yingju Wu Mengdong Ma Bing Liu Wentao Hu Julong He Dongli Yu Bo Xu Zhisheng Zhao Yongjun Tian Center for High Pressure Science(CHiPS) State Key Laboratory of Metastable Materials Science and TechnologyYanshan UniversityQinhuangdao 066004China School of Materials Science and Engineering Shaanxi University of TechnologyHanzhong 723001China

From the perspective of high-temperature applications,materials with excellent high-temperature mechanical properties are always desirable.The present work demonstrates that the binder-free nanopolycrystalline WC ceramic with an average grain size of 103 nm obtained by high-pressure and hightemperature sintering exhibits excellent mechanical properties at both room temperature and high temperature up to 1000℃.Specifically,the binder-free nanopolycrystalline WC ceramic still maintains a considerably high Vicker hardness H_(V)of 23.4 GPa at 1000℃,which is only 22%lower than the room temperature H_(V).This outstanding thermo-mechanical stability is superior to that of typical technical ceramics,e.g.SiC,Si_(3)N_(4),Al_(2)O_(3),etc.Nanocrystalline grains with many dislocations,numerous low-energy,highly stableΣ2 grain boundaries,and a relatively low thermal expansion coefficient,are responsible for the observed outstanding high-temperature mechanical properties.

关键词： Binder-free nanopolycrystalline WC High-pressure and high-temperature synthesis High-temperature mechanical properties Dislocation Σ2 Grain boundary

天冬氨酸对亚铁混凝剂絮体结构及磷酸盐去除效果的影响

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环境工程学报 2022年第6期16卷 1815-1822页

作者：罗义赵丙昊邢波波俞文正河北建筑工程学院张家口075000 中国科学院生态环境研究中心环境水质学国家重点实验室北京100085

铁混凝剂广泛应用于水处理领域,形成的絮体大小、形态和结晶度直接决定其混凝效果。然而小分子有机物对混凝的影响机制尚不清楚。本研究以FeSO_(4)作为混凝剂,通过添加特定的小分子有机物(分子质量<1 000 Da)天冬氨酸,研究了天冬氨酸对... 详细信息

铁混凝剂广泛应用于水处理领域,形成的絮体大小、形态和结晶度直接决定其混凝效果。然而小分子有机物对混凝的影响机制尚不清楚。本研究以FeSO_(4)作为混凝剂,通过添加特定的小分子有机物(分子质量<1 000 Da)天冬氨酸,研究了天冬氨酸对絮体生长过程及其产物的影响。结果表明,天冬氨酸通过影响金属的水解和纳米颗粒的性质进而影响其混凝性能。在pH=7时,天冬氨酸的存在延缓了絮体的初始生长时间,但增大了絮凝体的最大粒径(从0.05μm大小的碎片和小球状参杂的絮体变化至0.1μm的褶皱状絮体)和磷酸盐的去除率。当添加0.4 mmol·L^(-1)的天冬氨酸时,纤铁矿(γ-FeOOH)为絮体的主要成分,这可能少量的天冬氨酸存在时,体系中部分亚铁离子会被包裹,Fe(OH)_(2)纳米颗粒由于铁化合物的饱和快速形成,随后作为晶核生长;Fe(OH)_(2)纳米颗粒表面通过被氧化转化成三价铁,最终形成γ-FeOOH;当添加天冬氨酸大于0.4 mmol·L^(-1)时,絮体的主要成分为四方纤铁矿(β-FeOOH),此时部分亚铁离子被完全包裹,剩余的亚铁离子被氧化成三价铁后形成β-FeOOH。经过天冬氨酸诱导后形成的絮体对磷酸盐的去除率均增加了1.57倍左右,处理后的磷酸盐浓度降低到了0.02 mg·L^(-1),且在添加1.5 mmol·L^(-1)天冬氨酸时絮体的尺寸最大,此时的絮体更加容易沉降分离。

关键词：天冬氨酸絮体纤铁矿和四方纤铁矿除磷

基于PSO-LSSVM球磨机负荷参数预测及监测系统开发

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噪声与振动控制 2022年第4期42卷 144-151页

作者：罗小燕黄耀锋李波波刘吉顺江西理工大学机电工程学院江西赣州341000 江西省矿冶机电工程技术研究中心江西赣州341000

针对球磨机筒体振动信号中存在非线性、非平稳性及环境噪声强等问题,提出一种基于粒子群优化最小二乘支持向量机(PSO-LSSVM)球磨机负荷参数(填充率和料球比)预测方法,并开发基于LabVIEW的球磨机负荷参数监测系统。通过粒子群(PSO)优化... 详细信息

针对球磨机筒体振动信号中存在非线性、非平稳性及环境噪声强等问题,提出一种基于粒子群优化最小二乘支持向量机(PSO-LSSVM)球磨机负荷参数(填充率和料球比)预测方法,并开发基于LabVIEW的球磨机负荷参数监测系统。通过粒子群(PSO)优化最小二乘支持向量机(LSSVM)算法中的正则化参数y和核函数宽度,简化求解过程,提高模型训练速度。以球磨机筒体振动信号的Hilbert-边际谱样本熵为输入,以球磨机筒体内部的填充率和料球比为输出,建立基于PSO-LSSVM的磨机负荷参数预测模型。与LSSVM预测结果比较,该模型的预测精度较高,填充率平均绝对误差降低0.05、平均绝对百分误差降低8.09%;料球比平均绝对误差降低0.04、平均绝对百分误差降低2.76%。在线测试结果表明该在线监测系统准确率为64.37%,且系统运行一次的平均时间为45 s,可实现球磨机负荷参数的实时预测。

关键词：振动与波球磨机 LSSVM PSO LabVIEW 负荷参数

Prader-Willi综合征的临床实践指南

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中华医学遗传学杂志 2020年第3期37卷 318-323页

作者：无李川谢波波沈亦平罗飞宏中华医学会医学遗传学分会遗传病临床实践指南撰写组广西壮族自治区妇幼保健院遗传代谢中心实验室上海交通大学医学院附属上海儿童医学中心内分泌代谢科、医学遗传科美国波士顿儿童医院遗传及基因组部复旦大学附属儿科医院内分泌遗传代谢科

Prader-Willi综合征(Prader-Willi syndrome,PWS)是首个被阐明的以基因组印记异常为致病机理的多系统遗传病。PWS的临床表现因年龄而异。胎儿期表现为胎动少;新生儿期主要表现为肌张力低下、哭声弱、吸吮无力、喂养困难等;婴幼儿期表现... 详细信息

Prader-Willi综合征(Prader-Willi syndrome,PWS)是首个被阐明的以基因组印记异常为致病机理的多系统遗传病。PWS的临床表现因年龄而异。胎儿期表现为胎动少;新生儿期主要表现为肌张力低下、哭声弱、吸吮无力、喂养困难等;婴幼儿期表现为生长发育及语言运动发育迟缓;儿童期表现为矮胖、小手足和认知功能障碍等;青春期以身高明显不足、肥胖、性腺发育不良、异常行为、学习困难等为主要特征。患者因饮食过度导致的病态肥胖是影响预后的主要因素。早期诊断、早期干预,对于改善其生活质量、预防严重的并发症和延长寿命具有重要的意义。本指南主要介绍PWS的临床症状、疾病发展过程、发病机制、分子诊断以及遗传咨询等内容,为临床医师对该病进行早期识别、合理干预和遗传咨询提供参考。

关键词： Prader-Willi综合征印记遗传病实践指南

Research on High Temperature and High Density White Oil Based Drilling Fluid and Its Application in Well 201H7-6

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Open Journal of Yangtze Oil and Gas 2019年第3期4卷 174-182页

作者： bobo Qin Yidi Wang Chunzhi luo Gang Liu College of Chemistry and Environmental Engineering Yangtze UniversityJingzhouChina

As the depth and horizontal length of shale gas development wells increase,the requirement for the temperature resistance and the ability of the drilling fluids to stabilize the shale formation becomes higher.A new type of high temperature and high density white oil based drilling fluid system has been developed in laboratory.Research shows that the drilling fluid system has good rheological property,low filtration loss,strong anti-debris pollution capability and good plugging performance at high temperature and high density.The system has been successfully applied in the 201H7-6 well.Application results show that the drilling fluid rheology,high temperature and high pressure fluid loss and demulsification voltage meet the field requirements.The drilling fluid performance is stable in drilling an 1800 m horizontal section,and no stuck or shale swelling and wellbore collapsing are induced.It is the first well drilled successfully with domestic white oil-based drilling fluid in Zigong Region.It also sets several new records including the deepest well,the shortest drilling cycle,and the fastest drilling speed in that region,which provides valuable experience for the future drilling activities.

关键词： Oil-Based Drilling Fluid Demulsification Voltage Rheology Fluid Loss,Inhibition Pollution Plugging

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深层低渗凝析气藏气驱适应性研究

油气藏评价与开发 2024年第3期14卷 324-332,F0002页

作者：李中超齐桂雪罗波波许寻陈华中国石化酸性气开发重点实验室河南濮阳457000 中国石化中原油田分公司勘探开发研究院河南濮阳457000 中国石化中原油田分公司河南濮阳457000

针对深层低渗凝析气藏由衰竭开采转变为气驱开发过程中适应性不明确的问题,综合采用PVT(地层流体高压物性)分析仪、长岩心驱替物理模拟技术和数值模拟计算方法,开展了一系列评价研究。通过对比分析注CO_(2)、天然气(伴生气、CH_(4))、N_... 详细信息

针对深层低渗凝析气藏由衰竭开采转变为气驱开发过程中适应性不明确的问题,综合采用PVT(地层流体高压物性)分析仪、长岩心驱替物理模拟技术和数值模拟计算方法,开展了一系列评价研究。通过对比分析注CO_(2)、天然气(伴生气、CH_(4))、N_(2)对凝析气体系高压物性影响与提高凝析油采出程度情况,明确了深层低渗凝析气藏气驱的适应性。实验结果表明:CO_(2)在凝析油中的溶解度和溶解气油比最大,具有较强降低凝析气藏饱和压力和露点压力的特点,提高凝析油采出程度的效果最佳。同时,采用长岩心物理模拟技术针对CO_(2)驱进行了注入时机、注入方式、注气速度优化研究,明确了在露点压力以上脉冲式注气效果更好,为注气开发技术政策及现场方案的实施提供数据支撑。

关键词：凝析气藏深层低渗注气介质气驱适应性参数优化