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Journal of Magnesium and Alloys 2022年第5期10卷 1235-1241页

作者： Xin Wang dikai guan Department of Materials Science and Engineering University of SheffieldSheffield S13JDUK

The nucleation,grain growth of 34 coarse grains during annealing were tracked using a quasi-in-situ EBSD method.These 34 coarse grains had different orientations and most grains were non-basal orientated.No preferable grain growth or special types of grain boundaries were identified.Only 9 coarse grains nucleated from deformed grain boundaries due to initial large grain size and limited grain boundary volume fraction.The main nucleation site of 34 coarse grains was dislocation cells or subgrains in deformed grain interiors.Their recrystallisation behaviour can be illustrated by abnormal subgrain growth(As GG)rarely reported in Mg alloys.The coarse basal grains showed no growth advantage in terms of grain size or number over other non-basal grains,leading to a weak basal texture in AZ31B alloy.

关键词： Magnesium alloy EBSD Annealing Recrystallisation Grain growth

Martensitic twinning transformation mechanism in a metastable IVB element-based body-centered cubic high-entropy alloy with high strength and high work hardening rate

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Journal of Materials Science & Technology 2022年第29期124卷 217-231页

作者： Yuhe Huang Junheng Gao Vassili Vorontsov dikai guan Russell Goodall David Dye Shuize Wang Qiang Zhu W.Mark Rainforth Iain Todd Department of Materials Science and Engineering University of SheffieldSheffield S13JDUnited Kingdom Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen518055China Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Department of Materials Royal School of MinesImperial College LondonLondon SW72BPUnited Kingdom

Realizing high work hardening and thus elevated strength–ductility synergy are prerequisites for the practical usage of body-centered-cubic high entropy alloys(BCC-HEAs).In this study,we report a novel dynamic strengthening mechanism,martensitic twinning transformation mechanism in a metastable refractory element-based BCC-HEA(TiZrHf)Ta(at.%)that can profoundly enhance the work hardening capability,leading to a large uniform ductility and high strength simultaneously.Different from conventional transformation induced plasticity(TRIP)and twinning induced plasticity(TWIP)strengthening mechanisms,the martensitic twinning transformation strengthening mechanism combines the best characteristics of both TRIP and TWIP strengthening mechanisms,which greatly alleviates the strengthductility trade-off that ubiquitously observed in BCC structural alloys.Microstructure characterization,carried out using X-ray diffraction(XRD)and electron back-scatter diffraction(EBSD)shows that,upon straining,α”(orthorhombic)martensite transformation,self-accommodation(SA)α”twinning and mechanicalα”twinning were activated sequentially.Transmission electron microscopy(TEM)analyses reveal that continuous twinning activation is inherited from nucleating mechanical{351}type I twins within SA“{351}”typeⅡtwinnedα”variants on{351}twinning plane by twinning transformation through simple shear,thereby accommodating the excessive plastic strain through the twinning shear while concurrently refining the grain structure.Consequently,consistent high work hardening rates of 2–12.5 GPa were achieved during the entire plastic deformation,leading to a high tensile strength of 1.3 GPa and uniform elongation of 24%.Alloy development guidelines for activating such martensitic twinning transformation strengthening mechanism were proposed,which could be important in developing new BCC-HEAs with optimal mechanical performance.

关键词： Metastable high entropy alloy Work hardening rate Martensitic transformation Self-accommodating martensite Twinning transformation

Underlying slip/twinning activities of Mg-xGd alloys investigated by modified lattice rotation analysis

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Journal of Magnesium and Alloys 2023年第3期11卷 998-1015页

作者： Biaobiao Yang Chenying Shi Xianjue Ye Jianwei Teng Ruilin Lai Yujie Cui dikai guan Hongwei Cui Yunping Li Akihiko Chiba State Key Lab for Powder Metallurgy Central South UniversityChangsha 410083China Institute for Materials Research Tohoku UniversitySendai 980-8577Japan Department of Materials Science and Engineering University of SheffieldMappin StreetSheffield S13JDUnited Kingdom School of Materials Science and Engineering Shandong University of TechnologyZibo 255000China

The inconsistencies regarding the fundamental correlation between Gd content and slip(twinning)activities of Mg alloys appeal further investigations.However,the traditional slip dislocations analysis by TEM is time-consuming,and that by SEM/EBSD cannot recognize the partial slip modes.These urge a more efficient and comprehensive approach to easily distinguish all potential slip modes occurred concurrently in alloy matrix.Here we report a modified lattice rotation analysis that can distinguish all slip systems and provide statistical results for slip activities in Mg alloy matrix.Using this method,the high ductility of Mg-Gd alloy ascribed to the enhanced non-basal slips,cross-slip,and postponed twinning activities by Gd addition is quantitatively clarified.

关键词： Mg-Gd alloy Non-basal slips Postponed twinning Grain boundary segregation Modified lattice rotation analysis

微量Er对Mg-Nd-Zn-Zr合金显微组织与力学性能的影响

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热加工工艺 2012年第2期41卷 1-4页

作者：梁叔全陈亮官迪凯陈涛中南大学材料科学与工程学院湖南长沙410083

利用光学显微镜、扫描电镜、透射电镜、能谱仪、X射线衍射分析及力学性能测试,研究了稀土元素Er对Mg-Nd-Zn-Zr合金铸态显微组织及力学性能的影响。结果表明:在Mg-Nd-Zn-Zr合金中添加0.5wt%Er后,元素Er主要以白色小颗粒形貌分布在晶间,... 详细信息

利用光学显微镜、扫描电镜、透射电镜、能谱仪、X射线衍射分析及力学性能测试,研究了稀土元素Er对Mg-Nd-Zn-Zr合金铸态显微组织及力学性能的影响。结果表明:在Mg-Nd-Zn-Zr合金中添加0.5wt%Er后,元素Er主要以白色小颗粒形貌分布在晶间,合金达到峰值时效的时间更短,且有大量细小的相均匀析出,时效强化效果更好;加入Er后,合金抗拉强度、屈服强度和伸长率分别达到283.4、170.2 MPa和4%;在Mg-Nd-Zn-Zr-Er合金室温拉伸断口中有高度不一的解理台、撕裂棱和少量韧窝,韧窝中的颗粒物主要含Er、Nd,说明该合金具有较好的塑性;Er的加入并没有改变合金的断裂方式,两种合金时效态都以准解理断裂为主。

关键词：稀土Er Mg-Nd-Zn-Zr合金显微组织力学性能

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铝合金阳极性能影响因素的研究进展

热加工工艺 2009年第16期38卷 3-7页

作者：梁叔全官迪凯张勇刘荣中南大学材料科学与工程学院湖南长沙410083

在铝合金阳极的活化机理的基础上,探讨了合金元素(稀土金属)、热处理、轧制工艺以及缓蚀剂等方面对铝阳极性能的影响,综述了国内外铝合金阳极的发展情况,并指出了铝阳极材料的发展方向和前景。

关键词：铝合金阳极活化合金元素缓蚀剂

果品主要真菌毒素污染检测、风险评估与控制研究进展

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中国农业科学 2017年第2期50卷 332-347页

作者：李志霞聂继云闫震张晓男关棣锴沈友明程杨中国农业科学院果树研究所/农业部果品质量安全风险评估实验室(兴城)

果品在生产、贮运过程中易发生真菌性病害,不但可引起腐烂或腐败,带来严重的经济损失,部分霉菌还可能产生真菌毒素对人体健康造成潜在危害。真菌毒素是一类由丝状真菌在适宜条件下产生的有毒次级代谢产物,是继农药残留、重金属污染后,... 详细信息

果品在生产、贮运过程中易发生真菌性病害,不但可引起腐烂或腐败,带来严重的经济损失,部分霉菌还可能产生真菌毒素对人体健康造成潜在危害。真菌毒素是一类由丝状真菌在适宜条件下产生的有毒次级代谢产物,是继农药残留、重金属污染后,影响果品质量安全的又一类关键风险因子,具有强毒性。大量研究表明,真菌毒素可致DNA损伤,低浓度下即可对人和动物健康造成危害,使肝脏、肾脏和胃肠道发生病变,并且可致癌、致畸、致突变等,研究真菌毒素的污染状况,进行精准检测、风险评估和控制,对于果品质量安全研究具有重要意义。展青霉素(Patulin,PAT)、黄曲霉毒素(Aflatoxins,AF)、链格孢毒素(Alternaria toxins)和赭曲霉毒素A(Ochratoxin A,OTA)是存在于果品中的主要真菌毒素种类,国际癌症研究机构(IARC)分别将PAT、AFB1、AFM1和OTA列为第3类、1类、2B类和2B类致癌物质。通常果品中检出的真菌毒素含量极低,因此对检测方法的要求较高,目前主要的分析方法有薄层色谱法、高效液相色谱(含质谱联用)技术、气相色谱(含质谱联用)技术、毛细管电泳技术等,但往往由于化学结构和性质各异,无法采用一种标准方法完成对所有真菌毒素的定量测定。因此,筛选准确、高效、快速的检测方法也是该领域当今的研究热点。迄今为止,已有80个国家和地区制定了果品中真菌毒素的限量标准来保护消费者健康,但均未涉及链格孢霉毒素。许多国家均不同程度地开展了真菌毒素风险评估研究,基于毒理学数据的评估结果表明,大多情形下通过果品摄入的真菌毒素水平极低,不会对居民健康产生危害。果品中的真菌毒素可采用化学、物理、生物等方法进行防治、降解和控制,但无法将被真菌毒素污染后产品中的毒素完全脱除,果品中真菌毒素污染重在"防"而非"除"。本文从果品中主要真菌毒素的种类、污染状况、毒性、检测方法、限量标准、风险评估及控制技术等方面进行概述,同时,对果品中真菌毒素的重点研究方向进行了展望,以期为该领域研究者提供参考。

关键词：果品真菌毒素展青霉素黄曲霉毒素链格孢毒素赭曲霉毒素A 风险评估