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Abnormal grain growth induced byδ→γphase transformation in Fe-based shape memory alloys

Journal of Materials Science & Technology 2024年第5期172卷 196-201页

作者： Huabei Peng Liqiu Yong Gaixia Wang jiazhen yan Bing Xu Yuhua Wen School of Mechanical Engineering Sichuan UniversityChengdu 610065China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610041China

Grain boundaries,including low-angle,high-angle,and coinci-dence boundaries,are intrinsic interfaces in polycrystalline materi-als.During heat-treatment at sufficiently high temperatures,grain boundary migration occurs because the grain boundaries are ther-modynamically unstable.Consequently,grain growth occurs due to a decrease in grain boundary area after heat-treatment[1].In general,there are two types of grain growth:normal grain growth,where grains grow uniformly,and abnormal grain growth,where one or a few grains selectively grow and engulf surround-ing smaller grains,leading to the formation of large grains,some-times several millimeters or greater in size[2].The classical tech-nique to achieve abnormal grain growth is the strain-annealing method,which involves subjecting the material to a small strain followed by annealing[3,4].This method has been reported to ob-tain single-crystal wires or plates[1].Additionally,abnormal grain growth can be achieved by plastic straining at high temperatures,resulting in the fabrication of large grains or single crystals[5].However,the above methods are not applicable to components with complicated shapes due to the inevitable deformation pro-cess.Recently,Omori et al.developed a simply method of abnor-mal grain growth to fabricate ultra-large grains,even single crys-tals,in Cu-Al-Mn[1],Fe-Mn-Al-Ni[2],and Fe-Mn-Al-Ni-Cr[6]al-loys.This method involves applying cyclic heat treatment between a high temperature BCC single-phase region and a low tempera-ture BCC+FCC two-phase region[1,2,6-12].Note that the cyclic heat treatment resulted in the formation of BCC sub-grain struc-tures responsible for abnormal grain growth[1,2,6-12].In addition,yang et al.reported that abnormal grain growth occurred at above 900℃,and large-grains,even single crystals,were obtained only through annealing cast Cu-based polycrystalline alloys contained coherent nano-particles[13,14].Notably,the cyclic heat treatment and annealing cast alloys are deformation-free and much simpler than the strain-anne

关键词： grain alloys deformation

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Effect of cyclic heat treatment on abnormal grain growth in Fe-Mn-Al-based shape memory alloys with different Ni contents

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Journal of Materials Science & Technology 2023年第22期153卷 8-21页

作者： Huabei Peng Liqiu Yong yang Zuo jiazhen yan Hui Wang Yuhua Wen School of Mechanical Engineering Sichuan UniversityChengdu 610065China Key Laboratory of Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China Interdisciplinary Materials Research Center Institute for Advanced StudyChengdu UniversityChengdu 610106China

Cyclic heat treatment that can continuously promote abnormal grain growth is widely used for the prepa-ration of single-crystal Fe-Mn-Al-based shape memory alloys.However,it takes a long time to prepare large-size Fe-Mn-Al-based alloy single crystals via the reported cyclic heat treatments.Meanwhile,the long-time cyclic heat treatment at high temperatures leads to the development of defects including oxidation and a decrease in Mn,which would deteriorate superelasticity in the Fe-Mn-Al-based shape memory alloys.To shorten the fabrication time of single crystals,the effect of the cyclic heat treatment process on the abnormal grain growth in the Fe-Mn-Al-based alloys with different Ni contents was systematically investigated.It is found that the abnormal grain growth of Fe-Mn-Al-based alloys was not significantly affected by the Ni contents(within 2.1 at.%-6.2 at.%).In addition,the abnormal grain growth could be promoted by 1-2℃ min^(-1) cooling rate,high solution temperature,and multiple cycles,while it was insensitive to other processes including heating rate,dual-phase time as well as long-time solution treat-ment.These findings can guide optimizing the fabrication process of single crystals by cyclic heat treat-ment.Finally,the Fe_(41.9)Mn_(37.8)Al_(14.1) Ni_(6.2) single crystal prepared by the optimized cyclic heat treatment showed a recoverable strain of about 4%.

关键词： Cyclic heat treatment Ni content Abnormal grain growth Fe-Mn-Al-based shape memory alloy Superelasticity

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Deformation-induced interfacial-twin-boundary ω-phase in an Fe_(48)Mn_(37)Al_(15) body-centered cubic metastable alloy

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Journal of Materials Science & Technology 2023年第15期146卷 252-258页

作者： Huabei Peng Xiao yang Lixin Sun Liqiu Yong jiazhen yan Jinyong Zhang Bingnan Qian Yuhua Wen School of Mechanical Engineering Sichuan UniversityChengdu 610065China School of Mechanical Engineering Hebei University of TechnologyTianjin 300401China State Key Laboratory of Materials Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China School of Materials and Physics China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Innovation Center NPU ChongqingChongqing 401135China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China

Omega(ω)phase has a trigonal or hexagonal crystal structure and was first discovered inβ-type Ti-Cr alloys[1].Since then,theω-phase has been widely reported in numerous group IV transition metal(Ti,Ta,Hf,and Zr)based alloys[2–9].The morphologies ofω-phase could be particle-like(athermalω-phase)[10],ellipsoidal or cuboidal after aging(isothermalω-phase)[11],and plate-like after deformation(stress-relatedω-phase)[12].Amongst,the stressrelatedω-phase is usually located at the twinning boundary,thus also called interfacial-twin-boundary-ω(ITB-ω)phase.The formation of the ITB-ωphase is considered to be related to the formation of{112}bccmechanical twin(i.e.,{112}bcc twin)in bodycentered cubic(BCC)metals and alloys[13].

关键词： alloys alloy deformation

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激光选区熔化生物医用Ti-6Al-4V合金的弯曲疲劳行为

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焊接学报 2024年第4期45卷 57-64,I0006页

作者：王群屈蕴韬张幖张玉鲜李锐李宁颜家振四川大学机械工程学院成都610065 成都科宁达材料有限公司成都610100

分析了SLM Ti-6Al-4V合金的弯曲疲劳行为及相应的微观组织和断口形貌,设置与SLM试样化学成分相同的轧制态Ti-6Al-4V合金进行对比研究.采用X射线衍射(XRD)、结合电子背散射衍射(EBSD)的扫描电子显微镜(SEM)对合金的微观组织进行分析.结... 详细信息

分析了SLM Ti-6Al-4V合金的弯曲疲劳行为及相应的微观组织和断口形貌,设置与SLM试样化学成分相同的轧制态Ti-6Al-4V合金进行对比研究.采用X射线衍射(XRD)、结合电子背散射衍射(EBSD)的扫描电子显微镜(SEM)对合金的微观组织进行分析.结果表明,三点弯曲疲劳裂纹起始于准解理断裂表面附近的应力集中,随后向内扩展.SLM成形Ti-6Al-4V合金的弯曲疲劳寿命高于轧制成形Ti-6Al-4V合金,SLM Ti-6Al-4V合金内部孔洞缺陷导致表面附近应力集中,促进疲劳裂纹形核;而SLM Ti-6Al-4V合金中随机取向的α+β晶粒、二次裂纹和孔洞延缓了裂纹扩展,提高了疲劳寿命.对于轧制态Ti-6Al-4V合金,由大量近似取向α晶粒组成的宏观区引起应力集中,形成微裂纹,导致疲劳裂纹形核,而且宏观区对裂纹扩展的阻碍作用较小,不利于材料的疲劳寿命.

关键词：激光选区熔化 Ti-6Al-4V合金微观组织弯曲疲劳裂纹扩展

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Grain boundary character and stress corrosion cracking behavior of Co-Cr alloy fabricated by selective laser melting

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Journal of Materials Science & Technology 2021年第34期93卷 244-253页

作者： Xin Dong Ning Li yanan Zhou Huabei Peng Yuntao Qu Qi Sun Haojiang Shi Rui Li Sheng Xu jiazhen yan School of Mechanical Engineering Sichuan UniversityChengdu 610065China Chengdu Keningda Materials Co. ChinaChengdu 610065China College of Stomatology Cuangxi Medical UniversityNanning 532201China

In this work,we used the selective laser melting(SLM)fabricated Co-Cr alloy with prominent residual strain,extremely non-equilibrium microstructures,and low stacking fault energy as a precursor to fabricate materials with the optimal grain boundary character distribution.The grain boundary engineering(GBE)of the Co-Cr alloy was achieved by a simple heat treatment of the SLM-fabricated Co-Cr alloy.The obtained GBE Co-Cr alloy exhibited 81.47%of special grain boundaries(∑3^(n)n=1,2,3),while it substantially disrupted the connectivity of the random high-angle boundaries,successfully reducing the propensity of intergranular degradation.Slow strain rate tests(SSRTs)showed that the GBE Co-Cr alloy possessed lower stress corrosion cracking(SCC)susceptibility and higher ductility in the corrosive environment(0.9%Na Cl solution)than in the air.The high fraction of special boundaries,coupled with the stress-induced martensitic transformation(SIMT)in the GBE Co-Cr alloy yielded these results,which unique and rarely simultaneously satisfied for common structural materials.The current"SLM induced GBE strategy"offers a novel approach towards customized GBE materials with high SCC resistance and ductility in the corrosive environment,shedding new light on developing high-performance structural materials.

关键词： Grain boundary engineering Selective laser melting Co-Cr alloy Stress corrosion cracking Ductility

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Impact of next-generation sequencing on antimicrobial treatment in immunocompromised adults with suspected infections

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World Journal of Emergency Medicine 2024年第2期15卷 105-110页

作者： Jia Li jiazhen Luo Tao Hu Ling Cheng Weiwei Shang Li yan Department of Intensive Care Unit Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Department of Emergency Medicine Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Tongji Medical College Huazhong University of Science and TechnologyWuhan 430030China Department of Geriatrics Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China

BACKGROUND:Prompt pathogen identification can have a substantial impact on the optimization of antimicrobial treatment.The objective of the study was to assess the diagnostic value of next-generation sequencing(NGS)for identifying pathogen and its clinical impact on antimicrobial intervention in immunocompromised patients with suspected infections.METHODS:This was a retrospective study.Between January and August 2020,47 adult immunocompromised patients underwent NGS testing under the following clinical conditions:1)prolonged fever and negative conventional cultures;2)new-onset fever despite empiric antimicrobial treatment;and 3)afebrile with suspected infections on imaging.Clinical data,including conventional microbial test results and antimicrobial treatment before and after NGS,were collected.Data were analyzed according to documented changes in antimicrobial treatment(escalated,no change,or deescalated)after the NGS results.RESULTS:The median time from hospitalization to NGS sampling was 19 d.Clinically relevant pathogens were detected via NGS in 61.7% of patients(29/47),more than half of whom suffered from fungemia(n=17),resulting in an antimicrobial escalation in 53.2% of patients(25/47)and antimicrobial de-escalation in 0.2% of patients(1/47).Antimicrobial changes were mostly due to the identification of fastidious organisms such as Legionella,Pneumocystis jirovecii,and Candida.In the remaining three cases,NGS detected clinically relevant pathogens also detected by conventional cultures a few days later.The antimicrobial treatment was subsequently adjusted according to the susceptibility test results.Overall,NGS changed antimicrobial management in 55.3%(26/47)of patients,and conventional culture detected clinically relevant pathogens in 14.9% of the patients(7/47).CONCLUSION:With its rapid identification and high sensitivity,NGS could be a promising tool for identifying relevant pathogens and enabling rapid appropriate treatment in immunocompromised patients with suspected infections.

关键词： Immunocompromised patients Next-generation sequencing Antimicrobial management

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Temporal and spatial variation and prediction of water yield and water conservation in the Bosten Lake Basin based on the PLUS-InVEST model

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Journal of Arid Land 2024年第6期16卷 852-874页

作者： CHEN jiazhen KASIMU Alimujiang REHEMAN Rukeya WEI Bohao HAN Fuqiang ZHANG yan School of Geography and Tourism Xinjiang Normal UniversityUrumqi 830054China Xinjiang Key Laboratory of Lake Environment and Resources in Arid Zone Urumqi 830054China School of Geography and Tourism Shaanxi Normal UniversityXi'an 710062China

To comprehensively evaluate the alterations in water ecosystem service functions within arid watersheds,this study focused on the Bosten Lake Basin,which is situated in the arid region of Northwest China.The research was based on land use/land cover(LULC),natural,socioeconomic,and accessibility data,utilizing the Patch-level Land Use Simulation(PLUS)and Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)models to dynamically assess LULC change and associated variations in water yield and water conservation.The analyses included the evaluation of contribution indices of various land use types and the investigation of driving factors that influence water yield and water conservation.The results showed that the change of LULC in the Bosten Lake Basin from 2000 to 2020 showed a trend of increasing in cultivated land and construction land,and decreasing in grassland,forest,and unused land.The unused land of all the three predicted scenarios of 2030(S1,a natural development scenario;S2,an ecological protection scenario;and S3,a cultivated land protection scenario)showed a decreasing trend.The scenarios S1 and S3 showed a trend of decreasing in grassland and increasing in cultivated land;while the scenario S2 showed a trend of decreasing in cultivated land and increasing in grassland.The water yield of the Bosten Lake Basin exhibited an initial decline followed by a slight increase from 2000 to 2020.The areas with higher water yield values were primarily located in the northern section of the basin,which is characterized by higher altitude.Water conservation demonstrated a pattern of initial decrease followed by stabilization,with the northeastern region demonstrating higher water conservation values.In the projected LULC scenarios of 2030,the estimated water yield under scenarios S1 and S3 was marginally greater than that under scenario S2;while the level of water conservation across all three scenarios remained rather consistent.The results showed that Hejing County is an important water conservation func

关键词： PLUS model InVEST model Bosten Lake Basin water yield water conservation land-use simulation Geodetector

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Al_2O_3陶瓷Ti+Nb/Mo金属化对其与Kovar合金钎焊连接的组织和力学性能的影响

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焊接学报 2018年第9期39卷 45-48,131页

作者：辛成来李宁颜家振四川大学制造科学与工程学院成都610065

采用磁控溅射在Al_2O_3陶瓷表面沉积了Ti+Nb/Mo金属层,实现了氧化铝陶瓷的金属化,并通过电镀镍提高了金属化效果.采用AgCu28钎料,实现了金属化Al_2O_3陶瓷与Kovar合金的可靠连接.通过扫描电子显微镜和能谱观察了钎缝的微观组织.结果表明... 详细信息

采用磁控溅射在Al_2O_3陶瓷表面沉积了Ti+Nb/Mo金属层,实现了氧化铝陶瓷的金属化,并通过电镀镍提高了金属化效果.采用AgCu28钎料,实现了金属化Al_2O_3陶瓷与Kovar合金的可靠连接.通过扫描电子显微镜和能谱观察了钎缝的微观组织.结果表明,钎料与母材发生了明显的界面反应.Cu元素扩散进入Kovar合金,同时Ni元素扩散进入钎料的富铜区,从而促进AgCu/Kovar连接界面的形成;金属化层在Al_2O_3/AgCu钎料界面处,起到了关键作用,其中铌可以抑制脆性化合物形成,缓解残余应力.金属化层镀镍后,钎缝中AgCu共晶区明显,且钎缝较宽,对提高镀镍试样的钎焊接头强度有一定作用.

关键词：氧化铝陶瓷金属化钎焊磁控溅射

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NiTi+Ni钎料真空钎焊SiC陶瓷的微观组织及性能

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热加工工艺 2023年第19期52卷 20-23页

作者：刘自豪颜家振李宁石浩江白冬四川大学机械工程学院四川成都610065

SiC作为潜在的下一代核反应堆包壳材料,实现其稳定可靠的连接是SiC基包壳管投入实际工程应用的重要一环。使用镍含量为55at%的NiTi粉和Ni粉混合膏状钎料(NiTi+5Ni钎料)在1350℃保温10min的工艺下实现了SiC陶瓷的连接。结果表明:焊缝界... 详细信息

SiC作为潜在的下一代核反应堆包壳材料,实现其稳定可靠的连接是SiC基包壳管投入实际工程应用的重要一环。使用镍含量为55at%的NiTi粉和Ni粉混合膏状钎料(NiTi+5Ni钎料)在1350℃保温10min的工艺下实现了SiC陶瓷的连接。结果表明:焊缝界面区域组织为TiC连续反应层;中心区域基体组织为δ-Ni_(2)Si+Ni_(3)Si_(2)共析组织,其中弥散分布着大量的TiC颗粒。接头平均室温剪切强度可达125MPa,断裂位于靠近界面的SiC陶瓷内部。界面处TiC与SiC之间良好的晶格匹配度以及焊缝中心区域的TiC颗粒对接头热残余应力的缓解,提升了接头的力学性能。

关键词：钎焊镍基钎料 SiC陶瓷微观组织力学性能

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Ni基钎料成分优化对SiC_(f)/SiC复合陶瓷真空钎焊接头微观形貌的影响

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核动力工程 2023年第S1期44卷 181-187页

作者：石浩江张瑞谦颜家振李鸣刘自豪白冬何勇吕俊男中国核动力研究设计院反应堆燃料及材料重点实验室成都610213 四川大学机械工程学院成都610065

为探究SiC_(f)/SiC复合陶瓷与SiC陶瓷钎焊工艺性的差别,采用Ni基合金钎料在真空1400℃下保温10 min实现了SiC_(f)/SiC复合陶瓷与SiC陶瓷材料的真空钎焊连接,并针对焊后接头焊缝微观形貌特征对Ni基钎料进行成分优化,最终获得焊缝质量良好... 详细信息

为探究SiC_(f)/SiC复合陶瓷与SiC陶瓷钎焊工艺性的差别,采用Ni基合金钎料在真空1400℃下保温10 min实现了SiC_(f)/SiC复合陶瓷与SiC陶瓷材料的真空钎焊连接,并针对焊后接头焊缝微观形貌特征对Ni基钎料进行成分优化,最终获得焊缝质量良好、SiC纤维损伤较小的SiC_(f)/SiC复合陶瓷真空钎焊连接接头。结果显示,SiC陶瓷和SiC_(f)/SiC复合陶瓷与钎料的反应机理相同,生成的反应产物没有差异。由于SiC_(f)/SiC复合陶瓷的结构特点,钎焊过程中钎料会在毛细作用下沿缝隙流失,并与SiC纤维发生反应造成纤维损伤。因此需降低钎料与SiC_(f)/SiC复合陶瓷的反应倾向,避免SiC纤维质量受损。所获结果可为针对SiC_(f)/SiC复合陶瓷连接的钎料成分及钎焊工艺设计提供试验参考。

关键词： SiC_(f)/SiC复合陶瓷 SiC纤维真空钎焊钎料合金成分优化反应驱动力

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