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| 1 | Optimizing mechanical and magnetic properties of AlCoCrFeNi high-entropy alloy via FCC to BCC phase transformation显示文摘FCC,BCC and B2 phases,the most common phases in high-entropy alloys(HEAs),are widely investigated to tailor their mechanical and magnetic performances.The detailed investigation of FCC to BCC/B2 phase transformation of Al Co Cr Fe Ni HEA in this paper reveals its evolution and structure-properties relations in terms of both temperature and holding duration.With increasing heat treatment temperature and duration,such transition will progress simultaneously at both the dendric core(DC)region and interdendric(ID)region and the volume of phase transformation from FCC to BCC phases is greater than FCC to B2 phases,resulting in increased yield strength and saturation magnetization.The obvious phase transition of the Al Co Cr Fe Ni HEA at 1200℃can enhance its yield strength and saturation magnetization as a sacrifice of its fracture strain.However,an excellent combination of mechanical-magnetic properties was achieved when heat-treated at 1100℃for 50 h by optimizing both the transformation and the size of B2 phases.Our present study could pave ways to design the HEAs or other alloys with an optimum combination of mechanical and magnetic properties for application-oriented viewpoints. | Chendong Zhao Jinshan Li Yudong Liu Xiao Ma Yujie Jin William Yi Wang Hongchao Kou Jun Wang | 2021 | Journal of Materials Science & Technology2021，，27： | 3 |
| 2 | Tailoring mechanical and magnetic properties of AlCoCrFeNi high-entropy alloy via phase transformation显示文摘Phase constitutions,either changed by alloying or by phase transformation,are the key factors to determine the magnetic and mechanical performances of high-entropy alloys(HEAs).Using the AlCoCrFeNi HEA as a candidate alloy,this paper demonstrates the effect of phase transformation on both the mechanical and magnetic properties in the multi-phase system.With increasing heat treatment temperature,the sigma(σ)and face-centered-cubic(FCC)phases disappeared at 1000℃and 1200℃,respectively.Such volume fraction changes ofσ,FCC and body-centered-cubic(BCC)phases have divergent effects on mechanical and magnetic properties.The excellent strength-ductility combination will be achieved as the disappearance ofσphase and formation of FCC phase.As for the magnetic properties,the volume fraction of BCC phase plays a major role in determining its saturation magnetization.When the volume fraction change of BCC phase is not evident,the higher volume fraction of FCC phase will influence its magnetization at 2 T.Our present work might provide insights into analyzing the evolution of both mechanical and magnetic properties of HEAs caused by complex phase transformation. | Chendong Zhao Jinshan Li Yudong Liu William Yi Wang Hongchao Kou Eric Beaugnon Jun Wang | 2021 | Journal of Materials Science & Technology2021，，14： | 2 |
| 3 | Diurnal variations of carbon dioxide,methane,and nitrous oxide fluxes from invasive Spartina alterniflora dominated coastal wetland in northern Jiangsu Province显示文摘The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function.Yet,limited attention has been given to their potential influence on greenhouse gas(GHG) emissions,including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget.In this study,we examined the diurnal variation in fluxes of carbon dioxide(CO_2),methane(CH_4),and nitrous oxide(N2O) from a S.alterniflora intertidal flat in June,October,and December of 2013 and April of 2014 representing the summer,autumn,winter,and spring seasons,respectively.We found that the average CH_4 fluxes on the diurnal scale were positive during the growing season while negative otherwise.The tidal flat of S.alterniflora acted as a source of CH_4 in summer(June) and a combination of source and sink in other seasons.We observed higher diurnal variations in the CO_2 and N_2O fluxes during the growing season(1 536.5 mg CO_2 m^(–2) h^(–1) and 25.6 μg N_2O m^(–2) h^(–1)) compared with those measured in the non-growing season(379.1 mg CO_2 m^(–2) h^(–1) and 16.5 μg N_2O m^(–2) h^(–1)).The mean fluxes of CH_4 were higher at night than that in the daytime during all the seasons but October.The diurnal variation in the fluxes of CO_2 in June and N_2O in December fluctuated more than that in October and April.However,two peak curves in October and April were observed for the diurnal changes in CO_2 and N_2O fluxes(prominent peaks were found in the morning of October and in the afternoon of April,respectively).The highest diurnal variation in the N_2O fluxes took place at 15:00(86.4 μg N_2O m^(–2) h^(–1)) in June with an unimodal distribution.Water logging in October increased the emission of CO_2(especially at nighttime),yet decreased N_2O and CH_4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases.The seasonal and diurnal variations of CH_4 and CO_2 fluxes did not correlate to the air and soil temperatures,whereas the seasonal and diurnal variation of the fluxes of N_2O in June exhibited a significant correlation with air temperature.When N_2O and CH_4 fluxes were converted to CO_2-e equivalents,the emissions of N_2O had a remarkable potential to impact the global warming.The mean daily flux(MF) and total daily flux(TDF) were higher in the growing season,nevertheless,the MF and TDF of CO_2 were higher in October and those of CH_4 and N_2O were higher in June.In spite of the difference in the optimal sampling times throughout the observation period,our results obtained have implications for sampling and scaling strategies in estimating the GHG fluxes in coastal saline wetlands. | XU Xinwanghao FU Guanghe ZOU Xinqing GE Chendong ZHAO Yifei | 2017 | Acta Oceanologica Sinica2017，36，4： | 2 |
| 4 | Recent changing patterns of the Changjiang(Yangtze River) Estuary caused by human activities显示文摘To evaluate the controlling factors for coastline change of the Changjiang(Yangtze River) Estuary since 1974,we extracted the mean high tide line from multi-temporal remote sensing images that span from 1974 to 2014 at 2-year intervals.We chose 42 scenes to constrain the changing pattern of the Changjiang Estuary coastline,and implemented GIS technology to analyze the area change of the Changjiang(Yangtze) Subaerial Delta.Runoff,sediment discharge and coastal engineering were withal considered in the analysis of the coastline changes.The coastline has transgressed seaward since 1974,and a part of it presents inter-annual variations.The area of the Changjiang Subaerial Delta increased by 871 km2,with a net accretion rate of 21.8 km2/a.Based on the change of sediment discharge due to the major projects in the Changjiang River Basin,we divided the changing pattern of the coastline into three stages:the slow accretion stage(1974–1986),the moderate accretion stage(1987–2002),and the rapid accretion stage(2003–2014).Liner regression analysis illustrated that there is a significantly positive correlation between the area changes and sediment discharge in the Chongming Eastern Shoal and Jiuduansha.This suggested that sediment load has a fundamental effect on the evolution of the Changjiang Estuary.Construction of Deep Waterway in the North Passage of the Changjiang River(1998–2010) led to a rapid accretion in the Hengsha Eastern Shoal and Jiuduansha by influencing the hydrodynamics in North Passage.Coastal engineering such as reclamation and harbor construction can also change the morphology of the Changjiang Estuary.We defined a contribution rate of area change to assess the impact of reclamation on the evolution of Changjiang Estuary.It turned out that more than 45.3% of area increment of the Changjiang Estuary was attributed to reclamation. | WANG Chenglong ZHAO Yifei ZOU Xinqing XU Xinwanghao GE Chendong | 2017 | Acta Oceanologica Sinica2017，36，4： | 0 |
| 5 | Numerical Investigation on Fracture Initiation Properties of Interface Crack in Dissimilar Steel Welded Joints显示文摘Fracture toughness property is of significant importance when evaluating structural safety.The current research of fracture toughness mainly focused on crack in homogeneous material and experimental results.When the crack is located in a welded joint with high-gradient microstructure and mechanical property distribution,it becomes difficult to evaluate the fracture toughness behavior since the stress distribution may be affected by various factors.In recent years,numerical method has become an ideal approach to reveal the essence and mechanism of fracture toughness behavior.This study focuses on the crack initiation behavior and driving force at different interfaces in dissimilar steel welded joints.The stress and strain fields around the crack tip lying at the interfaces of ductile-ductile,ductile-brittle and brittle-brittle materials are analyzed by the numerical simulation.For the interface of ductile-ductile materials,the strain concentration on the softer material side is responsible for ductile fracture initiation.For the ductile-brittle interface,the shielding effect of the ductile material plays an important role in decreasing the fracture driving force on the brittle material side.In the case of brittle-brittle interface,a careful matching is required,because the strength mismatch decreases the fracture driving force in one side,whereas the driving force in another side is increased.The results are deemed to offer support for the safety assessment of welded structures. | Longfei Zhao Chendong Shao Yasuhito Takashima Fumiyoshi Minami Fenggui Lu | 2020 | Chinese Journal of Mechanical Engineering2020，33，3： | 0 |
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