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Journal of Magnesium and Alloys 2023年第9期11卷 3200-3213页

作者： T.Nakata c.xu L.Geng S.Kamado Nagaoka University of Technology 1603-1KamitomiokaNagaoka 940-2188Japan School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001China

The origin of unique parallel alignment of(0001) poles to transverse direction(TD) was investigated using Mg-3Al-0.4Mn(mass%)alloy sheets rolled with different process conditions. When rolling was performed with intermediate reheating, the alloy showed a sluggish static recrystallization(SRX) behavior during post-annealing, facilitating the nucleation and growth of statically recrystallized grains from extension twins. This resulted in the apparent texture component with the parallel alignment of the(0001) poles to the TD, and the sheet exhibited good ductility for both the rolling direction(RD) and TD. In contrast, continuous rolling without intermediate reheating led to the formation of severely deformed regions near double twins. SRX was promoted at such regions, forming a typical basal textural feature with weak RD-split of the(0001) poles. Although extension twins were formed after the continuous rolling, SRX was facilitated at the severely deformed regions with double twins, and the formation of the unique alignment of the(0001) poles to the TD was suppressed. The RD-split texture led to the large elongation to failure along the RD, while it along the TD decreased owing to the narrow distribution of the(0001)poles toward the TD, resulting in the in-plane anisotropy in ductility.

关键词： Magnesium Rolling Twinning Static recrystallization Texture

On the microstructural origin of premature failure of creep strength enhanced martensitic steels

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Journal of Materials Science & Technology 2021年第28期87卷 269-279页

作者： J.Li c.xu G.Zheng W.J.Dai c.c.Bu G.chen MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology Engineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing210094China Nanjing Jiuzhu New Materials Institute co. Ltd.Nanjing211151China condensed Materials Laboratory co. Ltd.Yangzhou225200China Yangzhou chengde Steel Pipe co. Ltd.Yangzhou225200China

The creep strength enhanced martensitic steels are key material for the main power generating units in ultra-supercritical *** on the evaluation of their creep rupture life show there is an overestimation of rupture life after long-term creep,which is known as premature ***,the microstructural origin of the premature failure remains *** in this study,we have carefully investigated the microstructural transformations and their influences on creep rupture behavior,showing that the evolution of martensite and M_(23)c_(6) carbides as well as Laves phase are responsible for the premature *** using multi-step TTP-LMP method,we confirmed a three-stage creep rupture behavior under different stress *** quantitative analysis showed that the coarsening of M_(23)c_(6) carbides and recovery of martensite exert equal and dominant effects on the premature failure in the medium stress region,while precipitation and coarsening of Laves phase are responsible for the premature failure in the low stress region.

关键词： creep strength enhanced martensitic steel Premature failure M_(23)c_(6)carbides Martensite recovery Laves phase

Improvement of strength and ductility synergy in a room-temperature stretch-formable Mg-Al-Mn alloy sheet by twin-roll casting and low-temperature annealing

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Journal of Magnesium and Alloys 2022年第4期10卷 1066-1074页

作者： T.Nakata c.xu K.Kaibe Y.Yoshida K.Yoshida S.Kamado Nagaoka University of Technology 1603-1KamitomiokaNagaoka 940-2188Japan School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001China Sumitomo Electric Industries Ltd.1-1-1 KoyakitaItami 664-0016Japan

Strength and ductility synergy in an Mg-3mass%Al-Mn(AM30)alloy sheet was successfully improved via twin-roll casting and annealing at *** AM30 alloy sheet produced by twin-roll casting,homogenization,hot-rolling,and subsequent annealing at 170℃ for 64 h exhibits a good 0.2%proof stress of 170 MPa and a large elongation to failure of 33.1%along the rolling *** sheet also shows in-plane isotropic tensile properties,and the 0.2%proof stress and elongation to failure along the transverse direction are 176 MPa and 35.5%,*** the sheet produced by direct-chill casting also shows moderate strengths if the annealing condition is same,the direct-chill casting leads to the deteriorated elongation to failure of 23.9%and 30.0%for the rolling and transverse directions,*** well as such excellent tensile properties,a high room-temperature stretch formability with an Index Erichsen value of 8.3 mm could be obtained in the twin-roll cast sheet annealed at 170℃ for 64 *** annealing at a higher temperature further improves the stretch formability;however,this results in the decrease of the tensile *** characterization reveals that the excellent combination of strengths,ductility,and stretch formability in the twin-roll cast sheet annealed at the low-temperature annealing is mainly attributed to the uniform recrystallized microstructure,fine grain size,and circular distribution of(0001)poles away from the normal direction of the sheet.

关键词： Magnesium Rolling Tensile property Room temperature formability Twinning

Experimental study of corner separation and unsteady characteristics in linear compressor cascades with and without sweeping jet actuator

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Propulsion and Power Research 2024年第3期13卷 360-374页

作者： S.W.chen W.H.Li c.xu Q.H.Meng School of Energy Science and Engineering Harbin Institute of TechnologyHarbinHeilongjiang 150001China AVIc Shenyang Aircraft Design and Research Institute Shenyang 110035China

Sweeping jet actuator(SJA)has been widely applied for activeflow control in *** this paper,the SJA character in compressor cascade and its performance for separation control in innerflows are ***-averaged and transientflowfield measurement,together with visualization methods are *** is found that endwall effects are important for both SJA behaviors and SJA performance for separation control in compressor *** is a maximum of 12.7%total pressure loss reduction with SJA placed near the separation position,close to the endwall and under *** characteristic frequencies in theflowfield contribute to the capture of influence regions of vortices and excitation *** concentrated shedding vortices and SJA jets impact region helped to judge that SJA energizes low momentumfluids in a large region and matches the high loss core *** be concrete,theflow separation control mechanism of SJA lies on the interruption of the blade suction surface boundary layer development and the restriction of the lifting of the boundary layer from end-wall towards blade suction surface.

关键词： compressor cascade Activeflow control Sweeping jet actuator corner separation Oilflow visualization

Enhancing strength and creep resistance of Mg-Gd-Y-Zn-Zr alloy by substituting Mn for Zr

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Journal of Magnesium and Alloys 2019年第3期7卷 388-399页

作者： c.xu T.Nakata G.H.Fan X.W.Li G.Z.Tang S.Kamado School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001PR China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan School of Material Science and Engineering Harbin University of Science and TechnologyHarbin 150040PR China

The age-hardening behavior and mechanical properties of the extruded Mg-2Gd-1.2Y-0.5Zn(at.%)alloy with Zr or Mn additions were *** results show that Mn added alloy exhibits more remarkable age-hardening response than Zr added alloy,which is attributed to the fact that partitioning of Mn into the β'phases,β'precipitates and long period stacking ordered(LPSO)phases leads to the decrement in(G d+Y)concentrations in the second phases,facilitating the precipitation during aging *** peak-aged alloys show bimodal microstructure comprising the fine DRXed grains with nano-sized β phases pinned at DRXed grain boundaries as well as coarse worked grains with strong fiber *** strength and good thermal stability were obtained in both peak-aged Mn and Zr added *** the peak-aged Mn added alloy shows higher strength and superior creep resistance due to its denser β'precipitates,thin LPSO phases and γ'precipitates and higher area fraction of worked grains with strong fiber *** 0.2% tensile proof stress and ultimate tensile strength of peak-aged Mn added alloy reach up to 454 MPa and 508 MPa,respectively,with elongation of 3.2%at room *** minimum creep rate of the peak-aged Mn added alloy at 250℃/150 MPa is 2.4 × 10^-8 s^-1,which is superior than previously reported extruded Mg-Gd based alloys.

关键词： Magnesium alloys Rare earth(RE) Precipitation Mechanical properties creep resistance

Uncovering the hierarchical clusters in the heat-affected zone of an electron beam weldedα/βtitanium alloy joint

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Journal of Materials Science & Technology 2024年第7期174卷 120-132页

作者： c.xu X.H.Shao H.J.Yang M.Lv H.Q.Liu X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Suzhou laboratory Suzhou 215028China Department of Mechanical Engineering Kyushu UniversityFukuoka 819-0395Japan Bay Area center for Electron Microscopy Songshan Lake Materials LaboratoryDongguan 523808China

Using high-resolution transmission Kikuchi diffraction(TKD)and transmission electron microscopy(TEM),we examined the hierarchical clusters that form in situ in the heat-affected zone(HAZ),which are com-monly referred to as“ghost”structures,of bimodal titanium alloy Ti-5Al-2Sn-2Zr-4Mo-4cr(wt%,Tc17).The ghost structures are enriched with Al elements but poor in Mo and cr compared to the surroundingβ*** results show that the ghost structure in middle-HAZ mainly consists ofα_(L)laths with a high-angle grain boundary,which exhibits the classic Burgers orientation relationship(BOR)with the host matrix,while it encircles theα_(P)grains in *** the ghost structure is evidenced to form via in-complete martensitic *** results further confirm that the ghost structure is composed ofαL and tinyβ_(L)laths with BOR,with the former being enriched with Al and poor with cr and Mo,while the latter is the ***,twoα_(L)variant clusters with a check-mark morphology are fre-quently observed viewed along[0001]_(αL)//[110]_(βL)directions,which are dominated by the crystallographic and geometrical relationships betweenαandβ*** on the microstructural characterization,it is hypothesized that the ghost structure is transformed from the initialα_(P)phase,due to the coupling ef-fect of high thermal stress(which induces the formation of a large number of dislocations)and element diffusion caused by sudden temperature increase and plunge cooling in the HAZ during the welding pro-cess.

关键词： Tc17 titanium alloy Electron beam welding(EBW) The ghost structure Transmission Kikuchi diffraction(TKD) Transmission electron microscopy(TEM)

control of dislocation density maximizing precipitation strengthening effect

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Journal of Materials Science & Technology 2022年第32期127卷 133-143页

作者： c.xu W.J.Dai Y.chen Z.X.Qi G.Zheng Y.D.cao J.P.Zhang c.c.Bu G.chen MIIT Key Laboratory of Advanced Metallic and Internetallic Materials Technology Engineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China

The strength-ductility trade-off has been the most challenging problem for structural metals for *** strengthening is an ideal approach to enhance the strength without significantly sacrificing the *** nanoprecipitates have been successfully acquired by nanostructural design,but the number density of nanoprecipitates cannot be further *** attempted to enhance number density by introducing highly potent nucleation sites(e.g.,dislocations).However,there remains controversy over the influence of dislocations on the nucleation and growth of coherent nanoprecipitates with minimized nucleation ***,cu-rich nanoprecipitates in an HSLA steel,as a typical type of coherent nanoprecipitates,are *** combining analytical calculation and experiments,we show that dislocations are harmful for the formation of large numbered cu-rich nanoprecipitates in a certain density *** dislocations deprive solute atoms which decrease homogenous precipitation that cannot be compensated by the increase in heterogeneous *** such circumstance,cu-rich nanoprecipitates have smaller number density but larger size and higher fraction of incoherent structures due to rapid Ostwald *** a result,by controlling dislocation density,the yield strength is increased by 24%without obvious loss in ductility as compared with traditional solution-quench-age *** work would help to optimize composition and processing routes that fully exploit the nanoprecipitation strengthening effect.

关键词： cu-rich nanoprecipitates crystallographic defects Nucleation Structural transformation Ostwald ripening

Quasi-in-situ observing the rare earth texture evolution in an extruded Mg-Zn-Gd alloy with bimodal microstructure

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Journal of Magnesium and Alloys 2021年第5期9卷 1818-1827页

作者： M.G.Jiang c.xu H.Yan T.Nakata Z.W.chen c.S.Lao R.S.chen S.Kamado E.H.Han college of Mechatronics and control Engineering Shenzhen University3688 Nanhai AveShenzhen 518060China The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of Sciences62 Wencui RoadShenyang 110016China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan

The static recrystallization and associated texture evolution were investigated in an extruded Mg-Zn-Gd alloy with bimodal microstructure based on a quasi-in-situ electron back-scatter diffraction(EBSD)*** typical rare earth(RE)texture formed during annealing,evolving from the bimodal microstructure with[1010]basal fiber texture that consisted of fine recrystallized(RXed)grains and coarse unrecrystallized(un RXed)grains elongated along the extrusion *** both RXed and un RXed regions,the RXed nucleation produced randomized orientations without preferred selection and the RXed grains with RE texture orientation had more intensive growth ability than those with basal fiber orientation,thereby leading to the preferred selection of RE texture orientation during grain *** relationships between stored strain energy,solute drag,grain growth and texture evolution are discussed in *** study provided direct evidence of the RE texture evolution in an extruded Mg-RE alloy,which assists in understanding the formation mechanisms for RE texture during extrusion and better developing wrought Mg alloys with improved formability.

关键词： Magnesium alloy Rare earth texture Extrusion Annealing Recrystallization

The development of ^(222)Rn detectors for JUNO prototype

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Radiation Detection Technology and Methods 2018年第1期2卷 32-37页

作者： Y.P.Zhang J.c.Liu c.Guo Y.B.Huang c.xu M.Y.Guan c.G.Yang P.Zhang Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of ScienceBeijingChina School of Physics University of Chinese Academy of ScienceBeijingChina School of Nuclear Science and Technology University of South ChinaHengyangChina

Background JUNO(The Jiangmen Underground Neutrino Observatory)is a multipurpose neutrino experiment,and it has very strict requirements for the *** to the Mc simulation for JUNO experiment requirements,the Rn concentration in the water of the veto detector should be less than 0.2Bq/m^(3).In order to measure such low Rn concentration,two kinds of high-sensitivity Rn measurement systems have been *** Based on the water system of JUNO prototype,two kinds of high-sensitivity Rn detectors have been developed,namely the Si-PIN Rn detector and the LS Rn *** Si-PIN Rn detector uses a Si-PIN photodiode to detect theαfrom ^(214)Po decay and the LS Rn detector detects the coincident signals ofβfrom ^(214)Bi decay andβfrom ^(214)Po *** The background measurement of Si-PIN Rn detector and LS Rn detector is performed to estimate the *** sensitivity of Si-PIN Rn detector is around 9.0mBq/m^(3) and the sensitivity of LS Rn detector is around 64.0Bq/m^(3).conclusion Both of the Si-PIN Rn detector and the LS Rn detector are working well with the JUNO prototype at present,and both of them can be developed as an online Rn concentration monitoring device for JUNO veto detector.

关键词： Radon Si-PIN Liquid scintillator

Engineering protein interfaces yields ferritin disassembly and reassembly under benign experimental conditions

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Engineering protein interfaces yields ferritin disassembly a...