Lamellar globularization in the dual-phase titanium alloy is the key to improving plasticity and strength.However,the mechanism has not been fully elucidated so far.In this work,the role of phase/grain bound-ary in th...Lamellar globularization in the dual-phase titanium alloy is the key to improving plasticity and strength.However,the mechanism has not been fully elucidated so far.In this work,the role of phase/grain bound-ary in the static globularization of TC17 alloy was systematically studied by setting differentαphase con-tent before annealing through low-and high-temperature deformation.Isothermal compression causes the parallel distribution and fragmentation of 3Dαplates and few globularαparticles are formed at a strain rate of 1 s^(-1).Post-deformation annealing promotes the static globularization ofαphase while it is affected by initialαphase content.After 730°C deformation,the development ofα/αinterface by absorbing dislocations promotes the formation of globularαgrains based on the nucleation of sepa-ratedαparticles and pre-recoveryαsubgrain during subsequent annealing.Theα/α/βandα/β/βtriple junctions formed due to highαcontent with about 36%volume fraction are favorable for the further nucleation and growth of globularαgrains by reducing interface energy,forming a 3D irregularαplate.Then nucleation and growth of theβphase dominate the microstructure evolution during subsequent an-nealing,resulting in the local dissolution of the plate and formation ofαrods.After 850°C deformation,theαphase tends to nucleate at theβ/β/βtriple junctions and grow into a lamellar shape along the high energyβ/βgrain boundary due to lowαcontent with about 7%volume fraction.Theαnucleation that maintains the Burgers orientation relationship(BOR)with the surroundingβphase grows along the habit plane and thickens slowly,resulting in the formation of a precipitatedαplate with a flat surface and the suppression of static globularization.The comprehensive investigation of lamellar globularization provides guidance for optimizing the 3D microstructure and properties of dual-phase titanium alloy.展开更多
From 26 November to 1 December 2022,intense cold air masses swept across China from northwest to south,resulting in a nationwide cold air outbreak(CAO)case characterised by drastic and sudden temperature drops with ra...From 26 November to 1 December 2022,intense cold air masses swept across China from northwest to south,resulting in a nationwide cold air outbreak(CAO)case characterised by drastic and sudden temperature drops with rain,snow and strong winds.The physical processes that dominate the intensification of the cold air masses during this CAO event remain unclear.In this study,the evolution of the CAO case,which is indicated by the dry static energy(DSE),is investigated using a novel approach in the framework of Lagrangian backtracking.The dominant processes can be identified by decomposing the DSE change into four diabatic heating terms due to shortwave radiation,longwave radiation,latent heat and turbulent processes.Overall,in this case,most of the cold air parcels originated from the east of Novaya Zemlya and crossed Central Siberia before reaching China.Thus,these air parcels mainly manifested on the northwest‒southeast path.The duration of the cold air intensification differed between subregions.The cold air parcels experienced long cooling periods(approximately 9 d)before reaching northern China(i.e.Northwest,North and Northeast China),whilst the southern parts(i.e.Central,East and South China)underwent relatively short cooling periods(6-8 d).Accordingly,the cold air affecting northern China is more intense than that affecting the southern parts,especially for East and South China.For all six subregions,longwave radiative cooling is identified as the dominant contributor to the cold air intensification,and the latent heat processes as the secondary contributor.The weakening of cold air parcels as they approach and pass over these regions is driven by turbulent processes and shortwave heating.Central Siberia and Lake Baikal are identified as key areas for the intensification of cold air passing over both regions.In addition,air parcels affecting Northwest China are intensely cooled as they pass over the Junggar Basin,while the North China Plain is a key area for cooling air parcels reaching Central,East and South展开更多
基金the financial support from the National Key R&D Program of China(Grant No.2022YFB3707201)the Science Fund for Distinguished Young Scholars from Shaanxi Province(No.2020JC-17)+2 种基金NPU AoXiang Distinguished Young Schol-ars(Grant Nos.0604022GH0202143,0604022SH0201143)the Funding of Young Top-notch Talent of the National Ten Thousand Talent Program,the Fundamental Research Funds for the Central Universities(No.3102022gxb004)Science Center for Gas Tur-bine Project(No.P2022-A-IV-001-002)。
文摘Lamellar globularization in the dual-phase titanium alloy is the key to improving plasticity and strength.However,the mechanism has not been fully elucidated so far.In this work,the role of phase/grain bound-ary in the static globularization of TC17 alloy was systematically studied by setting differentαphase con-tent before annealing through low-and high-temperature deformation.Isothermal compression causes the parallel distribution and fragmentation of 3Dαplates and few globularαparticles are formed at a strain rate of 1 s^(-1).Post-deformation annealing promotes the static globularization ofαphase while it is affected by initialαphase content.After 730°C deformation,the development ofα/αinterface by absorbing dislocations promotes the formation of globularαgrains based on the nucleation of sepa-ratedαparticles and pre-recoveryαsubgrain during subsequent annealing.Theα/α/βandα/β/βtriple junctions formed due to highαcontent with about 36%volume fraction are favorable for the further nucleation and growth of globularαgrains by reducing interface energy,forming a 3D irregularαplate.Then nucleation and growth of theβphase dominate the microstructure evolution during subsequent an-nealing,resulting in the local dissolution of the plate and formation ofαrods.After 850°C deformation,theαphase tends to nucleate at theβ/β/βtriple junctions and grow into a lamellar shape along the high energyβ/βgrain boundary due to lowαcontent with about 7%volume fraction.Theαnucleation that maintains the Burgers orientation relationship(BOR)with the surroundingβphase grows along the habit plane and thickens slowly,resulting in the formation of a precipitatedαplate with a flat surface and the suppression of static globularization.The comprehensive investigation of lamellar globularization provides guidance for optimizing the 3D microstructure and properties of dual-phase titanium alloy.
基金supported by the National Nature Science Foundation of China(41875119 and 42005118)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(2642023095)+1 种基金Science and Technology Development Plan in Jilin Province of China(20230203135SF)Open Research of State Key Laboratory of Severe Weather(2022LASW-B05).
文摘From 26 November to 1 December 2022,intense cold air masses swept across China from northwest to south,resulting in a nationwide cold air outbreak(CAO)case characterised by drastic and sudden temperature drops with rain,snow and strong winds.The physical processes that dominate the intensification of the cold air masses during this CAO event remain unclear.In this study,the evolution of the CAO case,which is indicated by the dry static energy(DSE),is investigated using a novel approach in the framework of Lagrangian backtracking.The dominant processes can be identified by decomposing the DSE change into four diabatic heating terms due to shortwave radiation,longwave radiation,latent heat and turbulent processes.Overall,in this case,most of the cold air parcels originated from the east of Novaya Zemlya and crossed Central Siberia before reaching China.Thus,these air parcels mainly manifested on the northwest‒southeast path.The duration of the cold air intensification differed between subregions.The cold air parcels experienced long cooling periods(approximately 9 d)before reaching northern China(i.e.Northwest,North and Northeast China),whilst the southern parts(i.e.Central,East and South China)underwent relatively short cooling periods(6-8 d).Accordingly,the cold air affecting northern China is more intense than that affecting the southern parts,especially for East and South China.For all six subregions,longwave radiative cooling is identified as the dominant contributor to the cold air intensification,and the latent heat processes as the secondary contributor.The weakening of cold air parcels as they approach and pass over these regions is driven by turbulent processes and shortwave heating.Central Siberia and Lake Baikal are identified as key areas for the intensification of cold air passing over both regions.In addition,air parcels affecting Northwest China are intensely cooled as they pass over the Junggar Basin,while the North China Plain is a key area for cooling air parcels reaching Central,East and South
