In this study,Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloys samples with the same diameter(8 mm)were prepared by using self-designed molds(viz.refractory steel,pure graphite,and copper molds)with differ...In this study,Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloys samples with the same diameter(8 mm)were prepared by using self-designed molds(viz.refractory steel,pure graphite,and copper molds)with different cooling capacities.Moreover,by eliminating the size effect,the effect of the cooling rate on the microstructure and compression deformation behavior of Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloys was investigated.Differentiation of the cooling curves revealed that the instantaneous cooling rates of the alloy melt at the glass transition temperature(Tg)are 45,52,and 64 K·s^(-1) for refractory steel,pure graphite,and copper molds,respectively.X-ray diffraction,differential scanning calorimetry,and highresolution transmission electron microscopy analysis revealed that with the decrease in the cooling rate,trace icosahedral-like atomic clusters and nanocrystals appear in local areas of the amorphous alloy and that the amount of free volume decreases with the increase in the amount of icosahedra-like atomic clusters and nanocrystals.Compression test results revealed that the elastic strain,yield strength,and compressive strength of the amorphous alloy marginally change with the decrease in the cooling rate,while the plastic strain gradually increases.By fitting,the effective size of the vein-like pattern was linearly related to the enthalpy released during structural relaxation and plastic strain,indicating that at a low cooling rate,the trace nanocrystals in the amorphous alloy could not effectively improve its plasticity and that the amount of free volume mainly affects its plasticity.展开更多
In this study, SiC/AA6061 composites with different SiC volume fractions （5%, 10%, 15% and 20%） were fabricated by spark plasma sintering. The deformation behaviour of the composites was studied by uni- axial compre...In this study, SiC/AA6061 composites with different SiC volume fractions （5%, 10%, 15% and 20%） were fabricated by spark plasma sintering. The deformation behaviour of the composites was studied by uni- axial compression test at temperatures from 573 K to 773 K and strain rates between 0.001 s^-1 and 1 s^-1. Results indicate that the flow stress of SiCIAA6061 composites increases with the increase of SiC volume fraction, with the decrease of deformation temperature and with the decrease of strain rate. The main deformation mechanism of the composites is dynamic recrystallisation （DRX）, and the DRX degree depends on the processing parameters of deformation. Higher SiC volume fraction, higher deformation temper- ature and lower deformation strain rate promote the occurrence of DRX. The strain rate sensitivity and deformation activation energy of SiC/AA6061 composites are calculated. Results show that with the in- crease in deformation temperature and the decrease in SiC volume fraction, the strain rate sensitivity of the composites increases. From 573 K to 773 K, the average deformation activation energy of 5vol.%SiC/ AA6061, 10voI.%SiC/AA6061, 15voI.%SiC/AA6061 and 20vol.%SiC/AA6061 are 20Z91, 230.88, 237.7 and 249.87 kJ mol^-1, respectively. The optimum hot working zone of the SiC/AA6061 composites is in the tem- perature range of 723 K to 773 K at strain rates from 0.1 s^-1 to 1 s^-1.展开更多
Excellent comprehensive mechanical properties and corrosion resistance of TiZrNb equiatomic ratio medium-entropy alloy were obtained through recrystallization and spinodal decomposition.In addition to solid solution s...Excellent comprehensive mechanical properties and corrosion resistance of TiZrNb equiatomic ratio medium-entropy alloy were obtained through recrystallization and spinodal decomposition.In addition to solid solution strengthening and recrystallization,the excellent mechanical properties can also be attributed to the hindering effect of nanoprecipitation formed via spinodal decomposition on the movement of dislocations.The high atomic arrangement density due to spinodal decomposition reduces the surface energy of the alloy passivation film,thereby increasing the activation energy of dissolution and the bonding energy between atoms,which improve the corrosion resistance and stability of the alloy passivation film.This work provides a new strategy to control the mechanical properties and corrosion resistance by combining recrystallization and spinodal decomposition.展开更多
In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstr...In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstructural characterization of the as-cast alloys is carried out by X-ray diffraction,optical microscopy and transmission electron microscopy.The results reveal that Nb-containing Ti-Zr alloys transformed from single a phase→α+α"+β phase single β phase double β phases with increasing Nb content.In the case of β-type alloys,the addition of Nb improves the bonding energy between atoms,reduces the grain size,increases the elastic modulus,improves the yield strength and renders superior work-hardening behavior.Moreover,the current study provides mechanistic insights into microstructural evolution and strengthening of Nb-containing Ti-Zr alloys with increasing Nb content.Herein,the addition of 5 at.% Nb resulted in an abnormal work hardening during compression deformation under the synergistic influence of stress-induced martensite transformation of β phase and stress-induced twinning of α phase.Moreover,the biomechanical properties are evaluated to demonstrate the potential of Nb-containing Ti-Zr alloys in biological applications.展开更多
An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents ...An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents and the microstructure of the composites and the particle size of the reinforcement were analysed using X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results have shown that TiCp/Al composite with 40～70 vol. pct TiC particle reinforcement and high relative density can be directly obtained by TE/QP. TiC is the only reaction product when Al content in Al-Ti-C system is no more than 60 vol. pct, but Al3Ti phase will also form when Al content is more than 60 vol. pct. Increasing Al content prolongs the initial reaction time, reduces the highest reaction temperature and the reaction rate, and decreases the size of TiC particles. In addition, the microstructure of TiCp/Al composite and the structure of interface between TiCp and Al are studied using SEM and transmission electron microscopy （TEM）. The results show that the in-situ synthesized TiC particle has fcc cubic structure. The orientation between TiC particles and Al matrix can be described as （220）Al//（022）TiC and [112]Al//[011]TiC. Results of the mechanical property tests reveal that the ultimate strength （σ） and modulus （E） are 687 MPa and 142 GPa respectively when the Al content is 40 vol. pct. On contrary, 6 elongation increases by 3.2% with increasing Al content.展开更多
Impurity segregation even small amounts,can drastically change the cohesive properties of the grain boundaries(GB),eventually leading to intergranular embrittlement and failure of the materials,thereby effectively con...Impurity segregation even small amounts,can drastically change the cohesive properties of the grain boundaries(GB),eventually leading to intergranular embrittlement and failure of the materials,thereby effectively controlling the types and the concentrations of the impurity is very important.In this work,the nonmetallic impurities(C,H,O,N) segregation and their effects on the strength of Zr(10 1 2) GB were thoroughly investigated using first-principles calculations based on density functional theory.A comprehensive analysis of the interstitial configurations and the relative site energies indicating that C,N and O overwhelmingly prefer the octahedral sites,only H,prefers to reside in the tetrahedral sites.Moreover,the strengthening/embrittlement potency of impurity atoms on the GB was estimated using both the Rice-Wang model and first-principles tensile test calculations.The results show that all impurities,exhibit a strong segregation tendency near the GB region.The segregation of C,N and O has a remarkable strengthening effect on strength of the GB,whereas the presence of impurity H weaken the GB.Most importantly,the underlying mechanism of the strength change of the GBs due to the segregation of impurities was profoundly discussed by charge density and the bond lengths analyses,revealing that the strengthening effect especially for C-doped GB,mainly comes from an enhancement of the charge density across the GB plane.In the end,we expect that our results will be certainly useful for future theoretical and experimental investigations on Zr and its alloys.展开更多
Ciliated protists(ciliates)represent a morphologically and genetically diverse group of single-celled eukaryotes,the phylogeny of which is critical for understanding eukaryotic evolution.Through international collabor...Ciliated protists(ciliates)represent a morphologically and genetically diverse group of single-celled eukaryotes,the phylogeny of which is critical for understanding eukaryotic evolution.Through international collaborations,the Laboratory of Protozoology at Ocean University of China(OUC-group)has conducted detailed research on ciliate phylogeny based on expanded taxonomic sampling,employing single gene as well as multi-gene markers,and phylogenomic datasets.We have systematically investigated>1000 ciliate species spanning~40 orders,sampled from diverse biotopes including marine environments in China seas and freshwater wetlands.This comprehensive sampling has generated three key datasets:(1)genomic DNA extracts from~2600 strains,(2)~2300 sequences of marker genes,and(3)single-cell genomic and/or transcriptomic datasets from~120 species.Based on these datasets,the phylogenetic relationships covering all classes and most orders have been thoroughly reconstructed and investigated,resulting in the establishment of 93 new supraspecies taxa comprising two classes(Mesodiniea and Protocruziea),two subclasses(Protohypotrichia and Synhymenia),two orders(Wilbertomorphida and Lynnellida),11 families,and 76 genera.Moreover,we have reconstructed a genome-scale tree of life for ciliates and provided an updated classification of the phylum Ciliophora.Furthermore,based on the robust phylogenetic tree of ciliates,we provide more reliable estimates for the origins and divergence times of the main ciliate groups.Future studies integrating advanced genomics,innovations in culturing and interdisciplinary applications will refine the ciliate tree of life,with broader impacts for our understanding of eukaryotic evolution and biodiversity.展开更多
Psammophillic ciliates are an integral part of the foodweb despite being underrepresented in terms of molecular phylogeny and modern taxonomy.To investigate the karyorelictean group,sampling was conducted in interstit...Psammophillic ciliates are an integral part of the foodweb despite being underrepresented in terms of molecular phylogeny and modern taxonomy.To investigate the karyorelictean group,sampling was conducted in interstitial marine habitats in China for ciliates living between the sand grains,resulting in an examination of the families Cryptopharyngidae Jankowski,1980 and Kentrophoridae Jankowski,1980.Three species,i.e.,Cryptopharynx setigerus Kahl,1928,Kentrophoros fasciolatus(Sauerbrey,1928)Foissner,1995 and K.fistulosus(Fauré-Fremiet,1950)Foissner,1995,are clearly recognized as being cosmopolitan,while other species await further recording.Phylogenetic analyses were carried out based on updated data.These revealed that the families Cryptopharyngidae and Kentrophoridae are closely related,and most genera studied are monophyletic,although Cryptopharynx qingdaoensis n.sp.is located within the Kentrophoridae branch.Brief revisions of two genera,namely Cryptopharynx Kahl,1928 and Kentrophoros Sauerbrey,1928,are provided including keys to the iden-tification of nine species belonging to the former and 12 species belonging to the latter.One new genus,Parakentrophoros n.gen.,and one new species,Cryptopharynx qingdaoensis n.sp.,are described and a new combination,Parakentrophoros canalis(Wright,1982)n.comb.,is established.Finally,it appears that the subapical oral apparatus undergoes a gradual degeneration process from Cryptopharyngidae to Kentrophoridae.展开更多
基金supported by the National Natural Science Foundation of China(Grant no.52071278/51827801)the National Key Research and Development Program of China(Grant no.2018YFA0703603)。
文摘In this study,Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloys samples with the same diameter(8 mm)were prepared by using self-designed molds(viz.refractory steel,pure graphite,and copper molds)with different cooling capacities.Moreover,by eliminating the size effect,the effect of the cooling rate on the microstructure and compression deformation behavior of Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5) amorphous alloys was investigated.Differentiation of the cooling curves revealed that the instantaneous cooling rates of the alloy melt at the glass transition temperature(Tg)are 45,52,and 64 K·s^(-1) for refractory steel,pure graphite,and copper molds,respectively.X-ray diffraction,differential scanning calorimetry,and highresolution transmission electron microscopy analysis revealed that with the decrease in the cooling rate,trace icosahedral-like atomic clusters and nanocrystals appear in local areas of the amorphous alloy and that the amount of free volume decreases with the increase in the amount of icosahedra-like atomic clusters and nanocrystals.Compression test results revealed that the elastic strain,yield strength,and compressive strength of the amorphous alloy marginally change with the decrease in the cooling rate,while the plastic strain gradually increases.By fitting,the effective size of the vein-like pattern was linearly related to the enthalpy released during structural relaxation and plastic strain,indicating that at a low cooling rate,the trace nanocrystals in the amorphous alloy could not effectively improve its plasticity and that the amount of free volume mainly affects its plasticity.
基金funded by the National Basic Research Program of China (No. 2013CB733000)the Guangxi Natural Science Foundation (No. 2015GXNSFBA139238)
文摘In this study, SiC/AA6061 composites with different SiC volume fractions （5%, 10%, 15% and 20%） were fabricated by spark plasma sintering. The deformation behaviour of the composites was studied by uni- axial compression test at temperatures from 573 K to 773 K and strain rates between 0.001 s^-1 and 1 s^-1. Results indicate that the flow stress of SiCIAA6061 composites increases with the increase of SiC volume fraction, with the decrease of deformation temperature and with the decrease of strain rate. The main deformation mechanism of the composites is dynamic recrystallisation （DRX）, and the DRX degree depends on the processing parameters of deformation. Higher SiC volume fraction, higher deformation temper- ature and lower deformation strain rate promote the occurrence of DRX. The strain rate sensitivity and deformation activation energy of SiC/AA6061 composites are calculated. Results show that with the in- crease in deformation temperature and the decrease in SiC volume fraction, the strain rate sensitivity of the composites increases. From 573 K to 773 K, the average deformation activation energy of 5vol.%SiC/ AA6061, 10voI.%SiC/AA6061, 15voI.%SiC/AA6061 and 20vol.%SiC/AA6061 are 20Z91, 230.88, 237.7 and 249.87 kJ mol^-1, respectively. The optimum hot working zone of the SiC/AA6061 composites is in the tem- perature range of 723 K to 773 K at strain rates from 0.1 s^-1 to 1 s^-1.
基金financially supported by the National Key R&D Program of China(No.2018YFA0703602)the Hebei Provincial Department of Education Funding Project for Cultivating Innovative Ability of Graduate Students(No.CXZZBS2021130)the Beijing Postdoctoral Research Foundation(No.2021-ZZ-075)。
文摘Excellent comprehensive mechanical properties and corrosion resistance of TiZrNb equiatomic ratio medium-entropy alloy were obtained through recrystallization and spinodal decomposition.In addition to solid solution strengthening and recrystallization,the excellent mechanical properties can also be attributed to the hindering effect of nanoprecipitation formed via spinodal decomposition on the movement of dislocations.The high atomic arrangement density due to spinodal decomposition reduces the surface energy of the alloy passivation film,thereby increasing the activation energy of dissolution and the bonding energy between atoms,which improve the corrosion resistance and stability of the alloy passivation film.This work provides a new strategy to control the mechanical properties and corrosion resistance by combining recrystallization and spinodal decomposition.
基金the National Natural Science Foundation of China(Grant no.51531005/51827801/51671166)。
文摘In order to expand the application horizon of Ti-Zr based alloys,the influence of Nb content on phase composition,microstructural evolution and biomechanical properties is systematically studied.The phase and microstructural characterization of the as-cast alloys is carried out by X-ray diffraction,optical microscopy and transmission electron microscopy.The results reveal that Nb-containing Ti-Zr alloys transformed from single a phase→α+α"+β phase single β phase double β phases with increasing Nb content.In the case of β-type alloys,the addition of Nb improves the bonding energy between atoms,reduces the grain size,increases the elastic modulus,improves the yield strength and renders superior work-hardening behavior.Moreover,the current study provides mechanistic insights into microstructural evolution and strengthening of Nb-containing Ti-Zr alloys with increasing Nb content.Herein,the addition of 5 at.% Nb resulted in an abnormal work hardening during compression deformation under the synergistic influence of stress-induced martensite transformation of β phase and stress-induced twinning of α phase.Moreover,the biomechanical properties are evaluated to demonstrate the potential of Nb-containing Ti-Zr alloys in biological applications.
文摘An in-situ TiCp/Al composite was prepared by a thermal explosion/quick pressure method （TE/QP）. The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents and the microstructure of the composites and the particle size of the reinforcement were analysed using X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results have shown that TiCp/Al composite with 40～70 vol. pct TiC particle reinforcement and high relative density can be directly obtained by TE/QP. TiC is the only reaction product when Al content in Al-Ti-C system is no more than 60 vol. pct, but Al3Ti phase will also form when Al content is more than 60 vol. pct. Increasing Al content prolongs the initial reaction time, reduces the highest reaction temperature and the reaction rate, and decreases the size of TiC particles. In addition, the microstructure of TiCp/Al composite and the structure of interface between TiCp and Al are studied using SEM and transmission electron microscopy （TEM）. The results show that the in-situ synthesized TiC particle has fcc cubic structure. The orientation between TiC particles and Al matrix can be described as （220）Al//（022）TiC and [112]Al//[011]TiC. Results of the mechanical property tests reveal that the ultimate strength （σ） and modulus （E） are 687 MPa and 142 GPa respectively when the Al content is 40 vol. pct. On contrary, 6 elongation increases by 3.2% with increasing Al content.
基金supported financially by the National Natural Science Foundation of China(No.51571174)the National Science Foundation for Distinguished Young Scholars for Hebei Province of China(No.E2016203376)the Hundred Excellent Innovative Talents Support Program in Hebei Province(No.SLRC2017056)。
文摘Impurity segregation even small amounts,can drastically change the cohesive properties of the grain boundaries(GB),eventually leading to intergranular embrittlement and failure of the materials,thereby effectively controlling the types and the concentrations of the impurity is very important.In this work,the nonmetallic impurities(C,H,O,N) segregation and their effects on the strength of Zr(10 1 2) GB were thoroughly investigated using first-principles calculations based on density functional theory.A comprehensive analysis of the interstitial configurations and the relative site energies indicating that C,N and O overwhelmingly prefer the octahedral sites,only H,prefers to reside in the tetrahedral sites.Moreover,the strengthening/embrittlement potency of impurity atoms on the GB was estimated using both the Rice-Wang model and first-principles tensile test calculations.The results show that all impurities,exhibit a strong segregation tendency near the GB region.The segregation of C,N and O has a remarkable strengthening effect on strength of the GB,whereas the presence of impurity H weaken the GB.Most importantly,the underlying mechanism of the strength change of the GBs due to the segregation of impurities was profoundly discussed by charge density and the bond lengths analyses,revealing that the strengthening effect especially for C-doped GB,mainly comes from an enhancement of the charge density across the GB plane.In the end,we expect that our results will be certainly useful for future theoretical and experimental investigations on Zr and its alloys.
基金supported by the Science&Technology Innovation Project of Laoshan Laboratory(No.LSKJ202203201)the Natural Science Foundation of China(32030015,32270539,32470512,32300368,32370475,32300345)+3 种基金the Young Taishan Scholar Program of Shandong Province(tsqn202408084)Inner Mongolia Natural Science Foundation(2023QN03016)Special Research Project for First-class Disciplines of the Department of Education of the Inner Mongolia Autonomous Region of China(YLXKZX-ND-039)the Ongoing Research Funding Program(ORF-2025-7),King Saud University,Riyadh,Saudi Arabia.
文摘Ciliated protists(ciliates)represent a morphologically and genetically diverse group of single-celled eukaryotes,the phylogeny of which is critical for understanding eukaryotic evolution.Through international collaborations,the Laboratory of Protozoology at Ocean University of China(OUC-group)has conducted detailed research on ciliate phylogeny based on expanded taxonomic sampling,employing single gene as well as multi-gene markers,and phylogenomic datasets.We have systematically investigated>1000 ciliate species spanning~40 orders,sampled from diverse biotopes including marine environments in China seas and freshwater wetlands.This comprehensive sampling has generated three key datasets:(1)genomic DNA extracts from~2600 strains,(2)~2300 sequences of marker genes,and(3)single-cell genomic and/or transcriptomic datasets from~120 species.Based on these datasets,the phylogenetic relationships covering all classes and most orders have been thoroughly reconstructed and investigated,resulting in the establishment of 93 new supraspecies taxa comprising two classes(Mesodiniea and Protocruziea),two subclasses(Protohypotrichia and Synhymenia),two orders(Wilbertomorphida and Lynnellida),11 families,and 76 genera.Moreover,we have reconstructed a genome-scale tree of life for ciliates and provided an updated classification of the phylum Ciliophora.Furthermore,based on the robust phylogenetic tree of ciliates,we provide more reliable estimates for the origins and divergence times of the main ciliate groups.Future studies integrating advanced genomics,innovations in culturing and interdisciplinary applications will refine the ciliate tree of life,with broader impacts for our understanding of eukaryotic evolution and biodiversity.
基金funded by the Science&Technology Innovation Project of Laoshan Laboratory(No.LSKJ202203201)the National Natural Science Foundation of China(No.32270558,31772431)+1 种基金China Postdoctoral Science Foundation(No.2024M751801)Researchers Supporting Project Number(No.RSP2024R10)King Saud University,Saudi Arabia and Young Taishan Scholar Program of Shandong Province.
文摘Psammophillic ciliates are an integral part of the foodweb despite being underrepresented in terms of molecular phylogeny and modern taxonomy.To investigate the karyorelictean group,sampling was conducted in interstitial marine habitats in China for ciliates living between the sand grains,resulting in an examination of the families Cryptopharyngidae Jankowski,1980 and Kentrophoridae Jankowski,1980.Three species,i.e.,Cryptopharynx setigerus Kahl,1928,Kentrophoros fasciolatus(Sauerbrey,1928)Foissner,1995 and K.fistulosus(Fauré-Fremiet,1950)Foissner,1995,are clearly recognized as being cosmopolitan,while other species await further recording.Phylogenetic analyses were carried out based on updated data.These revealed that the families Cryptopharyngidae and Kentrophoridae are closely related,and most genera studied are monophyletic,although Cryptopharynx qingdaoensis n.sp.is located within the Kentrophoridae branch.Brief revisions of two genera,namely Cryptopharynx Kahl,1928 and Kentrophoros Sauerbrey,1928,are provided including keys to the iden-tification of nine species belonging to the former and 12 species belonging to the latter.One new genus,Parakentrophoros n.gen.,and one new species,Cryptopharynx qingdaoensis n.sp.,are described and a new combination,Parakentrophoros canalis(Wright,1982)n.comb.,is established.Finally,it appears that the subapical oral apparatus undergoes a gradual degeneration process from Cryptopharyngidae to Kentrophoridae.
