When exposed to moderate to high temperatures,nanomaterials typically suffer from severe grain coarsening,which has long been a major concern that prevents their wider applications.Here,we proposed an effective strate...When exposed to moderate to high temperatures,nanomaterials typically suffer from severe grain coarsening,which has long been a major concern that prevents their wider applications.Here,we proposed an effective strategy to inhibit grain coarsening by constructing grain boundary(GB)complexions with multiple codoped dopants,which hindered coarsening from both energetic and kinetic perspectives.To demonstrate the feasibility of this strategy,multiple selected dopants were doped into a ZrO_(2)-SiO_(2)nanocrystalline glass ceramic(NCGC)to form GB complexions.The results showed that NCGC was predominantly composed of ZrO_(2)nanocrystallites(NCs)distributed in an amorphous SiO_(2)matrix.Ultrathin layers of GB complexions(~2.5 nm)were formed between adjacent ZrO_(2)NCs,and they were crystalline superstructures with co-segregated dopants.In addition,a small amount of quartz solid solution was formed,and it adhered to the periphery of ZrO_(2)NCs and bridged the adjacent NCs,acting as a“bridging phase”.The GB complexions and the“bridging phase”synergistically enhanced the coarsening resistance of ZrO_(2)NCs up to 1000°C.These findings are important for understanding GB complexions and are expected to provide new insights into the design of nanomaterials with excellent thermodynamic stability.展开更多
Three-dimensional atom-probe tomography and first-principles calculation combined with density functional theory were used to study the effect of the co-segregation of different elements formed during the solidificati...Three-dimensional atom-probe tomography and first-principles calculation combined with density functional theory were used to study the effect of the co-segregation of different elements formed during the solidification process of S32205 duplex stainless steel on the Cr-depleted zone at the interface between ferrite and austenite.It was found that the co-segregation of different elements formed during the solidification process of duplex stainless steel can also form Cr-depleted zone at the interface between ferrite and austenite.Moreover,Mo,Si,B,C and P atoms promote co-segregation with Cr atoms,which promotes the formation of Cr-depleted zone at the interface between ferrite and austenite in duplex stainless steel.Mo and Si strongly promote the segregation of Cr at the interface between ferrite and austenite,thereby promoting the formation of Cr-depleted zone.B,C and P elements also promote the segregation of Cr element at the interface between ferrite and austenite and the formation of Cr-depleted zone,but their effect is weaker than that of Mo and Si elements.These conclusions provide a new theoretical basis for improving the intergranular corrosion performance of duplex stainless steel.展开更多
Refractory high-entropy alloys have great potential to be utilized as high-temperature materials,and the repeatability and reproducibility of their mechanical properties are critical for practical applications.In this...Refractory high-entropy alloys have great potential to be utilized as high-temperature materials,and the repeatability and reproducibility of their mechanical properties are critical for practical applications.In this work,nevertheless,we found that the mechanical properties of the TiZrHfNb HEA greatly varied with the content of impurities in the samples even using high-purity raw materials.Specifically,the oxygen impurity is mainly responsible for the increment of the yield stress due to the strong interstitial hardening effect,whilst the ductility deterioration closely associates with the content of metalloid elements B,C,and Si.Our analysis reveals that the metalloid elements not only tend to segregate at grain boundaries but also enhance the aggregation of Zr and Ti.Such co-segregation induced the formation of strong(Zr,Ti)-metalloid bonds,resulting in grain boundary embrittlement and brittle fracture.Our current work demonstrates that the impurity contents in refractory HEAs need to be strictly controlled during production in order to improve their stability of mechanical performance.展开更多
Interactions of solute atoms in biodegradable zinc alloys and their effect on alloy mechanical properties have been less investigated.In this work,the interactions between the common solutes(Li,Mg,Mn,Cu,and Ag)used in...Interactions of solute atoms in biodegradable zinc alloys and their effect on alloy mechanical properties have been less investigated.In this work,the interactions between the common solutes(Li,Mg,Mn,Cu,and Ag)used in the biodegradable Zn alloys,including a solute-solute pair with the same element or with two different elements,are investigated based on first-principles calculations.It is found that the energetically favorable configuration is the third nearest-neighboring for most solute-solute pairs in the bulk lattice because of the relatively strong electronic interaction between solute and Zn atoms or the relatively small local elastic deformation associated with the configuration.Considering that interfacial cleavage is a key fracture mode of zinc,the segregation ability of these solutes and their effect on the{1012}twin boundary cohesion are also examined.The result shows that Li tends to fully occupy its preferred site in the twin boundary,while Mg,Mn,Cu,or Ag has a concentration limitation in the twin boundary.The twin boundary cohesion can be significantly enhanced by the segregation of Mn,followed by Cu and Ag,because of the contribution of their d states close to the Fermi level.Furthermore,the co-segregation ability of two solute atoms in the twin boundary increases with increasing the binding tendency of these two solute atoms in the boundary.Mn and Li or Mg show a relatively strong co-segregation ability in the twin boundary.Adding Mn to Zn-Li or Zn-Mg alloys can significantly enhance the resistance to fracture of twin boundaries.展开更多
The temper embrittlement of Fe-2%Mn-Sb-Ce structure steels was studied by measurements of the ductile-brittle transition temperature and observations by AES and SEM of the fracture surface of isothermally embrittle st...The temper embrittlement of Fe-2%Mn-Sb-Ce structure steels was studied by measurements of the ductile-brittle transition temperature and observations by AES and SEM of the fracture surface of isothermally embrittle steel. It shows that Sb and Mn can produce non-equilibrium co-segregation to grain boundaries and bring about the temper embrittlement of Fe-2%Mn-Sb-Ce structure steels. Cerium may reduce the temper embrittlement of the steels and the segregation of cerium to grain boundaries may play an important part in reducing the temper embrittlement of the steels.展开更多
In this work,the role of Zn content in modifying the microstructure and mechanical properties of the Mg-1.2Ca-xZn(x=0.6,2.0 wt.%,named as XZ10-0 and ZX21-0,respectively)based alloys was studied,and it is found that th...In this work,the role of Zn content in modifying the microstructure and mechanical properties of the Mg-1.2Ca-xZn(x=0.6,2.0 wt.%,named as XZ10-0 and ZX21-0,respectively)based alloys was studied,and it is found that the yield strength(YS)of the present Mg-(Zn)-Ca based alloys increases monotonically with increasing the Zn concentration,from~339 MPa in low-Zn content XZ10-0 sample to~406 MPa in high-Zn content ZX21-0 sample.Microstructure characterization shows that the enhanced YS can be attributed to the grain refinement,fine and dispersed nano-phases,a large number of lamellae structures,and the decrease of recrystallization fraction.TEM results show that the formation mechanism for the ultra-fine grains in present Mg-(Zn)-Ca based alloys can be attributed to the co-segregation of Ca and Zn elements at the grain boundary,as well as the dynamic nanoprecipitations.When the Zn content is high,the nano-phases in ZX21-0 sample belong to the Ca;Mg;Zn;ternary phases,which exert much higher thermal stability than the nano-sized Mg2 Ca binary phases formed in the low-Zn content XZ10-0 sample.The finer size and higher number density of the nano-Mg Zn Ca phases lead to the much finer grain size and sub-grain lamellae thickness in ZX21-0 sample,which thus results in the higher YS of~406 MPa.展开更多
Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,...Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.展开更多
Objective: To assess the occurrence and pattern of Toll-like receptor 4(TLR4) cosegregated genotypes among children with Plasmodium falciparum malaria in Nigeria.Methods: In this case-control study, a total of 79 Plas...Objective: To assess the occurrence and pattern of Toll-like receptor 4(TLR4) cosegregated genotypes among children with Plasmodium falciparum malaria in Nigeria.Methods: In this case-control study, a total of 79 Plasmodium falciparum infected children aged 2–7 years and 105 age-matched uninfected controls of Yoruba descents in Lagos were studied. The extracted DNA samples were used for TLR4 genotyping at codons 299(Asp > Gly) and 399(Thr > Ile) by PCR-restriction fragment length polymorphism. Malaria infection was diagnosed by blood smear microscopy and infected children were stratified into asymptomatic, uncomplicated and severe malaria sub-groups.Malnutrition was determined by measuring the mid upper arm circumference and anemia was defined as hemoglobin < 11 g/dL.Results: The proportions of children with acute malnutrition and severe anemia were12.0% and 3.2%, respectively. Parasitemia and malnutrition were not correlated and four distinct patterns of TLR4 genotypes were found in the study population: Asp299Asp/Thr399Thr(90.2%), Asp299Gly/Thr399Thr(4.3%), Gly299Gly/Thr399Thr(3.8%) and Asp299Gly/Thr399Ile(1.6%). These genotypes did not differ significantly(P > 0.05) in frequency between infected and non-infected children. However, low and high occurrences of the TLR4 Asp299Asp/Thr399 Thr and Asp299Gly/Thr399 Thr genotypes were observed in the severe malaria subgroup.Conclusions: This study reveals a protective role for TLR4 Asp299Gly/Thr399 Ile and Asp299Asp/Thr399 Thr genotypes against severe malaria in Nigerian children.展开更多
Fusarium crown rot(FCR),a chronic and severe disease caused by various Fusarium species,is prevalent in semi-arid cropping regions worldwide.One of the major QTL conferring FCR resistance was detected on chromosome ar...Fusarium crown rot(FCR),a chronic and severe disease caused by various Fusarium species,is prevalent in semi-arid cropping regions worldwide.One of the major QTL conferring FCR resistance was detected on chromosome arm 1 HL(Qcrs.cpi-1 H)in barley.To develop markers that can be reliably used to incorporate the resistance locus into breeding programs,we developed and assessed a near-isogenic line-derived population consisting of1180 recombinant inbred lines targeting the locus.Using this population,we delineated Qcrs.cpi-1 H into an interval of 0.4 c M covering a physical length of about 487 kb.Six markers co-segregating with this locus were generated.Co-linearity for genes located in this interval between the genome of barley and those of either rice or Brachypodium distachyon is poor.Three genes with non-synonymous variations between the resistant and susceptible lines were identified within the interval.The results reported in this study not only provide markers for integrating Qcrs.cpi-1 H into breeding programs,but also form a solid foundation for cloning the causal gene(s)underlying this locus.展开更多
基金the financial support of the National Natural Science Foundation of China(No.52102084)the Natural Science Foundation of Hunan Province(No.2022JJ30718)Kathryn Grandfield acknowledges funding from the Natural Sciences and Engineering Research Council of Canada(NSERC)discovery grant and research chair programs.
文摘When exposed to moderate to high temperatures,nanomaterials typically suffer from severe grain coarsening,which has long been a major concern that prevents their wider applications.Here,we proposed an effective strategy to inhibit grain coarsening by constructing grain boundary(GB)complexions with multiple codoped dopants,which hindered coarsening from both energetic and kinetic perspectives.To demonstrate the feasibility of this strategy,multiple selected dopants were doped into a ZrO_(2)-SiO_(2)nanocrystalline glass ceramic(NCGC)to form GB complexions.The results showed that NCGC was predominantly composed of ZrO_(2)nanocrystallites(NCs)distributed in an amorphous SiO_(2)matrix.Ultrathin layers of GB complexions(~2.5 nm)were formed between adjacent ZrO_(2)NCs,and they were crystalline superstructures with co-segregated dopants.In addition,a small amount of quartz solid solution was formed,and it adhered to the periphery of ZrO_(2)NCs and bridged the adjacent NCs,acting as a“bridging phase”.The GB complexions and the“bridging phase”synergistically enhanced the coarsening resistance of ZrO_(2)NCs up to 1000°C.These findings are important for understanding GB complexions and are expected to provide new insights into the design of nanomaterials with excellent thermodynamic stability.
基金supported by National Natural Science Foundation of China(Grant Nos.52004190 and 52274340).
文摘Three-dimensional atom-probe tomography and first-principles calculation combined with density functional theory were used to study the effect of the co-segregation of different elements formed during the solidification process of S32205 duplex stainless steel on the Cr-depleted zone at the interface between ferrite and austenite.It was found that the co-segregation of different elements formed during the solidification process of duplex stainless steel can also form Cr-depleted zone at the interface between ferrite and austenite.Moreover,Mo,Si,B,C and P atoms promote co-segregation with Cr atoms,which promotes the formation of Cr-depleted zone at the interface between ferrite and austenite in duplex stainless steel.Mo and Si strongly promote the segregation of Cr at the interface between ferrite and austenite,thereby promoting the formation of Cr-depleted zone.B,C and P elements also promote the segregation of Cr element at the interface between ferrite and austenite and the formation of Cr-depleted zone,but their effect is weaker than that of Mo and Si elements.These conclusions provide a new theoretical basis for improving the intergranular corrosion performance of duplex stainless steel.
基金This research was financially supported by the National Natural Science Foundation of China(Nos.11790293,52225103,51871016,52271003,52071023,52122408,and 52225103)the Funds for Creative Research Groups of China(No.51921001)+2 种基金Project of International Cooperation and Exchanges NSFC(No.52061135207,51961160729)National Key Research and Development Program of China(2022YFB4602101)Joint Project of NSFC(No.U20B2025111).
文摘Refractory high-entropy alloys have great potential to be utilized as high-temperature materials,and the repeatability and reproducibility of their mechanical properties are critical for practical applications.In this work,nevertheless,we found that the mechanical properties of the TiZrHfNb HEA greatly varied with the content of impurities in the samples even using high-purity raw materials.Specifically,the oxygen impurity is mainly responsible for the increment of the yield stress due to the strong interstitial hardening effect,whilst the ductility deterioration closely associates with the content of metalloid elements B,C,and Si.Our analysis reveals that the metalloid elements not only tend to segregate at grain boundaries but also enhance the aggregation of Zr and Ti.Such co-segregation induced the formation of strong(Zr,Ti)-metalloid bonds,resulting in grain boundary embrittlement and brittle fracture.Our current work demonstrates that the impurity contents in refractory HEAs need to be strictly controlled during production in order to improve their stability of mechanical performance.
基金The authors acknowledge the financial support from the Australian Research Council(No.DP190102373)This work was supported by computational resources provided by the Australian Gov-ernment through National Computational Infrastructure(Raijin)and Pawsey supercomputing centre(Magnus)under the National Computational Merit Allocation Scheme(NCMAS).
文摘Interactions of solute atoms in biodegradable zinc alloys and their effect on alloy mechanical properties have been less investigated.In this work,the interactions between the common solutes(Li,Mg,Mn,Cu,and Ag)used in the biodegradable Zn alloys,including a solute-solute pair with the same element or with two different elements,are investigated based on first-principles calculations.It is found that the energetically favorable configuration is the third nearest-neighboring for most solute-solute pairs in the bulk lattice because of the relatively strong electronic interaction between solute and Zn atoms or the relatively small local elastic deformation associated with the configuration.Considering that interfacial cleavage is a key fracture mode of zinc,the segregation ability of these solutes and their effect on the{1012}twin boundary cohesion are also examined.The result shows that Li tends to fully occupy its preferred site in the twin boundary,while Mg,Mn,Cu,or Ag has a concentration limitation in the twin boundary.The twin boundary cohesion can be significantly enhanced by the segregation of Mn,followed by Cu and Ag,because of the contribution of their d states close to the Fermi level.Furthermore,the co-segregation ability of two solute atoms in the twin boundary increases with increasing the binding tendency of these two solute atoms in the boundary.Mn and Li or Mg show a relatively strong co-segregation ability in the twin boundary.Adding Mn to Zn-Li or Zn-Mg alloys can significantly enhance the resistance to fracture of twin boundaries.
文摘The temper embrittlement of Fe-2%Mn-Sb-Ce structure steels was studied by measurements of the ductile-brittle transition temperature and observations by AES and SEM of the fracture surface of isothermally embrittle steel. It shows that Sb and Mn can produce non-equilibrium co-segregation to grain boundaries and bring about the temper embrittlement of Fe-2%Mn-Sb-Ce structure steels. Cerium may reduce the temper embrittlement of the steels and the segregation of cerium to grain boundaries may play an important part in reducing the temper embrittlement of the steels.
基金supported by the National Natural Science Foundation of China(Grant Nos.51701211,and 51971053)the Project of Promoting Talents in Liaoning Province(Grant No.XLYC1808038)+2 种基金the financial assistance from Young Elite Scientists Sponsorship Program by CAST(Grant Nos.2019-2021QNRC001,and 2019-2021QNRC002)the Fundamental Research Funds for the Central Universities(Grant No.N2002011)the Joint Research Fund LiaoningShenyang National Laboratory for Materials Science(Grant No.2019JH3/30100040)。
文摘In this work,the role of Zn content in modifying the microstructure and mechanical properties of the Mg-1.2Ca-xZn(x=0.6,2.0 wt.%,named as XZ10-0 and ZX21-0,respectively)based alloys was studied,and it is found that the yield strength(YS)of the present Mg-(Zn)-Ca based alloys increases monotonically with increasing the Zn concentration,from~339 MPa in low-Zn content XZ10-0 sample to~406 MPa in high-Zn content ZX21-0 sample.Microstructure characterization shows that the enhanced YS can be attributed to the grain refinement,fine and dispersed nano-phases,a large number of lamellae structures,and the decrease of recrystallization fraction.TEM results show that the formation mechanism for the ultra-fine grains in present Mg-(Zn)-Ca based alloys can be attributed to the co-segregation of Ca and Zn elements at the grain boundary,as well as the dynamic nanoprecipitations.When the Zn content is high,the nano-phases in ZX21-0 sample belong to the Ca;Mg;Zn;ternary phases,which exert much higher thermal stability than the nano-sized Mg2 Ca binary phases formed in the low-Zn content XZ10-0 sample.The finer size and higher number density of the nano-Mg Zn Ca phases lead to the much finer grain size and sub-grain lamellae thickness in ZX21-0 sample,which thus results in the higher YS of~406 MPa.
基金supported by the National Natural Science Foundation of China(Nos.11832019,11472313,11572355,and 11705264)the Science and Technology Plan Project of Guangdong Province(No.2020A0505020005)+2 种基金the Fundamental Research Funds for the Central Universities(No.19lgpy298)the State Key Laboratory of Powder MetallurgyCentral South University,Changsha,China。
文摘Grain boundaries(GBs)have critical influences on the stability and properties of various materials.In this study,first-principles calculations were performed to determine the effects of four metallic impurities(Ni,Al,Bi,and Pb)and three nonmetallic impurities(H,O,and N)on the GBs of silicon carbide(SiC),using the ∑5(210)GBs as models.The GB energy and segregation energy(SE)were calculated to identify the effects of impurities on the GB stability.Electronic interactions considerably influenced the bonding effects of SiC.The formation of weak bonds resulted in the corrosion and embrittlement of GBs.The co-segregation of Bi,Pb,and O was also investigated in detail.
文摘Objective: To assess the occurrence and pattern of Toll-like receptor 4(TLR4) cosegregated genotypes among children with Plasmodium falciparum malaria in Nigeria.Methods: In this case-control study, a total of 79 Plasmodium falciparum infected children aged 2–7 years and 105 age-matched uninfected controls of Yoruba descents in Lagos were studied. The extracted DNA samples were used for TLR4 genotyping at codons 299(Asp > Gly) and 399(Thr > Ile) by PCR-restriction fragment length polymorphism. Malaria infection was diagnosed by blood smear microscopy and infected children were stratified into asymptomatic, uncomplicated and severe malaria sub-groups.Malnutrition was determined by measuring the mid upper arm circumference and anemia was defined as hemoglobin < 11 g/dL.Results: The proportions of children with acute malnutrition and severe anemia were12.0% and 3.2%, respectively. Parasitemia and malnutrition were not correlated and four distinct patterns of TLR4 genotypes were found in the study population: Asp299Asp/Thr399Thr(90.2%), Asp299Gly/Thr399Thr(4.3%), Gly299Gly/Thr399Thr(3.8%) and Asp299Gly/Thr399Ile(1.6%). These genotypes did not differ significantly(P > 0.05) in frequency between infected and non-infected children. However, low and high occurrences of the TLR4 Asp299Asp/Thr399 Thr and Asp299Gly/Thr399 Thr genotypes were observed in the severe malaria subgroup.Conclusions: This study reveals a protective role for TLR4 Asp299Gly/Thr399 Ile and Asp299Asp/Thr399 Thr genotypes against severe malaria in Nigerian children.
基金partially supported by the Grains Research and Development Corporation,Australia(CFF00010)University of Tasmania,Australiathe China Scholarship Council for financial supports。
文摘Fusarium crown rot(FCR),a chronic and severe disease caused by various Fusarium species,is prevalent in semi-arid cropping regions worldwide.One of the major QTL conferring FCR resistance was detected on chromosome arm 1 HL(Qcrs.cpi-1 H)in barley.To develop markers that can be reliably used to incorporate the resistance locus into breeding programs,we developed and assessed a near-isogenic line-derived population consisting of1180 recombinant inbred lines targeting the locus.Using this population,we delineated Qcrs.cpi-1 H into an interval of 0.4 c M covering a physical length of about 487 kb.Six markers co-segregating with this locus were generated.Co-linearity for genes located in this interval between the genome of barley and those of either rice or Brachypodium distachyon is poor.Three genes with non-synonymous variations between the resistant and susceptible lines were identified within the interval.The results reported in this study not only provide markers for integrating Qcrs.cpi-1 H into breeding programs,but also form a solid foundation for cloning the causal gene(s)underlying this locus.
