The excellent strength-ductility combination of hetero-grained Mg alloys has been reported to stem from pronounced hetero-deformation induced(HDI)stress.This stress alters the internal stress state of various slip sys...The excellent strength-ductility combination of hetero-grained Mg alloys has been reported to stem from pronounced hetero-deformation induced(HDI)stress.This stress alters the internal stress state of various slip systems and triggers significant activity of non-basal slips.However,the HDI stress state of different slip systems,and the mechanisms underlying the selective activation between basal and non-basal slips remain unclear to date.This study develops a novel HDI stress partitioning framework that in-situ calculates the crystallographic parameters and geometrical information of each datapoint within grains,aiming to reveal the correlation between HDI stress partitioning on individual slip systems and localized deformation model in the case of bimodal-grained ZK60 alloy.The framework demonstrates that HDI stress shows a strong dependence on the density of geometrically necessary dislocations(GNDs)and slip-system-level grain size,while exhibiting a relatively weaker correlation with equivalent-circle size of the hetero-grains.Given the close relation between the stress partitioning and the physical parameters,the framework can accurately predict the single and multiple slip activity fields obtained from highresolution digital image correlation(HR-DIC).This holds even for slip systems with low Schmid factors,which are theoretically difficult to activate.Using this framework,it is found that HDI stress plays a more prominent role in diminishing the effective resolved shear stress(RSS)of basaland prismatic(i.e.,component)dislocations,while having a negligible effect on pyramidal<c+a>slips.Benefiting from the increased ratio of RSS_(<c+a>)/RSS_(),pyramidal<c+a>dislocations are extensively activated,leading to excellent strength-ductility combination in the bimodal-grained ZK60 alloy.展开更多
Cryogenic rolling experiments have been conducted on the AZ31 magnesium(Mg)alloy sheet with bimodal non-basal texture,which is fabricated via the newly developed equal channel angular rolling and continuous bending pr...Cryogenic rolling experiments have been conducted on the AZ31 magnesium(Mg)alloy sheet with bimodal non-basal texture,which is fabricated via the newly developed equal channel angular rolling and continuous bending process with subsequent annealing(ECAR-CB-A)process.Results demonstrate that this sheet shows no edge cracks until the accumulated thickness reduction reaches about 18.5%,which is about 105.6%larger than that of the sheet with traditional basal texture.Characterization experiments including optical microstructure(OM),X-ray diffractometer(XRD),and electron backscatter diffraction(EBSD)measurements are then performed to explore the microstructure characteristics,texture evolution and deformation mechanisms during cryogenic rolling.Experimental observations confirm the occurrence of abundant{10–12}extension twins(ETs),twin-twin interactions among{10–12}ET variants and{10–12}-{10–12}double twins(DTs).The twinning behaviors as for{10–12}ETs are responsible for the concentration of c-axes of grains towards normal direction(ND)and the formation of transverse direction(TD)-component texture at the beginning of cryogenic rolling.The twinning behaviors with respect to{10–12}-{10–12}DTs are responsible for the disappearance of TD-component texture at the later stage of cryogenic rolling.The involved deformation mechanisms can be summarized as follows:Firstly{10–12}ETs dominate the plastic deformation.Subsequently,dislocation slip,especially basalslip,starts to sustain more plastic strain,while{10–12}ETs occur more frequently and enlarge continuously,resulting in the formation of twin-twin interaction among{10–12}ET variants.With the increasing rolling passes,{10–12}-{10–12}DTs incorporate in the plastic deformation and dislocation slip serves as the major one to sustain plastic strain.The activities of basalslip,{10–12}ETs and{10–12}-{10–12}DTs benefit in accommodating the plastic strain in sheet thickness,which contributes to the improved rolling formability in AZ31 Mg alloy sheet with bimodal non-basal texture during cryogenic rolling.展开更多
The relationship between activities of involved deformation mechanisms and the evolution of microstructure and texture during uniaxial tension of AZ31 magnesium alloy with a rare non-basal texture has been thoroughly ...The relationship between activities of involved deformation mechanisms and the evolution of microstructure and texture during uniaxial tension of AZ31 magnesium alloy with a rare non-basal texture has been thoroughly investigated in the present study by means of electron backscattered diffraction(EBSD) measurement and visco-plastic self-consistent(VPSC) modeling. These results show that except basal slip and prismatic slip, {10■2} extension twin(ET) also plays a significant role during plastic deformation. With the increasing tilted angle between loading direction and rolling direction(RD) of sheet, the activity of {10■2} ET possesses a decreasing tendency and its role in plastic deformation changes from the one mainly sustaining plastic strain to the one mainly accommodating local strain between individual grains. When {10■2} ET serves as a carrier of plastic strain, it mainly results in the formation of basal texture component(c-axis//ND, normal direction). By comparison, when the role of {10■2} ET is to accommodate local strain, it mainly brings about the formation of prismatic texture component(c-axis//TD, transverse direction). At large plastic deformation, the competition between basal slip and pyramidal<c+a> slip is responsible for the concentration of tilted basal poles towards ND within all deformed samples. The larger difference is between the activities of basal slip and pyramidal <c+a> slip, the smaller separation is between these two tilted basal poles. Besides,VPSC modeling overesttmates volume fractions of {10■2} ET in samples with angle of 0 to 30° between loading direction and RD of sheet because interactions between twin variants are not included in VPSC modeling procedure at the present form. In addition, as compatible deformation between individual grains cannot be considered in VPSC modeling, the predicted volume fractions of {10■2} ET in samples with angle of 45 to 90° between loading direction and RD of sheet are smaller than the correspondingly measured results.展开更多
In-plane uniaxial tension of AZ31 magnesium alloy sheet with non-basal texture has been conducted in order to demonstrate the effects of loading direction on the microstructure evolution and mechanical properties at a...In-plane uniaxial tension of AZ31 magnesium alloy sheet with non-basal texture has been conducted in order to demonstrate the effects of loading direction on the microstructure evolution and mechanical properties at ambient temperature.Loading axes are chosen to be along five directions distributed between rolling direction(RD)and transverse direction(TD),allowing various activities in involved slip and twinning modes to take place.As for twinning modes,electron backscattered diffraction observations confirm that the contribution of{1011}compression twinning is minimal to the plastic deformation of all deformed samples.By comparison,{1012}extension twinning(ET)not only serves as an important carrier on sustaining and accommodating plastic strain but also contributes to the emergence of TD-component texture with the progression of plastic strain.In terms of slip modes,analysis on Schmid factor demonstrates that the increasing tilted angle between loading direction and RD of sheet is unfavorable to the activation of basalslip,whereas it contributes to the activation of prismaticslip.These observations consequently explain the increasing tendency of 0.2%proof yield stress.Moreover,the activations of basalslip and{1012}ET collectively contribute to the concentration of two tilted basal poles toward normal direction.With increasing angle between loading direction and RD,the activations of basalslip and{1012}ET are gradually weakened.This leads to a weakening tendency about concentration of two tilted basal poles,a generally increasing tendency about Lankford value(r-value)and a generally decreasing tendency about strain-hardening exponent(n-value).展开更多
Two novel types of irrational orientation relationships(ORs)betweenβ-Mg_(2)Sn precipitates and theα-Mg matrix were observed in a Mg-4 Sn alloy aged at 160℃.In contrast to that for the dominantβ-Mg_(2)Sn laths lyin...Two novel types of irrational orientation relationships(ORs)betweenβ-Mg_(2)Sn precipitates and theα-Mg matrix were observed in a Mg-4 Sn alloy aged at 160℃.In contrast to that for the dominantβ-Mg_(2)Sn laths lying on the(0001)_αbasal plane of the matrix,the precipitates with the irrational ORs are inclined or normal to(0001)_α.Specifically,the precipitates that adopt the OR of[011]_(β)//[2110]_α,with(111)_(β)deviating approximately 4.7°from(0002)_α,have a long axis parallel to[0001]_α.The precipitates with the OR of[011]_(β)//[2110]_α,with(111)_(β)deviating approximately 13.50 from(0002)_α,exhibit a long axis of[0211]_α.Both types of precipitates have a habit plane(HP)of(2110)_α.The interface orientations of the precipitates associated with the irrational ORs are interpreted by a good matching sites(GMS)method.A thorough examination of the crystallographic features of theβ-Mg_(2)Sn precipitates in the literature shows that the precipitates with most rational ORs have a HP parallel to(0001)_α,and those with most irrational ORs have a HP(or long axis)inclined or normal to(0001)_α.The preferences of the precipitates with different irrational ORs have also been analyzed by examining the lattice matching condition across the interfaces between the precipitates and the matrix.展开更多
Objective:Triple-negative breast cancer(estrogen receptor-negative,progesterone receptor-negative and Her2-negative) can be classified into two subtypes:basal and non-basal phenotype.And the basal phenotype is associa...Objective:Triple-negative breast cancer(estrogen receptor-negative,progesterone receptor-negative and Her2-negative) can be classified into two subtypes:basal and non-basal phenotype.And the basal phenotype is associated with poor outcome.The purpose of this study was to figure out the differences of clinicopathological characters and related factors of prognosis between these two subtypes.Methods:Immunohistochemical staining was performed for the CK5/6,CK17 basal markers and EGFR on biopsy samples from 40 triple-negative patients and the clinicopathology features of these samples were investigated.Results:Seventy percent of the patients were diagnosed as the basal phenotype.Compared with the non-basal phenotype,the basal phenotype lesions were significantly larger in diameter with a high nuclear grade.In the node-negative group the basal phenotype clearly showed the same clinicopathological differences.There was statistically significant concordance among all three antibodies.Conclusion:Expression of basal markers identifies a biologically and clinically distinct subgroup of TN tumors,justifying the use of basal markers to define the basal or the non-basal phenotype.It is important to help the doctor deciding the therapeutic strategy for patient with triple-negative breast cancer.展开更多
Here we firstly report a series of new deep eutectic solvents(DESs) induced by small amounts of crown ether complex and mainly formed by polyethylene glycol. These DESs not only presented the ultra-deep extraction of ...Here we firstly report a series of new deep eutectic solvents(DESs) induced by small amounts of crown ether complex and mainly formed by polyethylene glycol. These DESs not only presented the ultra-deep extraction of non-basic N-compounds from fuel oils, but also opened up the possibility of other new applications in chemistry and materials science.展开更多
Since mid-2016,the low pathogenic H7N9 influenza virus has evolved into a highly pathogenic(HP)phenotype in China,raising many concerns about public health and poultry industry.The insertion of a“KRTA”motif at hemag...Since mid-2016,the low pathogenic H7N9 influenza virus has evolved into a highly pathogenic(HP)phenotype in China,raising many concerns about public health and poultry industry.The insertion of a“KRTA”motif at hemagglutinin cleavage site(HACS)occurred in the early stage of HP H7N9 variants.During the co-circulation,the HACS of HP-H7N9 variants were more polymorphic in birds and humans.Although HP-H7N9 variants,unlike the H5 subtype virus,exhibited the insertions of basic and non-basic amino acids,the underlying function of those insertions and substitutions remains unclear.The results of bioinformatics analysis indicated that the PEVPKRKRTAR/G motif of HACS had become the dominant motif in China.Then,we generated six H7N9 viruses bearing the PEIPKGR/G,PEVPKGR/G,PEVPKRKRTAR/G,PEVPKGKRTAR/G,PEVPKGKRIAR/G,and PEVPKRKRR/G motifs.Interestingly,after the deletion of threonine and alanine(TA)at HACS,the H7N9 viruses manifested decreased thermostability and virulence in mice,and the PEVPKRKRTAR/G-motif virus is prevalent in birds and humans probably due to its increased transmissibility and moderate virulence.By contrast,the insertion of non-basic amino acid isoleucine and alanine(IA)decreased the transmissibility in chickens and virulence in mice.Remarkably,the I335V substitution of H7N9 virus enhanced infectivity and transmission in chickens,suggesting that the combination of mutations and insertions of amino acids at the HACS promoted replication and pathogenicity in chickens and mice.The ongoing evolution of H7N9 increasingly threatens public health and poultry industry,so,its comprehensive surveillance and prevention of H7N9 viruses should be pursued.展开更多
The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe ...The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe plastic deformation(SPD)technique,refines microstructures by generating fine grains,uniformly dispersed fragmented particles,and a high fraction of high-angle grain boundaries(HAGBs),thereby facilitating superplastic forming at high strain rates and low temperatures.In the present work,a dual eccentric-pin tool(DEPT)FSP was employed to incorporate ZrO_(2) particles into a 6 mm thick AZ91D Mg alloy,leading to the formation of high volume{10-12}twins,dislocations,and β-Mg_(17)Al_(12) precipitates within the stirred zone.The microstructural evolution and mechanical behaviour of the stir zone under various process parameters were analysed using scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The DEPT enhanced plastic shearing and dynamic recrystallization,significantly reducing the grain size from 15.6μm to 2.35μm while promoting uniform dislocation distribution within the stir zone(SZ).Grain orientation analysis revealed a transition from basal to prismatic texture dominance(29.3% volume fraction)due to intensified radial-tangential coupling shear deformation,facilitating the activation of non-basal slip systems.The DEPT evidently improved the hardness of the SZ from 58 to 92 HV and increased tensile strength from 234 MPa to 325 MPa while maintaining an elongation of 23.8%,achieving an optimal strengthductility balance.This work presents a one-step approach for tailoring microstructural heterogeneity and enhancing mechanical properties in AZ91D/ZrO_(2) composites using the DEPT FSP technique.The method provides an effective strategy for mitigating the strength-ductility trade-off commonly observed in Mg alloys.展开更多
Many properties of Mg matrix composites are mutually incompatible,and even completely repel each other.Here,we constructed a magnetic layered component in Mg matrix composite reinforced with reduced graphene oxide(RGO...Many properties of Mg matrix composites are mutually incompatible,and even completely repel each other.Here,we constructed a magnetic layered component in Mg matrix composite reinforced with reduced graphene oxide(RGO)through an in-situ interface reaction strategy,achieving simultaneous improvement in the strength,ductility,and electromagnetic shielding performance of the composite.The magnetic component is generated by the in-situ reaction of Fe_(2)O_(3)nanoparticles encapsulated on RGO with the Mg matrix.The superior strength-ductility synergy originates from layered heterostructure,which actives non-basal dislocations and enables a stable microcrackmultiplication.The heterogeneous layered structure strengthens the multi-level reflection of electromagnetic wave(EMW)inside the composite.The in-situ interfacial reaction introduces abundant of heterogeneous interfaces into the composites,which improves the interfacial polarization loss ability of the composites.The magnetic RGO layer can provide shape anisotropy that breaks the Snoek limit,thus improving the magnetic loss ability of composite in high-frequency electromagnetic fields.The synergistic action of multiple EMW loss mechanisms improves the electromagnetic shielding performance of composite.The current study emphasizes the influence of interface structure on the mechanical and functional properties of composites,and presents a promising approach for the development of structure/functional integrated composites with enhanced properties.展开更多
The rolling direction（RD） and the transverse direction（TD） samples were obtained from an as-rolled ZK60 magnesium alloy sheet with strong anisotropy of initial texture and their mechanical properties were tested a...The rolling direction（RD） and the transverse direction（TD） samples were obtained from an as-rolled ZK60 magnesium alloy sheet with strong anisotropy of initial texture and their mechanical properties were tested at various deformation temperatures. Meanwhile, the microstructure and texture of these samples after fracture were investigated. Results revealed that a higher flow stress along the RD than that along the TD at room temperature were ascribed to the strong anisotropy of transitional texture, and this texture effect was remarkably weakened with the increase of deformation temperature. Deformation structure was dominant at 100℃, and was replaced by dynamic recrystallization structure when the deformation temperature increased to 200℃ and 300℃. The texture presented a strong texture（transitional texture in the RD sample and basal texture in the TD sample） at 100℃, but its intensity visibly decreased and texture components became more disperse at 200℃ and 300℃. These microstructure and texture results were employed in conjunction with calculated results to argue that raising deformation temperature could increase the activity of non-basal slip by tailoring the relative critical resolved shear stress of each deformation mode and finally result in low texture effect on mechanical anisotropy.展开更多
Due to the insufficient slip systems,Mg and its alloys exhibit poor ductility during plastic deformation at room temperature.To solve this problem,alloying is considered as a most effective method to improve the ducti...Due to the insufficient slip systems,Mg and its alloys exhibit poor ductility during plastic deformation at room temperature.To solve this problem,alloying is considered as a most effective method to improve the ductility of Mg alloys,which attracts wide attentions of industries.However,it is still a challenge to understand the ductilization mechanism,because of the complicated alloying elements and their interactions with Mg matrix.In this work,pure Mg and Mg-Y alloys were comparatively studied to investigate the effect of Y addition on microstructure evolution and mechanical properties.A huge increase of uniform elongation,from 5.3%to 20.7%,was achieved via only 3 wt%addition of yttrium.TEM results revealed that the only activated slip system in pure Mg was basalslip,led to its poor ductility at room temperature.In contrast,a large number of stacking faults and non-basal dislocations with<c>component were observed in the deformed Mg-Y alloy,which was proposed as the main reason for significant improvement of strain hardening and ductility.High resolution TEM indicated that most of the stacking faults were II and 12 intrinsic faults,which played a critical role in improving the ductility of Mg-Y alloy.Addition of Y into Mg alloy decreased the stacking fault energy,which induced high density stacking faults in the grain interior.展开更多
Deformation behavior of 1 Al containing Mg alloy has been investigated in the present study.After annealing,the Mg-1 Al alloy shows a typical basal texture.When compared to the pure Mg having a similar texture and gra...Deformation behavior of 1 Al containing Mg alloy has been investigated in the present study.After annealing,the Mg-1 Al alloy shows a typical basal texture.When compared to the pure Mg having a similar texture and grain size,the Mg-1 Al alloy shows much higher strength and larger elongation.Slip trace analyses of the tensile strained specimens show that non-basal slips such as pyramidal I and II slips can be easily activated at an early stage of deformation in the Mg-1 Al alloy and the grains in the Mg-1 Al alloy are seen to accommodate a larger degree of deformation than those in the pure Mg at a given strain.With increasing tensile strain,however,there is a strain localization along the initially formed slip lines of non-basal slips,forming surface steps without activating multiple slip lines.展开更多
基金the National Natural Science Foundation of China(No.52305385,U23A20541,52471131,52201057)the University Natural Science Research Project of Anhui Province(No.2022AH050316).
文摘The excellent strength-ductility combination of hetero-grained Mg alloys has been reported to stem from pronounced hetero-deformation induced(HDI)stress.This stress alters the internal stress state of various slip systems and triggers significant activity of non-basal slips.However,the HDI stress state of different slip systems,and the mechanisms underlying the selective activation between basal and non-basal slips remain unclear to date.This study develops a novel HDI stress partitioning framework that in-situ calculates the crystallographic parameters and geometrical information of each datapoint within grains,aiming to reveal the correlation between HDI stress partitioning on individual slip systems and localized deformation model in the case of bimodal-grained ZK60 alloy.The framework demonstrates that HDI stress shows a strong dependence on the density of geometrically necessary dislocations(GNDs)and slip-system-level grain size,while exhibiting a relatively weaker correlation with equivalent-circle size of the hetero-grains.Given the close relation between the stress partitioning and the physical parameters,the framework can accurately predict the single and multiple slip activity fields obtained from highresolution digital image correlation(HR-DIC).This holds even for slip systems with low Schmid factors,which are theoretically difficult to activate.Using this framework,it is found that HDI stress plays a more prominent role in diminishing the effective resolved shear stress(RSS)of basaland prismatic(i.e.,component)dislocations,while having a negligible effect on pyramidal<c+a>slips.Benefiting from the increased ratio of RSS_(<c+a>)/RSS_(),pyramidal<c+a>dislocations are extensively activated,leading to excellent strength-ductility combination in the bimodal-grained ZK60 alloy.
基金supported by the National Natural Science Foundation of China(Grant Nos.51805064,51822509)the Qingnian project of science and technology research program of Chongqing Education Commission of China(Grant No.KJQN202101141).
文摘Cryogenic rolling experiments have been conducted on the AZ31 magnesium(Mg)alloy sheet with bimodal non-basal texture,which is fabricated via the newly developed equal channel angular rolling and continuous bending process with subsequent annealing(ECAR-CB-A)process.Results demonstrate that this sheet shows no edge cracks until the accumulated thickness reduction reaches about 18.5%,which is about 105.6%larger than that of the sheet with traditional basal texture.Characterization experiments including optical microstructure(OM),X-ray diffractometer(XRD),and electron backscatter diffraction(EBSD)measurements are then performed to explore the microstructure characteristics,texture evolution and deformation mechanisms during cryogenic rolling.Experimental observations confirm the occurrence of abundant{10–12}extension twins(ETs),twin-twin interactions among{10–12}ET variants and{10–12}-{10–12}double twins(DTs).The twinning behaviors as for{10–12}ETs are responsible for the concentration of c-axes of grains towards normal direction(ND)and the formation of transverse direction(TD)-component texture at the beginning of cryogenic rolling.The twinning behaviors with respect to{10–12}-{10–12}DTs are responsible for the disappearance of TD-component texture at the later stage of cryogenic rolling.The involved deformation mechanisms can be summarized as follows:Firstly{10–12}ETs dominate the plastic deformation.Subsequently,dislocation slip,especially basalslip,starts to sustain more plastic strain,while{10–12}ETs occur more frequently and enlarge continuously,resulting in the formation of twin-twin interaction among{10–12}ET variants.With the increasing rolling passes,{10–12}-{10–12}DTs incorporate in the plastic deformation and dislocation slip serves as the major one to sustain plastic strain.The activities of basalslip,{10–12}ETs and{10–12}-{10–12}DTs benefit in accommodating the plastic strain in sheet thickness,which contributes to the improved rolling formability in AZ31 Mg alloy sheet with bimodal non-basal texture during cryogenic rolling.
基金the National Natural Science Foundation of China(Grant Nos.51805064,51701034,51822509)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant Nos.KJQN201801137)the Basic and Advanced Research Project of CQ CSTC(Grant Nos.cstc2017jcyj AX0062,cstc2018jcyj AX0035)。
文摘The relationship between activities of involved deformation mechanisms and the evolution of microstructure and texture during uniaxial tension of AZ31 magnesium alloy with a rare non-basal texture has been thoroughly investigated in the present study by means of electron backscattered diffraction(EBSD) measurement and visco-plastic self-consistent(VPSC) modeling. These results show that except basal slip and prismatic slip, {10■2} extension twin(ET) also plays a significant role during plastic deformation. With the increasing tilted angle between loading direction and rolling direction(RD) of sheet, the activity of {10■2} ET possesses a decreasing tendency and its role in plastic deformation changes from the one mainly sustaining plastic strain to the one mainly accommodating local strain between individual grains. When {10■2} ET serves as a carrier of plastic strain, it mainly results in the formation of basal texture component(c-axis//ND, normal direction). By comparison, when the role of {10■2} ET is to accommodate local strain, it mainly brings about the formation of prismatic texture component(c-axis//TD, transverse direction). At large plastic deformation, the competition between basal slip and pyramidal<c+a> slip is responsible for the concentration of tilted basal poles towards ND within all deformed samples. The larger difference is between the activities of basal slip and pyramidal <c+a> slip, the smaller separation is between these two tilted basal poles. Besides,VPSC modeling overesttmates volume fractions of {10■2} ET in samples with angle of 0 to 30° between loading direction and RD of sheet because interactions between twin variants are not included in VPSC modeling procedure at the present form. In addition, as compatible deformation between individual grains cannot be considered in VPSC modeling, the predicted volume fractions of {10■2} ET in samples with angle of 45 to 90° between loading direction and RD of sheet are smaller than the correspondingly measured results.
基金supported by the National Natural Science Foundation of China(Grant Nos.51805064,51822509,51701034)the Scientifi c and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJQN201801137)+1 种基金the Basic and Advanced Research Project of Chongqing Science and Technology Commission(Grant Nos.cstc2017jcyjAX0062,cstc2018jcyjAX0035)the Chongqing University Key Laboratory of Micro/Nano Materials Engineering and Technology(Grant No.KFJJ2003)。
文摘In-plane uniaxial tension of AZ31 magnesium alloy sheet with non-basal texture has been conducted in order to demonstrate the effects of loading direction on the microstructure evolution and mechanical properties at ambient temperature.Loading axes are chosen to be along five directions distributed between rolling direction(RD)and transverse direction(TD),allowing various activities in involved slip and twinning modes to take place.As for twinning modes,electron backscattered diffraction observations confirm that the contribution of{1011}compression twinning is minimal to the plastic deformation of all deformed samples.By comparison,{1012}extension twinning(ET)not only serves as an important carrier on sustaining and accommodating plastic strain but also contributes to the emergence of TD-component texture with the progression of plastic strain.In terms of slip modes,analysis on Schmid factor demonstrates that the increasing tilted angle between loading direction and RD of sheet is unfavorable to the activation of basalslip,whereas it contributes to the activation of prismaticslip.These observations consequently explain the increasing tendency of 0.2%proof yield stress.Moreover,the activations of basalslip and{1012}ET collectively contribute to the concentration of two tilted basal poles toward normal direction.With increasing angle between loading direction and RD,the activations of basalslip and{1012}ET are gradually weakened.This leads to a weakening tendency about concentration of two tilted basal poles,a generally increasing tendency about Lankford value(r-value)and a generally decreasing tendency about strain-hardening exponent(n-value).
基金the Major Science and Technology Project of Sichuan Province(Grant No.2020ZDZX0011)the Fundamental Research Funds for the Central Universities。
文摘Two novel types of irrational orientation relationships(ORs)betweenβ-Mg_(2)Sn precipitates and theα-Mg matrix were observed in a Mg-4 Sn alloy aged at 160℃.In contrast to that for the dominantβ-Mg_(2)Sn laths lying on the(0001)_αbasal plane of the matrix,the precipitates with the irrational ORs are inclined or normal to(0001)_α.Specifically,the precipitates that adopt the OR of[011]_(β)//[2110]_α,with(111)_(β)deviating approximately 4.7°from(0002)_α,have a long axis parallel to[0001]_α.The precipitates with the OR of[011]_(β)//[2110]_α,with(111)_(β)deviating approximately 13.50 from(0002)_α,exhibit a long axis of[0211]_α.Both types of precipitates have a habit plane(HP)of(2110)_α.The interface orientations of the precipitates associated with the irrational ORs are interpreted by a good matching sites(GMS)method.A thorough examination of the crystallographic features of theβ-Mg_(2)Sn precipitates in the literature shows that the precipitates with most rational ORs have a HP parallel to(0001)_α,and those with most irrational ORs have a HP(or long axis)inclined or normal to(0001)_α.The preferences of the precipitates with different irrational ORs have also been analyzed by examining the lattice matching condition across the interfaces between the precipitates and the matrix.
基金Supported by a grant from the National Natural Science Foundation of Hubei Province (No.2009CDB063)
文摘Objective:Triple-negative breast cancer(estrogen receptor-negative,progesterone receptor-negative and Her2-negative) can be classified into two subtypes:basal and non-basal phenotype.And the basal phenotype is associated with poor outcome.The purpose of this study was to figure out the differences of clinicopathological characters and related factors of prognosis between these two subtypes.Methods:Immunohistochemical staining was performed for the CK5/6,CK17 basal markers and EGFR on biopsy samples from 40 triple-negative patients and the clinicopathology features of these samples were investigated.Results:Seventy percent of the patients were diagnosed as the basal phenotype.Compared with the non-basal phenotype,the basal phenotype lesions were significantly larger in diameter with a high nuclear grade.In the node-negative group the basal phenotype clearly showed the same clinicopathological differences.There was statistically significant concordance among all three antibodies.Conclusion:Expression of basal markers identifies a biologically and clinically distinct subgroup of TN tumors,justifying the use of basal markers to define the basal or the non-basal phenotype.It is important to help the doctor deciding the therapeutic strategy for patient with triple-negative breast cancer.
基金supported by the National Natrual Sciece Foundation of China (Nos. 21650110454, 21675164, 2 822407)the CAS-President International Fellowship Initiative (No. 2017PC0014)the Funds for Distinguished Young Scientists of Gansu (No. 1506RJDA281)
文摘Here we firstly report a series of new deep eutectic solvents(DESs) induced by small amounts of crown ether complex and mainly formed by polyethylene glycol. These DESs not only presented the ultra-deep extraction of non-basic N-compounds from fuel oils, but also opened up the possibility of other new applications in chemistry and materials science.
基金supported by National Natural Science Foundation of China(31672586 and 31830097)the Key Research and Development Program of Guangdong Province(2019B020218004)+2 种基金Earmarked Found for China Agriculture Research System(CARS-41-G16)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2018,Wenbao Qi)Young Scholars of Yangtze River Scholar Professor Program(2019,Wenbao Qi)
文摘Since mid-2016,the low pathogenic H7N9 influenza virus has evolved into a highly pathogenic(HP)phenotype in China,raising many concerns about public health and poultry industry.The insertion of a“KRTA”motif at hemagglutinin cleavage site(HACS)occurred in the early stage of HP H7N9 variants.During the co-circulation,the HACS of HP-H7N9 variants were more polymorphic in birds and humans.Although HP-H7N9 variants,unlike the H5 subtype virus,exhibited the insertions of basic and non-basic amino acids,the underlying function of those insertions and substitutions remains unclear.The results of bioinformatics analysis indicated that the PEVPKRKRTAR/G motif of HACS had become the dominant motif in China.Then,we generated six H7N9 viruses bearing the PEIPKGR/G,PEVPKGR/G,PEVPKRKRTAR/G,PEVPKGKRTAR/G,PEVPKGKRIAR/G,and PEVPKRKRR/G motifs.Interestingly,after the deletion of threonine and alanine(TA)at HACS,the H7N9 viruses manifested decreased thermostability and virulence in mice,and the PEVPKRKRTAR/G-motif virus is prevalent in birds and humans probably due to its increased transmissibility and moderate virulence.By contrast,the insertion of non-basic amino acid isoleucine and alanine(IA)decreased the transmissibility in chickens and virulence in mice.Remarkably,the I335V substitution of H7N9 virus enhanced infectivity and transmission in chickens,suggesting that the combination of mutations and insertions of amino acids at the HACS promoted replication and pathogenicity in chickens and mice.The ongoing evolution of H7N9 increasingly threatens public health and poultry industry,so,its comprehensive surveillance and prevention of H7N9 viruses should be pursued.
基金the financial support from the Shandong Provincial Science Foundation for Outstanding Young Scholars(Grant No ZR2024YQ020)the National Natural Science Foundation of China(Grant Nos.52275349 and 52035005)+3 种基金the National Key Research and Development Program of China(Grant No 2022YFB4600902)the Excellent Young Team Project of Central Universities(No.2023QNTD002)Key Research and Development Program of Shandong Province(Grant No 2021ZLGX01)sponsored by the China/Shandong University International Postdoctoral Exchange Program.
文摘The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe plastic deformation(SPD)technique,refines microstructures by generating fine grains,uniformly dispersed fragmented particles,and a high fraction of high-angle grain boundaries(HAGBs),thereby facilitating superplastic forming at high strain rates and low temperatures.In the present work,a dual eccentric-pin tool(DEPT)FSP was employed to incorporate ZrO_(2) particles into a 6 mm thick AZ91D Mg alloy,leading to the formation of high volume{10-12}twins,dislocations,and β-Mg_(17)Al_(12) precipitates within the stirred zone.The microstructural evolution and mechanical behaviour of the stir zone under various process parameters were analysed using scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The DEPT enhanced plastic shearing and dynamic recrystallization,significantly reducing the grain size from 15.6μm to 2.35μm while promoting uniform dislocation distribution within the stir zone(SZ).Grain orientation analysis revealed a transition from basal to prismatic texture dominance(29.3% volume fraction)due to intensified radial-tangential coupling shear deformation,facilitating the activation of non-basal slip systems.The DEPT evidently improved the hardness of the SZ from 58 to 92 HV and increased tensile strength from 234 MPa to 325 MPa while maintaining an elongation of 23.8%,achieving an optimal strengthductility balance.This work presents a one-step approach for tailoring microstructural heterogeneity and enhancing mechanical properties in AZ91D/ZrO_(2) composites using the DEPT FSP technique.The method provides an effective strategy for mitigating the strength-ductility trade-off commonly observed in Mg alloys.
基金supported by Yunnan Major Scientific and Technological Projects(grant No 202202AG050004,202202AG050011)the National Natural Science Foundation of China(grant No 52061021)Yunnan Industrial Technology Innovation Talent Project.
文摘Many properties of Mg matrix composites are mutually incompatible,and even completely repel each other.Here,we constructed a magnetic layered component in Mg matrix composite reinforced with reduced graphene oxide(RGO)through an in-situ interface reaction strategy,achieving simultaneous improvement in the strength,ductility,and electromagnetic shielding performance of the composite.The magnetic component is generated by the in-situ reaction of Fe_(2)O_(3)nanoparticles encapsulated on RGO with the Mg matrix.The superior strength-ductility synergy originates from layered heterostructure,which actives non-basal dislocations and enables a stable microcrackmultiplication.The heterogeneous layered structure strengthens the multi-level reflection of electromagnetic wave(EMW)inside the composite.The in-situ interfacial reaction introduces abundant of heterogeneous interfaces into the composites,which improves the interfacial polarization loss ability of the composites.The magnetic RGO layer can provide shape anisotropy that breaks the Snoek limit,thus improving the magnetic loss ability of composite in high-frequency electromagnetic fields.The synergistic action of multiple EMW loss mechanisms improves the electromagnetic shielding performance of composite.The current study emphasizes the influence of interface structure on the mechanical and functional properties of composites,and presents a promising approach for the development of structure/functional integrated composites with enhanced properties.
基金supported by the Fund for Distinguished Young Scholars of China Academy of Space Technology(No.2021399)the National Natural Science Foundation of China(No.51805064)the Science and Technology Research Program of Chongqing Municipal Education Commission,China(No.KJQN202101141)。
基金the National Natural Science Foundation of China(Nos.51704209,U1810208,U1810122)the Central Government Guided Local Science and Technology Development Projects,China(No.YDZJSX2021A010)+5 种基金the Projects of International Cooperation in Shanxi Province,China(Nos.201803D421086,201903D421076)Shanxi Province Patent Promotion Implementation Fund,China(No.20200718)the Technological Innovation Programs of Higher Education Institutions in Shanxi Province,China(No.201802034)Shanxi Province Scientific Facilities and Instruments Shared Service Platform of Magnesium-based Materials Electric Impulse Aided Forming,China(No.201805D141005)Science and Technology Major Project of Shanxi Province,China(Nos.20191102008,20191102007,20181101008)Yantai High-end Talent Introduction“Double Hundred Plan”,China(2021)。
基金supported financially by the National Natural Science Foundation of China (No. 51401064)the Sci-tech Development Project in Shandong Province (No. 2014GGX10211)+1 种基金the Sci-tech Major Project in Shandong Province (No. 2015ZDJQ02002)the Fundamental Research Funds for the Central Universities (No. HIT.NSRIF.2016109)
文摘The rolling direction（RD） and the transverse direction（TD） samples were obtained from an as-rolled ZK60 magnesium alloy sheet with strong anisotropy of initial texture and their mechanical properties were tested at various deformation temperatures. Meanwhile, the microstructure and texture of these samples after fracture were investigated. Results revealed that a higher flow stress along the RD than that along the TD at room temperature were ascribed to the strong anisotropy of transitional texture, and this texture effect was remarkably weakened with the increase of deformation temperature. Deformation structure was dominant at 100℃, and was replaced by dynamic recrystallization structure when the deformation temperature increased to 200℃ and 300℃. The texture presented a strong texture（transitional texture in the RD sample and basal texture in the TD sample） at 100℃, but its intensity visibly decreased and texture components became more disperse at 200℃ and 300℃. These microstructure and texture results were employed in conjunction with calculated results to argue that raising deformation temperature could increase the activity of non-basal slip by tailoring the relative critical resolved shear stress of each deformation mode and finally result in low texture effect on mechanical anisotropy.
基金the National Key R&D Program of China(2017YFA0204403)National Natural Science Foundation of China(51601003,51901103)the Fundamental Research Funds for the Central Universities(30918011342).
文摘Due to the insufficient slip systems,Mg and its alloys exhibit poor ductility during plastic deformation at room temperature.To solve this problem,alloying is considered as a most effective method to improve the ductility of Mg alloys,which attracts wide attentions of industries.However,it is still a challenge to understand the ductilization mechanism,because of the complicated alloying elements and their interactions with Mg matrix.In this work,pure Mg and Mg-Y alloys were comparatively studied to investigate the effect of Y addition on microstructure evolution and mechanical properties.A huge increase of uniform elongation,from 5.3%to 20.7%,was achieved via only 3 wt%addition of yttrium.TEM results revealed that the only activated slip system in pure Mg was basalslip,led to its poor ductility at room temperature.In contrast,a large number of stacking faults and non-basal dislocations with<c>component were observed in the deformed Mg-Y alloy,which was proposed as the main reason for significant improvement of strain hardening and ductility.High resolution TEM indicated that most of the stacking faults were II and 12 intrinsic faults,which played a critical role in improving the ductility of Mg-Y alloy.Addition of Y into Mg alloy decreased the stacking fault energy,which induced high density stacking faults in the grain interior.
文摘Deformation behavior of 1 Al containing Mg alloy has been investigated in the present study.After annealing,the Mg-1 Al alloy shows a typical basal texture.When compared to the pure Mg having a similar texture and grain size,the Mg-1 Al alloy shows much higher strength and larger elongation.Slip trace analyses of the tensile strained specimens show that non-basal slips such as pyramidal I and II slips can be easily activated at an early stage of deformation in the Mg-1 Al alloy and the grains in the Mg-1 Al alloy are seen to accommodate a larger degree of deformation than those in the pure Mg at a given strain.With increasing tensile strain,however,there is a strain localization along the initially formed slip lines of non-basal slips,forming surface steps without activating multiple slip lines.
