The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature.To address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)all...The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature.To address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)alloy was developed using the unique role of rare earth and Ca solute atoms.In addition,the influence of the annealing process on the grain size,second phase,texture,and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity mag-nesium alloy sheets and obtaining optimal thermal-mechanical treatment parameters.The results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content:there are small amounts of larger-sized block and long string phases along the rolling direction(RD),as well as several spherical and rodlike particle phases inside the grains.With increas-ing annealing temperature,the grain size decreases and then increases,and the morphology,number,and size of the second phase also change correspondingly.The particle phase within the grains vanishes at 450℃,and the grain size increases sharply.In the full recrystal-lization stage at 300-350℃,the optimum strength-plasticity comprehensive mechanical properties are presented,with yield strengths of 182.1 and 176.9 MPa,tensile strengths of 271.1 and 275.8 MPa in the RD and transverse direction(TD),and elongation values of 27.4%and 32.3%,respectively.Moreover,there are still some larger-sized phases in the alloy that influence its mechanical properties,which offers room for improvement.展开更多
3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled an...3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled and annealed composites were systematically studied.The rolled composites exhibited a heterogeneous microstructure,consisting of deformed grains elongated along rolling direction(RD)and Y_(2)O_(3)particles bands distributed along RD.After annealing,static recrystallization(SRX)occurred and most deformed grains transformed into equiaxed grains.A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR,indicating that rolling path had great influences on texture of the composites.After annealing process,R-texture component disappeared or weakened,as results,a non-basal texture with double peaks tilting from normal direction(ND)to transverse direction(TD)and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites,respectively.The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR.Some Y_(2)O_(3)particles broke during rolling.The fracture of the composites was attributed to the existence of Y_(2)O_(3)clusters and interfacial debonding between particles and matrix during tension,as a result,the ductility was not as superior as matrix alloy.展开更多
The classification of infrasound events has considerable importance in improving the capability to identify the types of natural disasters.The traditional infrasound classification mainly relies on machine learning al...The classification of infrasound events has considerable importance in improving the capability to identify the types of natural disasters.The traditional infrasound classification mainly relies on machine learning algorithms after artificial feature extraction.However,guaranteeing the effectiveness of the extracted features is difficult.The current trend focuses on using a convolution neural network to automatically extract features for classification.This method can be used to extract signal spatial features automatically through a convolution kernel;however,infrasound signals contain not only spatial information but also temporal information when used as a time series.These extracted temporal features are also crucial.If only a convolution neural network is used,then the time dependence of the infrasound sequence will be missed.Using long short-term memory networks can compensate for the missing time-series features but induces spatial feature information loss of the infrasound signal.A multiscale squeeze excitation–convolution neural network–bidirectional long short-term memory network infrasound event classification fusion model is proposed in this study to address these problems.This model automatically extracted temporal and spatial features,adaptively selected features,and also realized the fusion of the two types of features.Experimental results showed that the classification accuracy of the model was more than 98%,thus verifying the effectiveness and superiority of the proposed model.展开更多
The unidirectional rolled Mg-Zn-Gd sheet usually exhibited non-basal texture with two peaks whose tilting angle were about 42°from normal direction to transverse direction(TD),which would cause the mechanical ani...The unidirectional rolled Mg-Zn-Gd sheet usually exhibited non-basal texture with two peaks whose tilting angle were about 42°from normal direction to transverse direction(TD),which would cause the mechanical anisotropy.In this study,multi-cross rolling followed by annealing was used to tailor the texture and mechanical anisotropy for Mg-Zn-Gd alloy.With increasing annealing temperature,the rolled basal texture with two peaks gradually transformed into the circle texture with multi-peaks.In order to figure out different texture components evolution during annealing,the basal texture,R-texture and T-texture component were defined and studied.The results showed that the change of R-texture and T-texture component was asynchronous with increasing annealing temperature from 250 to 400℃.The tilting angle of R-texture component increased slightly,while the tilting angle of T-texture component increased obviously,and this phenomenon was attributed to the preferential nucleation at grain nucleation stage rather than preferential grain growth.The yield strength along TD was more sensitive to annealing temperature compared with that along rolling direction(RD),resulting in different descending slopes and yield strength anisotropy with increasing annealing temperature.Annealing at 300℃was the best annealing temperature due to low yield strength anisotropy,moderate strength and good elongation among these annealing temperatures.The Schmid factor for basal slip indicated that the activity of basal slip along RD increased slightly,while that along TD increased obviously with increasing annealing temperature from 250 to 400℃,which should be caused by the asynchronous change of R-texture component and T-texture component,consequently resulting in the transformation from isotropic yield strength to anisotropic yield strength.展开更多
Spinal cord injury(SCI)often results in irreversible loss of sensory and motor functions,and most SCIs are incurable with current medical practice.One of the hardest challenges in treating SCI is the development of a ...Spinal cord injury(SCI)often results in irreversible loss of sensory and motor functions,and most SCIs are incurable with current medical practice.One of the hardest challenges in treating SCI is the development of a dysfunctional pathological microenvironment,which mainly comprises excessive inflammation,deposition of inhibitory molecules,neurotrophic factor deprivation,glial scar formation,and imbalance of vascular function.To overcome this challenge,implantation of functional biomaterials at the injury site has been regarded as a potential treatment for modulating the dysfunctional microenvironment to support axon regeneration,remyelination at injury site,and functional recovery after SCI.This review summarizes characteristics of dysfunctional pathological microenvironment and recent advances in biomaterials as well as the technologies used to modulate inflammatory microenvironment,regulate inhibitory microenvironment,and reshape revascularization microenvironment.Moreover,technological limitations,challenges,and future prospects of functional biomaterials to promote efficient repair of SCI are also discussed.This review will aid further understanding and development of functional biomaterials to regulate pathological SCI microenvironment.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52271107 and 52205392)the Natural Science Foundation of Shandong Province(No.ZR2021ME241)the Bintech-IMR R&D Program(No.GYY-JSBU-2022-012).
文摘The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature.To address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)alloy was developed using the unique role of rare earth and Ca solute atoms.In addition,the influence of the annealing process on the grain size,second phase,texture,and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity mag-nesium alloy sheets and obtaining optimal thermal-mechanical treatment parameters.The results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content:there are small amounts of larger-sized block and long string phases along the rolling direction(RD),as well as several spherical and rodlike particle phases inside the grains.With increas-ing annealing temperature,the grain size decreases and then increases,and the morphology,number,and size of the second phase also change correspondingly.The particle phase within the grains vanishes at 450℃,and the grain size increases sharply.In the full recrystal-lization stage at 300-350℃,the optimum strength-plasticity comprehensive mechanical properties are presented,with yield strengths of 182.1 and 176.9 MPa,tensile strengths of 271.1 and 275.8 MPa in the RD and transverse direction(TD),and elongation values of 27.4%and 32.3%,respectively.Moreover,there are still some larger-sized phases in the alloy that influence its mechanical properties,which offers room for improvement.
基金financial supports from the Natural Science Foundation of Shandong Province(ZR2021ME241)the Natural Science Foundation of Liaoning Province(No.2020-MS-004)+2 种基金the National Natural Science Foundation of China(NSFC,Nos.51601193 and 51701218)State Key Program of National Natural Science of China(No.51531002)National Key Research and Development Program of China(No.2016YFB0301104).
文摘3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled and annealed composites were systematically studied.The rolled composites exhibited a heterogeneous microstructure,consisting of deformed grains elongated along rolling direction(RD)and Y_(2)O_(3)particles bands distributed along RD.After annealing,static recrystallization(SRX)occurred and most deformed grains transformed into equiaxed grains.A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR,indicating that rolling path had great influences on texture of the composites.After annealing process,R-texture component disappeared or weakened,as results,a non-basal texture with double peaks tilting from normal direction(ND)to transverse direction(TD)and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites,respectively.The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR.Some Y_(2)O_(3)particles broke during rolling.The fracture of the composites was attributed to the existence of Y_(2)O_(3)clusters and interfacial debonding between particles and matrix during tension,as a result,the ductility was not as superior as matrix alloy.
基金supported by the Shaanxi Province Natural Science Basic Research Plan Project(2023-JC-YB-244).
文摘The classification of infrasound events has considerable importance in improving the capability to identify the types of natural disasters.The traditional infrasound classification mainly relies on machine learning algorithms after artificial feature extraction.However,guaranteeing the effectiveness of the extracted features is difficult.The current trend focuses on using a convolution neural network to automatically extract features for classification.This method can be used to extract signal spatial features automatically through a convolution kernel;however,infrasound signals contain not only spatial information but also temporal information when used as a time series.These extracted temporal features are also crucial.If only a convolution neural network is used,then the time dependence of the infrasound sequence will be missed.Using long short-term memory networks can compensate for the missing time-series features but induces spatial feature information loss of the infrasound signal.A multiscale squeeze excitation–convolution neural network–bidirectional long short-term memory network infrasound event classification fusion model is proposed in this study to address these problems.This model automatically extracted temporal and spatial features,adaptively selected features,and also realized the fusion of the two types of features.Experimental results showed that the classification accuracy of the model was more than 98%,thus verifying the effectiveness and superiority of the proposed model.
基金supported by the National Natural Science Foundation of China(No.52271107)Bintech-IMR R&D Program(GYY-JSBU-2022-012)+1 种基金the Natural Science Foundation of Shandong(ZR2021ME241)the Natural Science Foundation of Liaoning Province(No.2020-MS-004).
文摘The unidirectional rolled Mg-Zn-Gd sheet usually exhibited non-basal texture with two peaks whose tilting angle were about 42°from normal direction to transverse direction(TD),which would cause the mechanical anisotropy.In this study,multi-cross rolling followed by annealing was used to tailor the texture and mechanical anisotropy for Mg-Zn-Gd alloy.With increasing annealing temperature,the rolled basal texture with two peaks gradually transformed into the circle texture with multi-peaks.In order to figure out different texture components evolution during annealing,the basal texture,R-texture and T-texture component were defined and studied.The results showed that the change of R-texture and T-texture component was asynchronous with increasing annealing temperature from 250 to 400℃.The tilting angle of R-texture component increased slightly,while the tilting angle of T-texture component increased obviously,and this phenomenon was attributed to the preferential nucleation at grain nucleation stage rather than preferential grain growth.The yield strength along TD was more sensitive to annealing temperature compared with that along rolling direction(RD),resulting in different descending slopes and yield strength anisotropy with increasing annealing temperature.Annealing at 300℃was the best annealing temperature due to low yield strength anisotropy,moderate strength and good elongation among these annealing temperatures.The Schmid factor for basal slip indicated that the activity of basal slip along RD increased slightly,while that along TD increased obviously with increasing annealing temperature from 250 to 400℃,which should be caused by the asynchronous change of R-texture component and T-texture component,consequently resulting in the transformation from isotropic yield strength to anisotropic yield strength.
基金supported by the National Key R&D Program of China(Grant No.2022YFB3808000/2022YFB3808001)the National Natural Science Foundation of China(Grant Nos.82301554,51903050 and 82104888)+1 种基金Scientific Research Foundation for the High-level Talents Fujian University of Traditional Chinese Medicine(X2021007talents,X2019011talents)School management project of Fujian University of traditional Chinese Medicine(X2023019).
文摘Spinal cord injury(SCI)often results in irreversible loss of sensory and motor functions,and most SCIs are incurable with current medical practice.One of the hardest challenges in treating SCI is the development of a dysfunctional pathological microenvironment,which mainly comprises excessive inflammation,deposition of inhibitory molecules,neurotrophic factor deprivation,glial scar formation,and imbalance of vascular function.To overcome this challenge,implantation of functional biomaterials at the injury site has been regarded as a potential treatment for modulating the dysfunctional microenvironment to support axon regeneration,remyelination at injury site,and functional recovery after SCI.This review summarizes characteristics of dysfunctional pathological microenvironment and recent advances in biomaterials as well as the technologies used to modulate inflammatory microenvironment,regulate inhibitory microenvironment,and reshape revascularization microenvironment.Moreover,technological limitations,challenges,and future prospects of functional biomaterials to promote efficient repair of SCI are also discussed.This review will aid further understanding and development of functional biomaterials to regulate pathological SCI microenvironment.
