The high-throughput diffusion-multiple technique and thermodynamics databases were used to design new high-strength Ti alloys. The composition–microstructure–property relationships of the Ti64–xMo alloys were obtai...The high-throughput diffusion-multiple technique and thermodynamics databases were used to design new high-strength Ti alloys. The composition–microstructure–property relationships of the Ti64–xMo alloys were obtained. The phase fraction and composition of the α and β phases of the Ti64–xMo alloys were calculated using the Thermo-Calc software. After aging at 600℃, the Ti64–6 Mo alloy precipitated ultrafine α phases. This phenomenon was explained on the basis of the pseudo-spinodal mechanism by calculating the Gibbs energy curves of the α and β phases of the Ti64–xMo alloys at 600℃. Bulk forged Ti64–6 Mo alloy exhibited high strength and moderate plasticity after α/β-phase-field solution treatment plus aging. The tensile properties of the alloy were determined by the size and morphology of the primary and secondary α phases and by the β grain size.展开更多
Erratum to:International Journal of Minerals, Metallurgy and Materials Volume 26, Number 9, September 2019, Page 1151https://doi.org/10.1007/s12613-019-1854-1The original version of this article unfortunately containe...Erratum to:International Journal of Minerals, Metallurgy and Materials Volume 26, Number 9, September 2019, Page 1151https://doi.org/10.1007/s12613-019-1854-1The original version of this article unfortunately contained a mistake. The presentation of Fig. 11 was incorrect. The correct version is given below:展开更多
Traditional theoretical and empirical calculation methods can guide the design of β-and metastable β-alloys for bio-titanium. However, it is still difficult to obtain novel near-β-Ti alloys with low modulus. This s...Traditional theoretical and empirical calculation methods can guide the design of β-and metastable β-alloys for bio-titanium. However, it is still difficult to obtain novel near-β-Ti alloys with low modulus. This study developed a method that combines machine learning with calculation of phase diagrams(CALPHAD) to facilitate the design of near-β-Ti alloys. An elastic modulus database of Ti–Nb–Zr–Mo–Ta–Sn system was constructed first, and then three features(the electron to atom ratio, mean absolute deviation of atom mass, and mean electronegativity) were selected as the key factors of modulus by performing a three-step feature selection. With these features, a highly accurate model was built for predicting the modulus of near-β-Ti alloys. To further ensure the accuracy of modulus prediction, machine learning with the elastic constants calculated was leveraged by CALPHAD database. The root mean square error of the well-trained model can be as low as 6.75 GPa. Guided by the prediction of machine learning and CALPHAD, three novel near-β-Ti alloys with elastic modulus below 50 GPa were successfully designed in this study. The best candidate alloy(Ti–26Nb–4Zr–4Sn–1Mo–Ta) exhibits an ultra-low modulus(36.6 GPa) after cold rolling with a thickness reduction of 20%. Our method can greatly save time and resources in the development of novel Ti alloys, and experimental verifications have demonstrated the reliability of this method.展开更多
The design and fabrication of conductive hydrogels with high stretchability,compressibility,self-healing properties and good adhesion remains a significant challenge.We have fabricated composite hydrogels by random po...The design and fabrication of conductive hydrogels with high stretchability,compressibility,self-healing properties and good adhesion remains a significant challenge.We have fabricated composite hydrogels by random polymerization of acrylic acid(AA)and dopamine(DA)in the presence of multi-walled carbon nanotubes(MWCNTs).The π-π interaction between DA and MWCNTs makes MWCNTs stably and homogenously dispersed in water.The fabricated PAA-PDA/CNT composite hydrogels possess relatively high mechanical strength(maximum Youngzs modulus:800 kPa)and can be stretched to 1280%strain and compressed to 80%strain.The multiple hydrogen bonding formed between functional groups of PAA-PDA and MWCNTs can effectively dissipate energy and quickly achieve self-healing.The composite hydrogels also show good adhesion and can easily adhere to various inorganic or organic surfaces.In addition,the hydrogel reveals stable strain sensitivity and can be used as skin sensors.展开更多
The main reason for the high strength in near-βtitanium alloys is the ultrafine precipitation of the acicular secondary a phase in theβmatrix.The purpose of this study is to use the pseudo-spinodal mechanism to obta...The main reason for the high strength in near-βtitanium alloys is the ultrafine precipitation of the acicular secondary a phase in theβmatrix.The purpose of this study is to use the pseudo-spinodal mechanism to obtain the ultrafine a phase for the design of a new high-strength near-γtitanium alloy.Thermodynamic calculations and TC21-(TC21+15 Mo)diffusion couple composition gradient experiments were used to demonstrate that TC21+3 Mo alloy can undergo a pseudo-spinodal decomposition to obtain the ultrafine a phase,resulting in a high-strength alloy.By adjusting the heat treatment process to obtain a bimodal microstructure,the alloy exhibits a good balance between ultimate tensile strength(1351 MPa)and plasticity(8.5%strain).Thus,it was demonstrated that the pseudospinodal mechanism combined with a high-throughput diffusion couple technique is an effective method for designing high-strength titanium alloys.展开更多
In this paper,we consider a singularly perturbed convection-diffusion prob-lem.The problem involves two small parameters that gives rise to two boundary lay-ers at two endpoints of the domain.For this problem,a non-mo...In this paper,we consider a singularly perturbed convection-diffusion prob-lem.The problem involves two small parameters that gives rise to two boundary lay-ers at two endpoints of the domain.For this problem,a non-monotonefinite element methods is used.A priori error bound in the maximum norm is obtained.Based on the a priori error bound,we show that there exists Bakhvalov-type mesh that gives optimal error bound of O(N-2)which is robust with respect to the two perturbation parameters.Numerical results are given that confirm the theoretical result.展开更多
基金Projects(2016YFB0701301,2018YFB0704100)supported by the National Key Technologies R&D Program of ChinaProjects(51901251,51671218,51501229)supported by the National Natural Science Foundation of ChinaProject(2020JJ5750)supported by the Natural Science Foundation of Hunan Province,China。
基金Project(2014CB644000)supported by the National Basic Research Program of ChinaProject(2016YFB0701301)supported by the National Key Technology R&D Program of China+1 种基金Projects(51371200,51671218)supported by the National Natural Science Foundation of ChinaProject supported by State Key Laboratory of Powder Metallurgy,Central South University,China
基金financial support from the National Key Technologies R&D Program of China (Grant No. 2016YFB0701301 and 2018YFB0704100)National Natural Science Foundation of China (Grant No. 51671218 and 51501229)+1 种基金National Key Basic Research Program of China (973 Program) (Grant No. 2014CB644000)State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China
文摘The high-throughput diffusion-multiple technique and thermodynamics databases were used to design new high-strength Ti alloys. The composition–microstructure–property relationships of the Ti64–xMo alloys were obtained. The phase fraction and composition of the α and β phases of the Ti64–xMo alloys were calculated using the Thermo-Calc software. After aging at 600℃, the Ti64–6 Mo alloy precipitated ultrafine α phases. This phenomenon was explained on the basis of the pseudo-spinodal mechanism by calculating the Gibbs energy curves of the α and β phases of the Ti64–xMo alloys at 600℃. Bulk forged Ti64–6 Mo alloy exhibited high strength and moderate plasticity after α/β-phase-field solution treatment plus aging. The tensile properties of the alloy were determined by the size and morphology of the primary and secondary α phases and by the β grain size.
文摘Erratum to:International Journal of Minerals, Metallurgy and Materials Volume 26, Number 9, September 2019, Page 1151https://doi.org/10.1007/s12613-019-1854-1The original version of this article unfortunately contained a mistake. The presentation of Fig. 11 was incorrect. The correct version is given below:
基金Supported by the Natural Science Foundation of Shanxi （2013021029-2）, the 12th Five-Year Science and Technology Support Program （2012BAB 13B04）, the Research Fund for the Doctoral Program of Higher Education of China （20111402120004）
基金financially supported by the National Natural Science Foundation of China (No.52071339)the Natural Science Foundation of Hunan Province,China (No.2020JJ4739)Guangxi Key Laboratory of Information Materials(Guilin University of Electronic Technology),China (No.201009-K)。
文摘Traditional theoretical and empirical calculation methods can guide the design of β-and metastable β-alloys for bio-titanium. However, it is still difficult to obtain novel near-β-Ti alloys with low modulus. This study developed a method that combines machine learning with calculation of phase diagrams(CALPHAD) to facilitate the design of near-β-Ti alloys. An elastic modulus database of Ti–Nb–Zr–Mo–Ta–Sn system was constructed first, and then three features(the electron to atom ratio, mean absolute deviation of atom mass, and mean electronegativity) were selected as the key factors of modulus by performing a three-step feature selection. With these features, a highly accurate model was built for predicting the modulus of near-β-Ti alloys. To further ensure the accuracy of modulus prediction, machine learning with the elastic constants calculated was leveraged by CALPHAD database. The root mean square error of the well-trained model can be as low as 6.75 GPa. Guided by the prediction of machine learning and CALPHAD, three novel near-β-Ti alloys with elastic modulus below 50 GPa were successfully designed in this study. The best candidate alloy(Ti–26Nb–4Zr–4Sn–1Mo–Ta) exhibits an ultra-low modulus(36.6 GPa) after cold rolling with a thickness reduction of 20%. Our method can greatly save time and resources in the development of novel Ti alloys, and experimental verifications have demonstrated the reliability of this method.
基金the Introduction and Cultivation Plan of Young Innovative Talents in Colleges and Universities of Shandong Province,the Shandong Key R&D Program(No.2019GSF109050)Research Leader Foundation of"20 Policies of Colleges and Universities"of Jinan City(No.2018GXRC027)the National Natural Science Foundation of China(No.31670590).
文摘The design and fabrication of conductive hydrogels with high stretchability,compressibility,self-healing properties and good adhesion remains a significant challenge.We have fabricated composite hydrogels by random polymerization of acrylic acid(AA)and dopamine(DA)in the presence of multi-walled carbon nanotubes(MWCNTs).The π-π interaction between DA and MWCNTs makes MWCNTs stably and homogenously dispersed in water.The fabricated PAA-PDA/CNT composite hydrogels possess relatively high mechanical strength(maximum Youngzs modulus:800 kPa)and can be stretched to 1280%strain and compressed to 80%strain.The multiple hydrogen bonding formed between functional groups of PAA-PDA and MWCNTs can effectively dissipate energy and quickly achieve self-healing.The composite hydrogels also show good adhesion and can easily adhere to various inorganic or organic surfaces.In addition,the hydrogel reveals stable strain sensitivity and can be used as skin sensors.
基金financially supported by the National Key Technologies R&D Program of China(No.2016YFB0701301)the National Natural Science Foundation of China(Nos.51901251,51671218 and 51501229)the State Key Laboratory of Powder Metallurgy Independent Project of China(No.621021907)。
文摘The main reason for the high strength in near-βtitanium alloys is the ultrafine precipitation of the acicular secondary a phase in theβmatrix.The purpose of this study is to use the pseudo-spinodal mechanism to obtain the ultrafine a phase for the design of a new high-strength near-γtitanium alloy.Thermodynamic calculations and TC21-(TC21+15 Mo)diffusion couple composition gradient experiments were used to demonstrate that TC21+3 Mo alloy can undergo a pseudo-spinodal decomposition to obtain the ultrafine a phase,resulting in a high-strength alloy.By adjusting the heat treatment process to obtain a bimodal microstructure,the alloy exhibits a good balance between ultimate tensile strength(1351 MPa)and plasticity(8.5%strain).Thus,it was demonstrated that the pseudospinodal mechanism combined with a high-throughput diffusion couple technique is an effective method for designing high-strength titanium alloys.
基金the National Basic Research Program of China(2016YFC0502304,2018YFC0507203,2016YFC0502101)the National Science Foundation of China(31870462)and the Natural Science Foundation of Zhejiang Province(LQ20C030003).
基金This work is supported by National Science Foundation of China(91430104,11271145,11301044)Specialized Research Fund for the Doctoral Programof Higher Education(20114407110009)the key projects of Excellent young talents fund in universities of Anhui province(2013SQRL095ZD).
文摘In this paper,we consider a singularly perturbed convection-diffusion prob-lem.The problem involves two small parameters that gives rise to two boundary lay-ers at two endpoints of the domain.For this problem,a non-monotonefinite element methods is used.A priori error bound in the maximum norm is obtained.Based on the a priori error bound,we show that there exists Bakhvalov-type mesh that gives optimal error bound of O(N-2)which is robust with respect to the two perturbation parameters.Numerical results are given that confirm the theoretical result.
