Tungsten as a material exhibits broad and increasingly important applications;however,the characterization of its ductile-to-brittle transition(BDT)is currently limited to large-scale scenarios and destructive testing...Tungsten as a material exhibits broad and increasingly important applications;however,the characterization of its ductile-to-brittle transition(BDT)is currently limited to large-scale scenarios and destructive testing.In this study,we overcome this challenge by implementing small-scale techniques to provide a comprehensive understanding of the BDT behavior of pure tungsten.In order to predict the failure mode at various temperature ranges,the practical fracture analysis diagram has been proposed to describe the resistance to shear flow and cracking behavior with temperature.High temperature nano-indentation tests have provided the inherent mechanical responses corresponding to the maximum shear stress at various temperatures,which is required for dislocation activities in an atomic scaled activation volume.On one hand,atomistic simulations have provided the temperature dependence of brittle fracture stress,where the atomic bonds break due to intergranular or intragranular fracture.We considered four tungsten specimens having various microstructures prepared using different processing conditions of cold-rolling and post-annealing,and their BDT ranges were inferred using the obtained fracture analysis diagram with the statistical data processing.The fracture analysis diagram of each specimen obtained were compared with the direct observation of fracture responses in macroscopic mechanical tests,which conclusively indicated that the small-scale inherent mechanical properties are greatly relevant to the macroscopic BDT behavior in pure tungsten.Based on the BDT estimations by small-scale characterization,we provided further insights into the factors affecting the BDT behavior of tungsten,focusing on the contributions of different types of dislocations.展开更多
In this work,the thermodynamic,mechanical properties and electronic behaviors of D022-TiAl3 doped with W and 15 groupⅣM(M=C,Ge,Pb,Si and Sn)dopants are investigated by DFT methods.We established that ductility can be...In this work,the thermodynamic,mechanical properties and electronic behaviors of D022-TiAl3 doped with W and 15 groupⅣM(M=C,Ge,Pb,Si and Sn)dopants are investigated by DFT methods.We established that ductility can be improved using multi-doping approach and revealed the mechanisms behind such brittle-to-ductile transition.In addition,it is found that there is linearity between changes in Young’s modulus and tensile/compre s sive strain ratio.An alternate insight into brittle-to-ductile transition during ductile mode cutting of brittle materials is proposed.展开更多
In recent years,transition metal silicides have become the potential high temperature materials.The ternary silicide has attracted the attention of scientists and researchers.But their inherent brittle behaviors hinde...In recent years,transition metal silicides have become the potential high temperature materials.The ternary silicide has attracted the attention of scientists and researchers.But their inherent brittle behaviors hinder their wide applications.In this work,we use the first-principles method to design four vacancy defects and discuss the effects of vacancy defects on the structural stability,mechanical properties,electronic and thermodynamic properties of hexagonal Cr;BSi;silicide.The data of lattice vibration and thermodynamic parameters indicate that the Cr;BSi;with different atomic vacancies can possess the structural stabilities.The different atomic vacancies change the mechanical properties and induce the Cr;BSi;to implement the brittle-to-ductile transition.The shear deformation resistance and volume deformation resistance of Cr;BSi;are weakened by different vacancy defects.But the brittleness behavior is remarkably improved.The structural stability and brittle-to-ductile transition of Cr;BSi;with different vacancies are explored by the electronic structures.Moreover,the thermal parameters indicate that the Cr;BSi;with vacancies exhibit different thermodynamic properties with temperature rising.展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Ministry of Science,ICT(MSIT)[NRF-2020R1A5A6017701,NRF-2019M3D1A1079214,and NRF-2020R1A6A3A13076748]the ITER Technology R&D Programme。
文摘Tungsten as a material exhibits broad and increasingly important applications;however,the characterization of its ductile-to-brittle transition(BDT)is currently limited to large-scale scenarios and destructive testing.In this study,we overcome this challenge by implementing small-scale techniques to provide a comprehensive understanding of the BDT behavior of pure tungsten.In order to predict the failure mode at various temperature ranges,the practical fracture analysis diagram has been proposed to describe the resistance to shear flow and cracking behavior with temperature.High temperature nano-indentation tests have provided the inherent mechanical responses corresponding to the maximum shear stress at various temperatures,which is required for dislocation activities in an atomic scaled activation volume.On one hand,atomistic simulations have provided the temperature dependence of brittle fracture stress,where the atomic bonds break due to intergranular or intragranular fracture.We considered four tungsten specimens having various microstructures prepared using different processing conditions of cold-rolling and post-annealing,and their BDT ranges were inferred using the obtained fracture analysis diagram with the statistical data processing.The fracture analysis diagram of each specimen obtained were compared with the direct observation of fracture responses in macroscopic mechanical tests,which conclusively indicated that the small-scale inherent mechanical properties are greatly relevant to the macroscopic BDT behavior in pure tungsten.Based on the BDT estimations by small-scale characterization,we provided further insights into the factors affecting the BDT behavior of tungsten,focusing on the contributions of different types of dislocations.
基金partially supported by the National Research Foundation,Prime Minister’s Office,Singapore under its Marine Science Research and Development program(Award No.MSRDPP28)the Ministry of Education,Singapore under Tier 2 program(Award No.MOE2018-T2-1-163)。
文摘In this work,the thermodynamic,mechanical properties and electronic behaviors of D022-TiAl3 doped with W and 15 groupⅣM(M=C,Ge,Pb,Si and Sn)dopants are investigated by DFT methods.We established that ductility can be improved using multi-doping approach and revealed the mechanisms behind such brittle-to-ductile transition.In addition,it is found that there is linearity between changes in Young’s modulus and tensile/compre s sive strain ratio.An alternate insight into brittle-to-ductile transition during ductile mode cutting of brittle materials is proposed.
基金supported by the Natural Science Foundation of Liaoning Province,China(Grant No.2019JH/30100019)。
文摘In recent years,transition metal silicides have become the potential high temperature materials.The ternary silicide has attracted the attention of scientists and researchers.But their inherent brittle behaviors hinder their wide applications.In this work,we use the first-principles method to design four vacancy defects and discuss the effects of vacancy defects on the structural stability,mechanical properties,electronic and thermodynamic properties of hexagonal Cr;BSi;silicide.The data of lattice vibration and thermodynamic parameters indicate that the Cr;BSi;with different atomic vacancies can possess the structural stabilities.The different atomic vacancies change the mechanical properties and induce the Cr;BSi;to implement the brittle-to-ductile transition.The shear deformation resistance and volume deformation resistance of Cr;BSi;are weakened by different vacancy defects.But the brittleness behavior is remarkably improved.The structural stability and brittle-to-ductile transition of Cr;BSi;with different vacancies are explored by the electronic structures.Moreover,the thermal parameters indicate that the Cr;BSi;with vacancies exhibit different thermodynamic properties with temperature rising.
基金supported by the National Natural Science Foundation of China(51671168 and 51871197)the National Key Research and Development Program of China(2017YFA0208200)the National 111 Project(B16042).
