Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle materials.This study demonstrates the susceptibility of non-magne...Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle materials.This study demonstrates the susceptibility of non-magnetic single-crystal calcium fluoride(CaF_(2))to the magneto-plastic effect.The influence of magneto-plasticity on CaF_(2) was confirmed in micro-deformation tests under a weak magnetic field of 20 mT.The surface pile-up effect was weakened by 10-15 nm along with an enlarged plastic zone and suppressed crack propagation under the influence of the magnetic field.Micro-cutting tests along different crystal orientations on the(111)plane of CaF_(2) revealed an increase in the ductile-brittle transition of the machined surface with the aid of magneto-plasticity where the largest increase in ductile-brittle transition occurred along the[112]orientation from 512 nm to a range of 664-806 nm.Meanwhile,the subsurface damage layer was concurrently thinner under magnetic influence.An anisotropic influence of the magnetic field relative to the single-crystal orientation and the cutting direction was also observed.An analytical model was derived to determine an orientation factor M that successfully describes the anisotropy while considering the single-crystal dislocation behaviour,material fracture toughness,and the orientation of the magnetic field.Previously suggested theoretical mechanism of magneto-plasticity via formation of non-singlet electronic states in defected configurations was confirmed with density functional theory calculations.The successful findings on the influence of a weak magnetic field on plasticity present an opportunity for the adoption of magnetic-assisted micro-cutting of non-magnetic materials.展开更多
The highly sensitive giant magneto-impedance effect in a solenoid containing a magnetic core of Fe36Co36Nb4Si4.sB19.2 (FeCo-based) ribbon under a weak magnetic field (WMF) is presented in this paper. The FeCo-base...The highly sensitive giant magneto-impedance effect in a solenoid containing a magnetic core of Fe36Co36Nb4Si4.sB19.2 (FeCo-based) ribbon under a weak magnetic field (WMF) is presented in this paper. The FeCo-based amorphous ribbon is prepared by single roller quenching and annealed with Joule heat in a flowing nitro- gen atmosphere. The giant magnetoimpedance effect in solenoid (GMIES) profiles are measured with an HP4294A impedance analyzer. The result shows that the CMIES responds to the WMF sensitively (as high as 1580 %/A.m-1). The high sensitivity can be obtained in a moderate narrow range of annealing current density (30-34 A/mm2) and closely depends on the driven current frequency. The highest sensitivity (1580 %/A.m-1) is obtained when the FeCo- based amorphous ribbon is annealed at 32 A/mm2 for 10 min and then driven with an alterning current (AC) at the frequency of 350 kHz. The highly sensitive GMIES under the WMF may result from the multiple magnetic-anisotropic structure, which is induced by the temperature gradient produced during Joule-heating the ribbon.展开更多
High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic fie...High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic field is a promising solution for improvement in the slag resistance of refractory.The wetting of alumina refractory ceramics with different basicities of high alumina slags under a weak static magnetic field was analyzed,given that a weak static magnetic field can affect the corrosion behavior of refractory ceramics.Taking slag S_(3) as an example,when there was an external static magnetic field of 1.0 mT at 1600 ℃,the thickness of calcium aluminate reaction layer at the interface decreased by 36.7%,the denting depth of interface decreased by 35.6%,and the apparent wetting angle increased by 20%.The living radicals and their formation path in oxide melts were verified by first-principles calculation combined with electron paramagnetic resonance spectroscopy analysis.The influence of the flux density of a weak static magnetic field on the wetting behavior of slags was also explored.The contact angle of the slags increased owing to the inhibitory effect of magnetic field on the radicalinvolved reaction at the interface of the slag and the alumina refractory ceramic.The relationships between the magnetic flux density,diffusion coefficient,slag microstructure(hyperfine coupling constant),and contact angle were established.This provides a theoretical basis for the field control of radical involved reactive wetting between inorganic oxide slags and solid oxide ceramics.展开更多
There must be electromagnetic fields created during high-energy heavy-ion collisions.Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma(QGP),compared to the energy scales o...There must be electromagnetic fields created during high-energy heavy-ion collisions.Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma(QGP),compared to the energy scales of the strong interaction,they are potentially important to some electromagnetic probes.In this work,we propose the coupled effect of the weak magnetic field and the longitudinal dynamics of the background medium for the first time.We demonstrate that the induced photon spectrum can be highly azimuthally anisotropic when the quarkgluon plasma is in the presence of a weak external magnetic field.On the other hand,the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate.After hydrodynamic evolution with a tilted fireball configuration,the experimentally measured direct photon elliptic flow is well reproduced.Meanwhile,the used time-averaged magnetic field in the hydrodynamic stage is found no larger than a few percent of the pion mass square.展开更多
基金supported by the Ministry of Education,Singapore,under its Academic Research Funds(Grant Nos.:MOE-T2EP50120-0010,MOE-T2EP50220-0010)the funding from the Ministère des Relations Internationales et de la Francophonie du Québec,Coopération Québec-Singapour,with which this work was partially supported。
文摘Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle materials.This study demonstrates the susceptibility of non-magnetic single-crystal calcium fluoride(CaF_(2))to the magneto-plastic effect.The influence of magneto-plasticity on CaF_(2) was confirmed in micro-deformation tests under a weak magnetic field of 20 mT.The surface pile-up effect was weakened by 10-15 nm along with an enlarged plastic zone and suppressed crack propagation under the influence of the magnetic field.Micro-cutting tests along different crystal orientations on the(111)plane of CaF_(2) revealed an increase in the ductile-brittle transition of the machined surface with the aid of magneto-plasticity where the largest increase in ductile-brittle transition occurred along the[112]orientation from 512 nm to a range of 664-806 nm.Meanwhile,the subsurface damage layer was concurrently thinner under magnetic influence.An anisotropic influence of the magnetic field relative to the single-crystal orientation and the cutting direction was also observed.An analytical model was derived to determine an orientation factor M that successfully describes the anisotropy while considering the single-crystal dislocation behaviour,material fracture toughness,and the orientation of the magnetic field.Previously suggested theoretical mechanism of magneto-plasticity via formation of non-singlet electronic states in defected configurations was confirmed with density functional theory calculations.The successful findings on the influence of a weak magnetic field on plasticity present an opportunity for the adoption of magnetic-assisted micro-cutting of non-magnetic materials.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 50871104 and 11079029)the Natural Science Foundation of Zhejiang Province,China (Grant Nos. Y4080324 and Y6110246)the Natural Science Foundation of Shanxi Province, China (Grant No. Sj08e101)
文摘The highly sensitive giant magneto-impedance effect in a solenoid containing a magnetic core of Fe36Co36Nb4Si4.sB19.2 (FeCo-based) ribbon under a weak magnetic field (WMF) is presented in this paper. The FeCo-based amorphous ribbon is prepared by single roller quenching and annealed with Joule heat in a flowing nitro- gen atmosphere. The giant magnetoimpedance effect in solenoid (GMIES) profiles are measured with an HP4294A impedance analyzer. The result shows that the CMIES responds to the WMF sensitively (as high as 1580 %/A.m-1). The high sensitivity can be obtained in a moderate narrow range of annealing current density (30-34 A/mm2) and closely depends on the driven current frequency. The highest sensitivity (1580 %/A.m-1) is obtained when the FeCo- based amorphous ribbon is annealed at 32 A/mm2 for 10 min and then driven with an alterning current (AC) at the frequency of 350 kHz. The highly sensitive GMIES under the WMF may result from the multiple magnetic-anisotropic structure, which is induced by the temperature gradient produced during Joule-heating the ribbon.
基金supported by the National Natural Science Foundation of China(52272022)Key Program of the Natural Science Foundation of Hubei Province of China(2021CFA071).
文摘High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic field is a promising solution for improvement in the slag resistance of refractory.The wetting of alumina refractory ceramics with different basicities of high alumina slags under a weak static magnetic field was analyzed,given that a weak static magnetic field can affect the corrosion behavior of refractory ceramics.Taking slag S_(3) as an example,when there was an external static magnetic field of 1.0 mT at 1600 ℃,the thickness of calcium aluminate reaction layer at the interface decreased by 36.7%,the denting depth of interface decreased by 35.6%,and the apparent wetting angle increased by 20%.The living radicals and their formation path in oxide melts were verified by first-principles calculation combined with electron paramagnetic resonance spectroscopy analysis.The influence of the flux density of a weak static magnetic field on the wetting behavior of slags was also explored.The contact angle of the slags increased owing to the inhibitory effect of magnetic field on the radicalinvolved reaction at the interface of the slag and the alumina refractory ceramic.The relationships between the magnetic flux density,diffusion coefficient,slag microstructure(hyperfine coupling constant),and contact angle were established.This provides a theoretical basis for the field control of radical involved reactive wetting between inorganic oxide slags and solid oxide ceramics.
文摘There must be electromagnetic fields created during high-energy heavy-ion collisions.Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma(QGP),compared to the energy scales of the strong interaction,they are potentially important to some electromagnetic probes.In this work,we propose the coupled effect of the weak magnetic field and the longitudinal dynamics of the background medium for the first time.We demonstrate that the induced photon spectrum can be highly azimuthally anisotropic when the quarkgluon plasma is in the presence of a weak external magnetic field.On the other hand,the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate.After hydrodynamic evolution with a tilted fireball configuration,the experimentally measured direct photon elliptic flow is well reproduced.Meanwhile,the used time-averaged magnetic field in the hydrodynamic stage is found no larger than a few percent of the pion mass square.