The elastic, magnetoelastic, and phonon properties of Ni2FeGa were investigated through first-principles calculations. The obtained elastic and phonon dispersion curves for the austenite and martensite phases agree we...The elastic, magnetoelastic, and phonon properties of Ni2FeGa were investigated through first-principles calculations. The obtained elastic and phonon dispersion curves for the austenite and martensite phases agree well with available the- oretical and experimental results. The isotropic elastic moduli are also predicted along with the polycrystalline aggregate properties including the bulk modulus, shear modulus, Young＇s modulus, and Poisson＇s ratio. The Pugh ratio indicates that Ni2FeGa shows ductility, especially the austenite phase, which is consistent with the experimental results. The Debye tem- peratures of the Ni2FeGa in the austenite and martensite phases are 344 K and 392 K, respectively. It is predicted that the magnetoelastic coefficient is -5.3 x 10^6 J/m3 and magnetostriction coefficient is between 135 and 55 ppm in the Ni2FeGa austenite phase.展开更多
Magnetic field annealing(MFA) was used to tailor the magnetostriction and magnetic domains of Fe80Ga16Al4 alloy,and the relationship between the two characteristics was studied.The <100>-oriented alloy was prepa...Magnetic field annealing(MFA) was used to tailor the magnetostriction and magnetic domains of Fe80Ga16Al4 alloy,and the relationship between the two characteristics was studied.The <100>-oriented alloy was prepared by the directional solidification technique and annealed for 20 min at 700℃ in a magnetic field of 250 mT along a direction 45 ° to the <100> orientation,followed by furnace cooling in the same magnetic field.The magnetostriction along the length direction(λ‖),the width direction(λ丄) and the saturation magnetostriction(λs) was changed from λ‖=208 × 10^(-6) and λ丄=-16 × 10^(-6) of the initial alloy to λ‖≈λ丄≈ 1/2 λs ≈ 112 × 10^(-6)after MFA.The magnetic domain structure,which mainly refers to the number,size,and direction of the domains,was tailored and rearranged by MFA.This rearrangement of the magnetic domain structure resulted in a shift of magnetostrictive properties parallel and perpendicular to the <100> orientation for the Fe80Ga16A14 alloy.This magnetic field annealing method can aid understanding of the relationship between the microscopic magnetic domains and the macroscopic magnetostrictive properties.It can also aid in further tailoring better magnetostrictive properties within magnetostrictive materials to meet the requirements of different application conditions.展开更多
The microstructure,orientation and magnetostrictive properties of a Fe_(81)Ga_(19)poly crystal grown by Bridgman method were investigated.A big central single crystal surrounded by some small crystals was observed.Lan...The microstructure,orientation and magnetostrictive properties of a Fe_(81)Ga_(19)poly crystal grown by Bridgman method were investigated.A big central single crystal surrounded by some small crystals was observed.Lane X-ray back-reflection confirmed the<001>orientation of the central crystal and deviation from the<001>direction for the edge crystals.Subgrain boundaries were monitored in the crystal.It was confirmed that orientations of all the subgrains were very close to the<001>direction.Measurement of the magnetostriction in different crystals indicated the strong anisotropy of the magnetostrictive properties.This work opens the possibility of preparing large-sized single crystal of FeGa alloys by using the Bridgman method.展开更多
<100>-,<112>-and <149>-oriented single crystals of Fe_(75.5)Ga_(24.5) alloy were prepared by optical float zone melting method.The pseudoelasticity behavior and elastocaloric effect of the single cry...<100>-,<112>-and <149>-oriented single crystals of Fe_(75.5)Ga_(24.5) alloy were prepared by optical float zone melting method.The pseudoelasticity behavior and elastocaloric effect of the single crystals were investigated,as well as the associate microstructures.D0_(3) phase structure was realized by solution treatment at 800 0C and annealed at 600℃ for 10 h.The compressive deformation behavior exhibits significant dependence on the crystalline directions.Excellent pseudoelasticity with recoverable strain up to 5% is obtained by compression along <149>direction.The pseudoelasticity disappears after five deformation cycles.Adiabatic temperature change is simultaneously detected during the pseudoelasticity,especially during loading process.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174030 and 11504020)the Fundamental Research Funds for the Central Universities of China(Grant No.FRF-TP-16-064A1,06500031)
文摘The elastic, magnetoelastic, and phonon properties of Ni2FeGa were investigated through first-principles calculations. The obtained elastic and phonon dispersion curves for the austenite and martensite phases agree well with available the- oretical and experimental results. The isotropic elastic moduli are also predicted along with the polycrystalline aggregate properties including the bulk modulus, shear modulus, Young＇s modulus, and Poisson＇s ratio. The Pugh ratio indicates that Ni2FeGa shows ductility, especially the austenite phase, which is consistent with the experimental results. The Debye tem- peratures of the Ni2FeGa in the austenite and martensite phases are 344 K and 392 K, respectively. It is predicted that the magnetoelastic coefficient is -5.3 x 10^6 J/m3 and magnetostriction coefficient is between 135 and 55 ppm in the Ni2FeGa austenite phase.
基金financially supported by Beijing Science and Technology Planning Project(No.Z20110000672003)。
文摘Magnetic field annealing(MFA) was used to tailor the magnetostriction and magnetic domains of Fe80Ga16Al4 alloy,and the relationship between the two characteristics was studied.The <100>-oriented alloy was prepared by the directional solidification technique and annealed for 20 min at 700℃ in a magnetic field of 250 mT along a direction 45 ° to the <100> orientation,followed by furnace cooling in the same magnetic field.The magnetostriction along the length direction(λ‖),the width direction(λ丄) and the saturation magnetostriction(λs) was changed from λ‖=208 × 10^(-6) and λ丄=-16 × 10^(-6) of the initial alloy to λ‖≈λ丄≈ 1/2 λs ≈ 112 × 10^(-6)after MFA.The magnetic domain structure,which mainly refers to the number,size,and direction of the domains,was tailored and rearranged by MFA.This rearrangement of the magnetic domain structure resulted in a shift of magnetostrictive properties parallel and perpendicular to the <100> orientation for the Fe80Ga16A14 alloy.This magnetic field annealing method can aid understanding of the relationship between the microscopic magnetic domains and the macroscopic magnetostrictive properties.It can also aid in further tailoring better magnetostrictive properties within magnetostrictive materials to meet the requirements of different application conditions.
基金financially supported by the National Natural Science Foundations of China (Nos.51331001 and 51520105002)。
文摘The microstructure,orientation and magnetostrictive properties of a Fe_(81)Ga_(19)poly crystal grown by Bridgman method were investigated.A big central single crystal surrounded by some small crystals was observed.Lane X-ray back-reflection confirmed the<001>orientation of the central crystal and deviation from the<001>direction for the edge crystals.Subgrain boundaries were monitored in the crystal.It was confirmed that orientations of all the subgrains were very close to the<001>direction.Measurement of the magnetostriction in different crystals indicated the strong anisotropy of the magnetostrictive properties.This work opens the possibility of preparing large-sized single crystal of FeGa alloys by using the Bridgman method.
基金financially supported by the National Natural Science Foundations of China (Nos.51331001 and 51520105002)the Fundamental Research Funds for Central Universities。
文摘<100>-,<112>-and <149>-oriented single crystals of Fe_(75.5)Ga_(24.5) alloy were prepared by optical float zone melting method.The pseudoelasticity behavior and elastocaloric effect of the single crystals were investigated,as well as the associate microstructures.D0_(3) phase structure was realized by solution treatment at 800 0C and annealed at 600℃ for 10 h.The compressive deformation behavior exhibits significant dependence on the crystalline directions.Excellent pseudoelasticity with recoverable strain up to 5% is obtained by compression along <149>direction.The pseudoelasticity disappears after five deformation cycles.Adiabatic temperature change is simultaneously detected during the pseudoelasticity,especially during loading process.
