The deformation behavior of V-10Cr-5Ti alloy was studied on the Gleeble-1500 thermomechanical simulator at the temperatures of 950-1350℃, and the strain rates of 0.01-10 s^-1. Based on the Arrhenius model, dislocatio...The deformation behavior of V-10Cr-5Ti alloy was studied on the Gleeble-1500 thermomechanical simulator at the temperatures of 950-1350℃, and the strain rates of 0.01-10 s^-1. Based on the Arrhenius model, dislocation density model, nucleation model and grain growth model, a numerical cellular automaton (CA) model coupling simulation of hot deformation is established to simulate and characterize the microstructural evolution during DRX. The results show that the flow stress is fairly sensitive to the strain rate and deformation temperature. The error between the predicted stress by the Arrhenius model and the actual measured value is less than 8%. The initial average grain size calculated by the CA model is 86.25 μm, which is close to the experimental result (85.63 μm). The simulations show that the effect of initial grain size on the dynamic recrystallization microstructure evolution is not significant, while increasing the strain rate or reducing the temperature can refine the recrystallized grains.展开更多
Patterned ferromagnetic thin film shows promising applications in ultra-high density magnetic storage,magnetoresistive transducer,magnetic random access memory and many other devices.Since the performance of these dev...Patterned ferromagnetic thin film shows promising applications in ultra-high density magnetic storage,magnetoresistive transducer,magnetic random access memory and many other devices.Since the performance of these devices is closely associated with the magnetic properties of the etched patterns,it is necessary to study the effects of freshly etched surface oxidation on the magnetic properties of the patterned microstructures.In the current work,were carried out an X-ray Magnetic Circular Dichroism(XMCD) study on a 50 nm Co 0.9 Fe 0.1 continuous thin film and a related patterned Co 0.9 Fe 0.1 grating structure etched with a 2 μm period.Based on the sum rules,the spin and orbital moments were calculated for these two samples,respectively.The results indicated that the spin and orbital moments of grating structure(1.34μ B and 0.24μ B,respectively) decreased 17.3% compared with the corresponding continuous film(1.62μ B and 0.29μ B,respectively).We proposed that the moment decreasing of the patterned grating structure was mainly caused by the etched surface oxidation during the pattern manufacture process.The oxidation ratio of Co element in the patterned grating structure is 14.4% calculated from X-ray absorption spectroscopy(XAS) measurement.Considering the oxidation ratio,we amend the spin and orbital moment of Co and the amended result is basically in accordance with that of continuous film,demonstrating that the difference of the spin and orbital moments between the sub-micron grating unit and the continuous film is really caused by the oxidation.展开更多
基金Project(51405110)supported by the National Natural Science Foundation of ChinaProject(20132302120002)supported by the Specialized Research Fund for the Doctoral Program of Higher Education,ChinaProject(LBH-Z14096)supported by Heilongjiang Province Postdoctoral Fund,China
文摘The deformation behavior of V-10Cr-5Ti alloy was studied on the Gleeble-1500 thermomechanical simulator at the temperatures of 950-1350℃, and the strain rates of 0.01-10 s^-1. Based on the Arrhenius model, dislocation density model, nucleation model and grain growth model, a numerical cellular automaton (CA) model coupling simulation of hot deformation is established to simulate and characterize the microstructural evolution during DRX. The results show that the flow stress is fairly sensitive to the strain rate and deformation temperature. The error between the predicted stress by the Arrhenius model and the actual measured value is less than 8%. The initial average grain size calculated by the CA model is 86.25 μm, which is close to the experimental result (85.63 μm). The simulations show that the effect of initial grain size on the dynamic recrystallization microstructure evolution is not significant, while increasing the strain rate or reducing the temperature can refine the recrystallized grains.
基金supported by the National Natural Science Foundation of China (Grant No. 10274073)the Post-doctoral Research Start-up Funding of Anhui University of Architecture (Grant No. K02553)the Open Project of Building Energy Conservation Institute of Anhui University of Architecture (Grant No. K02592)
文摘Patterned ferromagnetic thin film shows promising applications in ultra-high density magnetic storage,magnetoresistive transducer,magnetic random access memory and many other devices.Since the performance of these devices is closely associated with the magnetic properties of the etched patterns,it is necessary to study the effects of freshly etched surface oxidation on the magnetic properties of the patterned microstructures.In the current work,were carried out an X-ray Magnetic Circular Dichroism(XMCD) study on a 50 nm Co 0.9 Fe 0.1 continuous thin film and a related patterned Co 0.9 Fe 0.1 grating structure etched with a 2 μm period.Based on the sum rules,the spin and orbital moments were calculated for these two samples,respectively.The results indicated that the spin and orbital moments of grating structure(1.34μ B and 0.24μ B,respectively) decreased 17.3% compared with the corresponding continuous film(1.62μ B and 0.29μ B,respectively).We proposed that the moment decreasing of the patterned grating structure was mainly caused by the etched surface oxidation during the pattern manufacture process.The oxidation ratio of Co element in the patterned grating structure is 14.4% calculated from X-ray absorption spectroscopy(XAS) measurement.Considering the oxidation ratio,we amend the spin and orbital moment of Co and the amended result is basically in accordance with that of continuous film,demonstrating that the difference of the spin and orbital moments between the sub-micron grating unit and the continuous film is really caused by the oxidation.
