Amorphous ribbons of the alloy Fe73.5 Si13.5B9Cu1Nb1V2 were prepared by the standard single copper wheel melt spinning technique in the air atmosphere. The crystallization kinetics of amorphous ribbons was analyzed by...Amorphous ribbons of the alloy Fe73.5 Si13.5B9Cu1Nb1V2 were prepared by the standard single copper wheel melt spinning technique in the air atmosphere. The crystallization kinetics of amorphous ribbons was analyzed by non-isothermal differential scanning calorimetry （DSC） measurements. The crystallization activation energies of amorphous ribbons calculated by using Kissinger model were 364 and 337 kJ/mol for the first and the second crystallization, respectively. The Avrami exponent n was calculated from the Johnson- Mehl-Avrami （ MA） equation. The value of the Avrami exponent showed that the crystallization mechanism in the non-isothermal primary crystallization of amorphous ribbons was all shapes growing from small dimensions controlled by diffusion at decreasing nuclectcn rate. The variation of soft magnetic properties of nanocrystalline Fe73.5 Si13.5B9Cu1Nb1V2 alloy powder cores s a tunction of milling times has been investigated. It is found that the effective permeability of the cores shows high frequency stability and decreases with the increase of milling times. The quality factor increases with increasing frequency in lower frequency range, and reaches a maximum at the frequency of 80 kHz then decreases gradually with increasing frequency.展开更多
Magnetic transitions and magnetotransport properties of polycrystalline Er1-xGdxMn6Ge6（x=0.2-0.9） compounds were studied.The magnetic and resistivity properties were analyzed in an applied magnetic field up to 5 T.I...Magnetic transitions and magnetotransport properties of polycrystalline Er1-xGdxMn6Ge6（x=0.2-0.9） compounds were studied.The magnetic and resistivity properties were analyzed in an applied magnetic field up to 5 T.It is found that Er1-xGdxMn6Ge6（x=0.2-0.9） compounds displays a transition from the antiferromagnetic state to the ferrimagnetic state for increasing Gd content.The Er1-xGdx Mn6Ge6 with x=0.2 and 0.5 compounds order antiferromagnetically at 430 and 432 K,respectively.The Er1-x GdxMn6Ge6 with x=0.8 and 0.9 compounds order ferrimagnetically at 462 and 471 K,respectively.The Er1-xGdxMn6Ge6 compounds undergo the second transitions below 71 K.The magnetoresistance curves of the Er0.1Gd0.9Mn6Ge6 compound in a field of 5 T are presented and the magnetoresistance effects are related to the metamagnetic transitions.展开更多
The unit cell volume and phase transition temperature of LaFe11.4Al1.6Cx compounds have been studied. The magnetic entropy change, refrigerant capacity and the type of magnetic phase transition are investigated in det...The unit cell volume and phase transition temperature of LaFe11.4Al1.6Cx compounds have been studied. The magnetic entropy change, refrigerant capacity and the type of magnetic phase transition are investigated in detail for LaFe11.4Al1.6Cx with x=0.1, All the LaFe11.4Al1.6Cx （x=0-0.8） compounds have the cubic NaZn13-type structure. The addition of carbon atoms brings about a considerable increase in the lattice parameter. The bulk expansion results in the change of phase transition temperature （Tc）, Tc increases from 187K to 269 K with x varying from 0.1 to 0.8, Meanwhile an increase in the lattice parameter can also cause a change of the magnetic ground state from antiferromagnetic to ferromagnetic. Large magnetic entropy change IASI is found over a large temperature range around Tc and the refrigerant capacity is about 322J/kg for LaFe11.4Al1.6C0.1. The magnetic phase transition belongs in weakly first-order one for x=0.1.展开更多
基金Funded by the State Key Lab of Advanced Metals and Materials(No.2011-ZD03)The Hubei Provincial Department of Education(No.D20111103)
文摘Amorphous ribbons of the alloy Fe73.5 Si13.5B9Cu1Nb1V2 were prepared by the standard single copper wheel melt spinning technique in the air atmosphere. The crystallization kinetics of amorphous ribbons was analyzed by non-isothermal differential scanning calorimetry （DSC） measurements. The crystallization activation energies of amorphous ribbons calculated by using Kissinger model were 364 and 337 kJ/mol for the first and the second crystallization, respectively. The Avrami exponent n was calculated from the Johnson- Mehl-Avrami （ MA） equation. The value of the Avrami exponent showed that the crystallization mechanism in the non-isothermal primary crystallization of amorphous ribbons was all shapes growing from small dimensions controlled by diffusion at decreasing nuclectcn rate. The variation of soft magnetic properties of nanocrystalline Fe73.5 Si13.5B9Cu1Nb1V2 alloy powder cores s a tunction of milling times has been investigated. It is found that the effective permeability of the cores shows high frequency stability and decreases with the increase of milling times. The quality factor increases with increasing frequency in lower frequency range, and reaches a maximum at the frequency of 80 kHz then decreases gradually with increasing frequency.
基金Funded by the The Hubei Province Key Laboratory of Systems Science in Metallurgical Process (No. C201020)National Natural Science Foundation of China(Nos. 10804089,10805035)
文摘Magnetic transitions and magnetotransport properties of polycrystalline Er1-xGdxMn6Ge6（x=0.2-0.9） compounds were studied.The magnetic and resistivity properties were analyzed in an applied magnetic field up to 5 T.It is found that Er1-xGdxMn6Ge6（x=0.2-0.9） compounds displays a transition from the antiferromagnetic state to the ferrimagnetic state for increasing Gd content.The Er1-xGdx Mn6Ge6 with x=0.2 and 0.5 compounds order antiferromagnetically at 430 and 432 K,respectively.The Er1-x GdxMn6Ge6 with x=0.8 and 0.9 compounds order ferrimagnetically at 462 and 471 K,respectively.The Er1-xGdxMn6Ge6 compounds undergo the second transitions below 71 K.The magnetoresistance curves of the Er0.1Gd0.9Mn6Ge6 compound in a field of 5 T are presented and the magnetoresistance effects are related to the metamagnetic transitions.
基金Project supported by the State Key Program of Basic Research of China （Grant No 2006CB601101）, and the National Natural Science Foundation of China （ Grant No 50271082）.
文摘The unit cell volume and phase transition temperature of LaFe11.4Al1.6Cx compounds have been studied. The magnetic entropy change, refrigerant capacity and the type of magnetic phase transition are investigated in detail for LaFe11.4Al1.6Cx with x=0.1, All the LaFe11.4Al1.6Cx （x=0-0.8） compounds have the cubic NaZn13-type structure. The addition of carbon atoms brings about a considerable increase in the lattice parameter. The bulk expansion results in the change of phase transition temperature （Tc）, Tc increases from 187K to 269 K with x varying from 0.1 to 0.8, Meanwhile an increase in the lattice parameter can also cause a change of the magnetic ground state from antiferromagnetic to ferromagnetic. Large magnetic entropy change IASI is found over a large temperature range around Tc and the refrigerant capacity is about 322J/kg for LaFe11.4Al1.6C0.1. The magnetic phase transition belongs in weakly first-order one for x=0.1.
