The LaFe11.4Si1.6 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K （5 h） to 1623 K （2 h）. The powder X-ray diffraction （XRD） and microstructure observations show...The LaFe11.4Si1.6 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K （5 h） to 1623 K （2 h）. The powder X-ray diffraction （XRD） and microstructure observations show that large amount of 1：13 phase begins to appear in the LaFe11.4Si1.6 compound annealed at 1423 K （5 h）. In the temperature range from 1423 K to 1523 K, the α-Fe and LaFeSi phases rapidly decrease to form 1：13 phase. The LaFeSi phase is rarely observed by XRD when the as-cast compound is annealed at 1523 K （5 h）. With annealing temperature increasing to 1573 K, LaFeSi phase is detected again in LaFe11.4Si1.6 compound. In LaFe11.4Si1.6 compounds annealed at 1523 K （5 h）, at 1373 K （2 h）＋1523 K （5 h）, and 1523 K （7 h）＋1373 K （2 h）, the impurity phases including small amount of α-Fe and LaFeSi phase reduce in turn. The magnetic measurement shows that LaFe11.4Si1.6 compounds annealed by above three processes keep the first-order of magnetic transition behavior, and Tc are both at about 200 K. But the values of the maximal ASM（T, H） of has large difference, they are 9.94, 12.66, and 13.96 J/（kg.K） under a magnetic field of 0- 2 T, respectively.展开更多
The effect of Fe on microstructure and magnetic thermal performance of LaFel 1.6.xSil.4 alloys were studied by X-ray dif- fraction （XRD）, scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）,...The effect of Fe on microstructure and magnetic thermal performance of LaFel 1.6.xSil.4 alloys were studied by X-ray dif- fraction （XRD）, scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and vibrating-sample magnetometer （VSM）, respectively. The results showed that the excess Fe would make the 1：13 phase reduce in proportion and the easy corrosion phase LaFeSi phase disappear in LaFelL6＊xSil.4 alloys. The LaFel 1.6.xSil.4 alloys kept the first order magnetic phase transition, and the maximum isothermal magnetic entropy changed and the relative cooling power reached the maximum in LaFel 1.6,xSil.4 alloys with x=1.05 and 1.1, respectively.展开更多
The phase relation, microstructure, Curie temperatures, hysteresis, and magnetocaloric effects of LaFex＊11.6Si1.4 （x=0.96, 0.98, 1.0, and 1.02） compounds prepared by arc-melting and then annealed at 1423 K （1.5 h...The phase relation, microstructure, Curie temperatures, hysteresis, and magnetocaloric effects of LaFex＊11.6Si1.4 （x=0.96, 0.98, 1.0, and 1.02） compounds prepared by arc-melting and then annealed at 1423 K （1.5 h）＋1523 K （4.5 h） were investigated. The main phase was NaZn13-type phase, the impurity phases included a small amount of α-Fe and LaFeSi phase in four samples. The crystal cell parameters of 1：13 phase increased from 1.1433（5） to 1.1454（4） nm with x increasing from 0.96 to 1.02, respectively. All samples kept the typical first-order magnetic transition. The increase of Fe strengthened IEM behavior, and led to the remarkable enhancement of MCE effect and negative slopes in Arrott plots around TC. The maximum ΔSM （T, H） under a low magnetic field （0–2 T） was 15.3, 16.8, 17.9, and 24.7 J/kg K with increasing of Fe content from x=0.96 to 1.02, respectively.展开更多
基金supported by the Key Project of National Natural Science Foundation of China (Nos.50731007 and 51176050)the National High Technical Research and Development Programme of China (No.2007AA03Z440)
文摘The LaFe11.4Si1.6 compounds are prepared by arc-melting and then annealed at different high temperatures from 1323 K （5 h） to 1623 K （2 h）. The powder X-ray diffraction （XRD） and microstructure observations show that large amount of 1：13 phase begins to appear in the LaFe11.4Si1.6 compound annealed at 1423 K （5 h）. In the temperature range from 1423 K to 1523 K, the α-Fe and LaFeSi phases rapidly decrease to form 1：13 phase. The LaFeSi phase is rarely observed by XRD when the as-cast compound is annealed at 1523 K （5 h）. With annealing temperature increasing to 1573 K, LaFeSi phase is detected again in LaFe11.4Si1.6 compound. In LaFe11.4Si1.6 compounds annealed at 1523 K （5 h）, at 1373 K （2 h）＋1523 K （5 h）, and 1523 K （7 h）＋1373 K （2 h）, the impurity phases including small amount of α-Fe and LaFeSi phase reduce in turn. The magnetic measurement shows that LaFe11.4Si1.6 compounds annealed by above three processes keep the first-order of magnetic transition behavior, and Tc are both at about 200 K. But the values of the maximal ASM（T, H） of has large difference, they are 9.94, 12.66, and 13.96 J/（kg.K） under a magnetic field of 0- 2 T, respectively.
基金supported by China Postdoctoral Science Foundation(2013M542274)
文摘The effect of Fe on microstructure and magnetic thermal performance of LaFel 1.6.xSil.4 alloys were studied by X-ray dif- fraction （XRD）, scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, and vibrating-sample magnetometer （VSM）, respectively. The results showed that the excess Fe would make the 1：13 phase reduce in proportion and the easy corrosion phase LaFeSi phase disappear in LaFelL6＊xSil.4 alloys. The LaFel 1.6.xSil.4 alloys kept the first order magnetic phase transition, and the maximum isothermal magnetic entropy changed and the relative cooling power reached the maximum in LaFel 1.6,xSil.4 alloys with x=1.05 and 1.1, respectively.
基金supported by the Key Project of National Natural Science Foundation of China (50731007)the National High Technology Research and Development Program of China (2007AA03Z440)
文摘The phase relation, microstructure, Curie temperatures, hysteresis, and magnetocaloric effects of LaFex＊11.6Si1.4 （x=0.96, 0.98, 1.0, and 1.02） compounds prepared by arc-melting and then annealed at 1423 K （1.5 h）＋1523 K （4.5 h） were investigated. The main phase was NaZn13-type phase, the impurity phases included a small amount of α-Fe and LaFeSi phase in four samples. The crystal cell parameters of 1：13 phase increased from 1.1433（5） to 1.1454（4） nm with x increasing from 0.96 to 1.02, respectively. All samples kept the typical first-order magnetic transition. The increase of Fe strengthened IEM behavior, and led to the remarkable enhancement of MCE effect and negative slopes in Arrott plots around TC. The maximum ΔSM （T, H） under a low magnetic field （0–2 T） was 15.3, 16.8, 17.9, and 24.7 J/kg K with increasing of Fe content from x=0.96 to 1.02, respectively.
