Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46～125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the gr...Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46～125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the ground powders (remanence B r=～0.95 T, coercivity H cj =～227 kA·m -1 and maximum energy product (BH) max=～48 8 kJ·m -3) was observed in accordance with increasing temperature up to 800 ℃. The sorbing temperature and time for Yb metal vapor were optimized and after heating at 800 ℃ for 90 min and annealing subsequently at 610 ℃ for 60 min, the B r, H cj and (BH) max values were increased to be 0.98 T, 712 kA·m -1 and 173 kJ·m -3, respectively. From the microstructural characterizations of resulting samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe X-ray microanalyzer (EPMA), it is found that the sorbed Yb metal uniformly covers the surface and diffuses to the Nd-rich grain boundary of fine ground powders of Nd-Fe-B sintered magnet bulks forming a (Nd,Yb)Fe 2 phase.展开更多
The Madi rare metal granite is a complex massif,which contains a variety of rare metals,such as Nb,Ta,Li,and Be.In this paper,the geochemical characteristics of the granite were obtained by multi-collector inductively...The Madi rare metal granite is a complex massif,which contains a variety of rare metals,such as Nb,Ta,Li,and Be.In this paper,the geochemical characteristics of the granite were obtained by multi-collector inductively coupled mass spectrometry(MC-ICP-MS).The precise crystalline age of the granite was obtained from monazite U-Pb dating,and the source of the granite was determined using Li-Nd isotopes.The Madi rare metal granite is a high-K(calc-alkaline),peraluminous,S-type granite.The U-Pb monazite age indicates that the crystalline age of the granite is 175.6 Ma,which is Early Jurassic.The granite is characterized by a relatively wide range ofδ7 Li values(+2.99‰to+5.83‰)and high lithium concentrations(181 ppm to 1022 ppm).The lithium isotopic composition of the granite does not significantly correlate with the degree of magmatic differentiation.An insignificant amount of lithium isotope fractionation occurred during the granitic differentiation.The lithium isotopic composition of the granite significantly differs from that of the wall rock,but it is very similar to that of a primitive mantle peridotite xenolith(meanδ7 Li value+3.5‰).The plot of Li concentration versusδ7 Li indicates that the Li isotopic composition of the granite is similar to that of island arc lavas.Based on the above-described evidence,the granite was mainly derived from the crust,but it was contaminated by a deep granitic magma.展开更多
文摘Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46～125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the ground powders (remanence B r=～0.95 T, coercivity H cj =～227 kA·m -1 and maximum energy product (BH) max=～48 8 kJ·m -3) was observed in accordance with increasing temperature up to 800 ℃. The sorbing temperature and time for Yb metal vapor were optimized and after heating at 800 ℃ for 90 min and annealing subsequently at 610 ℃ for 60 min, the B r, H cj and (BH) max values were increased to be 0.98 T, 712 kA·m -1 and 173 kJ·m -3, respectively. From the microstructural characterizations of resulting samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe X-ray microanalyzer (EPMA), it is found that the sorbed Yb metal uniformly covers the surface and diffuses to the Nd-rich grain boundary of fine ground powders of Nd-Fe-B sintered magnet bulks forming a (Nd,Yb)Fe 2 phase.
基金the project of“Comprehensive integration and service of mineral geology and its metallogenic regularity in China”from China Geological Survey(Grant No.DD20160346)
文摘The Madi rare metal granite is a complex massif,which contains a variety of rare metals,such as Nb,Ta,Li,and Be.In this paper,the geochemical characteristics of the granite were obtained by multi-collector inductively coupled mass spectrometry(MC-ICP-MS).The precise crystalline age of the granite was obtained from monazite U-Pb dating,and the source of the granite was determined using Li-Nd isotopes.The Madi rare metal granite is a high-K(calc-alkaline),peraluminous,S-type granite.The U-Pb monazite age indicates that the crystalline age of the granite is 175.6 Ma,which is Early Jurassic.The granite is characterized by a relatively wide range ofδ7 Li values(+2.99‰to+5.83‰)and high lithium concentrations(181 ppm to 1022 ppm).The lithium isotopic composition of the granite does not significantly correlate with the degree of magmatic differentiation.An insignificant amount of lithium isotope fractionation occurred during the granitic differentiation.The lithium isotopic composition of the granite significantly differs from that of the wall rock,but it is very similar to that of a primitive mantle peridotite xenolith(meanδ7 Li value+3.5‰).The plot of Li concentration versusδ7 Li indicates that the Li isotopic composition of the granite is similar to that of island arc lavas.Based on the above-described evidence,the granite was mainly derived from the crust,but it was contaminated by a deep granitic magma.
