X-ray diffraction (XRD) and differential scanning calorimetry (DSC) wereemployed to investigate the influence of Ni content on the crystallization of amorphousZr_(70)Cu_(30-x)Ni_x (atom fraction in percent) alloys. Ex...X-ray diffraction (XRD) and differential scanning calorimetry (DSC) wereemployed to investigate the influence of Ni content on the crystallization of amorphousZr_(70)Cu_(30-x)Ni_x (atom fraction in percent) alloys. Experimental results show that with the Nicontent increasing the activation energies for crystallization of amorphous Zr_(70)Cu_(30-x)Ni_xalloys increase correspondingly, indicating that the thermal stability is greatly improved. All theDSC traces of amorphous Zr_(70)Cu_(30-x)Ni_x alloys exhibit two exothermic peaks, suggesting thatthe crystallization process proceeds via a double-stage mode. The first exothermic peak at lowertemperature mainly corresponds to the precipitation and growth of Zr_2Cu particles, while the secondone corresponds to the precipitation of nano-scale Zr_2Ni phase and crystallization of residualamorphous phase. The mechanism on the crystallization of amorphous Zr_(70)Cu_(30-x)Ni_x alloys wasdiscussed.展开更多
Crystallization temperature of the metallic glass Zr_(70)Cu_(30),observed by X-ray diffraction analysis,may be increased about 20℃,the superior limit of increase range of the temperature is about 30℃,under high pres...Crystallization temperature of the metallic glass Zr_(70)Cu_(30),observed by X-ray diffraction analysis,may be increased about 20℃,the superior limit of increase range of the temperature is about 30℃,under high pressure up to 2GPa.Besides α-Zr and CuZr_2, the Cu_(10)Zr_7 phase was newly obtained as another crystallization product.展开更多
Usually it is generally believed that the Er element forms the Er_(2)Fe_(14)B phase,which will seriously deteriorate the magnetic properties.Distinctly,here we report the balance of corrosion resistance and coercivity...Usually it is generally believed that the Er element forms the Er_(2)Fe_(14)B phase,which will seriously deteriorate the magnetic properties.Distinctly,here we report the balance of corrosion resistance and coercivity in Nd-Fe-B sintered magnets through using simple Er_(30)Cu_(70) additive whose price is much lower than Dy and Tb.By reasonably controlling Er_(30)Cu_(70) addition,the corrosion resistance is improved at the minimum limit of reducing the magnetic properties.Through studying the influence mechanism of Er element,it is found that the main effect of Er elements is to replace the Nd elements at the edge of the main phase grains to form a(Er,Nd)_(2)Fe_(14)B shell with low H_(A),resulting in the reduction of magnetic properties.The improvement of corrosion resistance mainly comes from the more stable Cu element introduced at the grain boundary.At the same time,the target magnets also show different advantages under different heat treatment methods.Above findings may spur progress towards developing the lowcost permanent magnets that rival the commercial Nd-Fe-B counterpart.展开更多
Grain boundary diffusion process(GBDP)has been developed as an effective approach to increase the coercivity of sintered Nd-Fe-B magnets by regulating the compositions and phase distributions near grain boundaries.Thi...Grain boundary diffusion process(GBDP)has been developed as an effective approach to increase the coercivity of sintered Nd-Fe-B magnets by regulating the compositions and phase distributions near grain boundaries.This work aims to explore how to select the optimum annealing temperature after GBDP.In this work GBDP was performed on a sintered Nd-Fe-B magnet using Dy_(70)Cu_(30) alloy.After GBDP the low eutectic temperature of the grain boundary phases decreases from the initial 492 to 451℃.The magnetic property dependent on different annealing temperatures near the low eutectic temperature was studied.The magnetic properties,especially the squareness factor of demagnetization curve show a strong dependence on the annealing temperature.After GBDP the optimal magnetic properties can be obtained after annealing just above the low eutectic temperature of the grain boundary phases.The mechanism is discussed based on the microstructure analysis.展开更多
In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XR...In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),atomic force microscopy(AFM),hardness tester and nano indentation.Corrosion behavior of the film was investigated in 3.5%NaCl aqueous solutions by an electrochemical method.At room temperature,the amorphous alloy film was formed completely after sputtering for 5 h.The surface morphology of the amorphous alloy film was uniform and smooth.Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate.The amorphous alloy film(prepared at room temperature for 5 h)exhibited good adhesion strength with the substrate.The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short(1 h)or too long(10 h).展开更多
基金This work is financially supported by the National Natural Science Foundation of China (No. 59871025).
文摘X-ray diffraction (XRD) and differential scanning calorimetry (DSC) wereemployed to investigate the influence of Ni content on the crystallization of amorphousZr_(70)Cu_(30-x)Ni_x (atom fraction in percent) alloys. Experimental results show that with the Nicontent increasing the activation energies for crystallization of amorphous Zr_(70)Cu_(30-x)Ni_xalloys increase correspondingly, indicating that the thermal stability is greatly improved. All theDSC traces of amorphous Zr_(70)Cu_(30-x)Ni_x alloys exhibit two exothermic peaks, suggesting thatthe crystallization process proceeds via a double-stage mode. The first exothermic peak at lowertemperature mainly corresponds to the precipitation and growth of Zr_2Cu particles, while the secondone corresponds to the precipitation of nano-scale Zr_2Ni phase and crystallization of residualamorphous phase. The mechanism on the crystallization of amorphous Zr_(70)Cu_(30-x)Ni_x alloys wasdiscussed.
文摘Crystallization temperature of the metallic glass Zr_(70)Cu_(30),observed by X-ray diffraction analysis,may be increased about 20℃,the superior limit of increase range of the temperature is about 30℃,under high pressure up to 2GPa.Besides α-Zr and CuZr_2, the Cu_(10)Zr_7 phase was newly obtained as another crystallization product.
基金Project supported by the Natural Science Foundation of Guangxi(2021GXNSFDA075009)the National Natural Science Foundation of China(52261004)。
文摘Usually it is generally believed that the Er element forms the Er_(2)Fe_(14)B phase,which will seriously deteriorate the magnetic properties.Distinctly,here we report the balance of corrosion resistance and coercivity in Nd-Fe-B sintered magnets through using simple Er_(30)Cu_(70) additive whose price is much lower than Dy and Tb.By reasonably controlling Er_(30)Cu_(70) addition,the corrosion resistance is improved at the minimum limit of reducing the magnetic properties.Through studying the influence mechanism of Er element,it is found that the main effect of Er elements is to replace the Nd elements at the edge of the main phase grains to form a(Er,Nd)_(2)Fe_(14)B shell with low H_(A),resulting in the reduction of magnetic properties.The improvement of corrosion resistance mainly comes from the more stable Cu element introduced at the grain boundary.At the same time,the target magnets also show different advantages under different heat treatment methods.Above findings may spur progress towards developing the lowcost permanent magnets that rival the commercial Nd-Fe-B counterpart.
基金Project supported by the National Natural Science Foundation of China(51901087)Natural Science Foundation of Jiangsu Province(BK20190975,BK20201007)+1 种基金China Postdoctoral Science Foundation(2021M701504)Natural Science Foundation for Colleges and Universities in Jiangsu Province(20KJD470002)。
文摘Grain boundary diffusion process(GBDP)has been developed as an effective approach to increase the coercivity of sintered Nd-Fe-B magnets by regulating the compositions and phase distributions near grain boundaries.This work aims to explore how to select the optimum annealing temperature after GBDP.In this work GBDP was performed on a sintered Nd-Fe-B magnet using Dy_(70)Cu_(30) alloy.After GBDP the low eutectic temperature of the grain boundary phases decreases from the initial 492 to 451℃.The magnetic property dependent on different annealing temperatures near the low eutectic temperature was studied.The magnetic properties,especially the squareness factor of demagnetization curve show a strong dependence on the annealing temperature.After GBDP the optimal magnetic properties can be obtained after annealing just above the low eutectic temperature of the grain boundary phases.The mechanism is discussed based on the microstructure analysis.
基金financially supported by the National Natural Science Foundation of China(No.51771131)。
文摘In this work,amorphous Zr_(55)Al_(10)Ni_(5)Cu_(30)alloy thin film was prepared on D36 steel substrate by magnetron sputtering method.The film was characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),atomic force microscopy(AFM),hardness tester and nano indentation.Corrosion behavior of the film was investigated in 3.5%NaCl aqueous solutions by an electrochemical method.At room temperature,the amorphous alloy film was formed completely after sputtering for 5 h.The surface morphology of the amorphous alloy film was uniform and smooth.Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate.The amorphous alloy film(prepared at room temperature for 5 h)exhibited good adhesion strength with the substrate.The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short(1 h)or too long(10 h).
