The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composi- tion of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magne...The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composi- tion of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method was discussed, which is a method blend- ing two-type main phase alloy powders with different components. The results showed that the intrinsic coercivity and density of sin- tered Nd-Fe-B magnets increased gradually with the increase in Dy content, and the double-alloy powder mixed method could obtain high intrinsic coercivity Nd-Fe-B magnets with good crystallographic alignment and microstructure. The bending strength of sintered Nd-Fe-B magnets declined, and the Rockwell hardness of sintered Nd-Fe-B magnets first declined, and then increased with the in- crease in Dy content. The microstructure showed that there existed the phenomenon that the Dy element diffused into main phase dur- ing sintering process, and the distribution of Dy content in main phase had some variation in homogeneity as a result of incomplete reaction between the double-alloy powder types.展开更多
The mechanical properties of die-upset Nd-Fe-B magnets produced at different die-upset processes were investigated. The results showed that the optimum comprehensive mechanical properties of die-upset Nd-Fe-B magnets ...The mechanical properties of die-upset Nd-Fe-B magnets produced at different die-upset processes were investigated. The results showed that the optimum comprehensive mechanical properties of die-upset Nd-Fe-B magnets were obtained at the deformation temperature of 680 ℃. The anisotropy of Vickers hardness was more obvious at the die-upset level of 55%, and the Vickers hardness measured parallel to the c-axis was significantly lower than that perpendicular to the c-axis. The fracture toughness measured parallel to the c-axis first increased, and then decreased with increase in die-upset level. The maximum fracture toughness of Nd-Fe-B magnets was obtained at the die-upset level of 60%. The microstmcture showed that the width of defect layers and the average size of large grains increased, and the layered structure of die-upset Nd-Fe-B magnets was obviously different with increase in the die-upset level.展开更多
Additive manufacturing(AM),also known as 3D-printing(3DP)technology,is an advanced manufacturing technology that has developed rapidly in the past 40 years.However,the ceramic material printing is still challenging be...Additive manufacturing(AM),also known as 3D-printing(3DP)technology,is an advanced manufacturing technology that has developed rapidly in the past 40 years.However,the ceramic material printing is still challenging because of the issue of cracking.Indirect 3D printing has been designed and drawn attention because of its high manufacturing speed and low cost.Indirect 3D printing separates the one-step forming process of direct 3D printing into binding and material sintering,avoiding the internal stress caused by rapid cooling,making it possible to realize the highquality ceramic component with complex shape.This paper presents the research progress of leading indirect 3D printing technologies,including binder jetting(BJ),stereolithography(SLA),and fused deposition modeling(FDM).At present,the additive manufacturing of ceramic materials is mainly achieved through indirect 3D printing technology,and these materials include silicon nitride,hydroxyapatite functional ceramics,silicon carbide structural ceramics.展开更多
Mg-20wt.%Fe_(23)Y_(8) composite was successfully prepared by reactive mechanical alloying(RMA).X-ray diffraction(XRD)measurement shows that the main phases of composite are MgH_(2) and Mg2FeH6.The composite exhibits e...Mg-20wt.%Fe_(23)Y_(8) composite was successfully prepared by reactive mechanical alloying(RMA).X-ray diffraction(XRD)measurement shows that the main phases of composite are MgH_(2) and Mg2FeH6.The composite exhibits excellent hydrogen abs/desorption properties and can absorb 4.36wt.%and 5.72wt.%hydrogen at 473 and 573 K in 10 min under 3.0 MPa hydrogen pressure,respectively.The composite can desorb 5.27wt.%hydrogen at 573 K in 30 min under 0.02 MPa hydrogen pressure.Compared with the pure MgH_(2),the hydrogen desorption temperature of Mg-20wt.%Fe_(23)Y_(8) composite is decreased about 40℃.It is supposed that both the catalyst effect of Fe-Y distributed in Mg substrate and the crystal defects play the main role in improving hydrogen sorption properties of Mg-20wt.%Fe_(23)Y_(8) composite.展开更多
基金Project supported by the Natural Science Foundation of Hubei Province(2014CFB626,2015CFC785)the Research Project of Hubei Provincial Department of Education(D20151801)the Opening Foundation of Hubei Key Laboratory of Automotive Power Train and Electronic Control(ZDK1201404)
文摘The double-alloy powder mixed method is very proper for developing new small-mass products by changing the composi- tion of sintered Nd-Fe-B magnets, and there is little research on this aspect. The variation on magnetic and mechanical properties of high intrinsic coercivity Nd-Fe-B magnets prepared by double-alloy powder mixed method was discussed, which is a method blend- ing two-type main phase alloy powders with different components. The results showed that the intrinsic coercivity and density of sin- tered Nd-Fe-B magnets increased gradually with the increase in Dy content, and the double-alloy powder mixed method could obtain high intrinsic coercivity Nd-Fe-B magnets with good crystallographic alignment and microstructure. The bending strength of sintered Nd-Fe-B magnets declined, and the Rockwell hardness of sintered Nd-Fe-B magnets first declined, and then increased with the in- crease in Dy content. The microstructure showed that there existed the phenomenon that the Dy element diffused into main phase dur- ing sintering process, and the distribution of Dy content in main phase had some variation in homogeneity as a result of incomplete reaction between the double-alloy powder types.
基金supported by National Natural Science Foundation of China (50801049)
文摘The mechanical properties of die-upset Nd-Fe-B magnets produced at different die-upset processes were investigated. The results showed that the optimum comprehensive mechanical properties of die-upset Nd-Fe-B magnets were obtained at the deformation temperature of 680 ℃. The anisotropy of Vickers hardness was more obvious at the die-upset level of 55%, and the Vickers hardness measured parallel to the c-axis was significantly lower than that perpendicular to the c-axis. The fracture toughness measured parallel to the c-axis first increased, and then decreased with increase in die-upset level. The maximum fracture toughness of Nd-Fe-B magnets was obtained at the die-upset level of 60%. The microstmcture showed that the width of defect layers and the average size of large grains increased, and the layered structure of die-upset Nd-Fe-B magnets was obviously different with increase in the die-upset level.
基金Project(51901020)supported by the National Natural Science Foundation of ChinaProject(2019JZZY010327)supported by Shandong Key Research and Development Plan,China+1 种基金Project(201942074001)supported by Aeronautical Science Foundation of ChinaProject(FRF-IP-20-05)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Additive manufacturing(AM),also known as 3D-printing(3DP)technology,is an advanced manufacturing technology that has developed rapidly in the past 40 years.However,the ceramic material printing is still challenging because of the issue of cracking.Indirect 3D printing has been designed and drawn attention because of its high manufacturing speed and low cost.Indirect 3D printing separates the one-step forming process of direct 3D printing into binding and material sintering,avoiding the internal stress caused by rapid cooling,making it possible to realize the highquality ceramic component with complex shape.This paper presents the research progress of leading indirect 3D printing technologies,including binder jetting(BJ),stereolithography(SLA),and fused deposition modeling(FDM).At present,the additive manufacturing of ceramic materials is mainly achieved through indirect 3D printing technology,and these materials include silicon nitride,hydroxyapatite functional ceramics,silicon carbide structural ceramics.
基金This work was financially supported by the Ministry of Science and Technology of China(No.2003AA518010).
文摘Mg-20wt.%Fe_(23)Y_(8) composite was successfully prepared by reactive mechanical alloying(RMA).X-ray diffraction(XRD)measurement shows that the main phases of composite are MgH_(2) and Mg2FeH6.The composite exhibits excellent hydrogen abs/desorption properties and can absorb 4.36wt.%and 5.72wt.%hydrogen at 473 and 573 K in 10 min under 3.0 MPa hydrogen pressure,respectively.The composite can desorb 5.27wt.%hydrogen at 573 K in 30 min under 0.02 MPa hydrogen pressure.Compared with the pure MgH_(2),the hydrogen desorption temperature of Mg-20wt.%Fe_(23)Y_(8) composite is decreased about 40℃.It is supposed that both the catalyst effect of Fe-Y distributed in Mg substrate and the crystal defects play the main role in improving hydrogen sorption properties of Mg-20wt.%Fe_(23)Y_(8) composite.
