Effect of Ce-rich rare earth on microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy

To improve the comprehensive mechanical properties of Mg-10Zn-5Al-0.1Sb magnesium alloy, different amount of Ce-rich rare earth （RE） was added to the alloy, and the effect of RE addition on the microstructure and mechanical properties of Mg-10Zn-5Al-0.1Sb alloy was investigated by means of Brinell hardness measurement, scanning electron microscopy （SEM）, energy dispersive spectroscope （EDS） and X-ray diffraction （XRD）. The results show that an appropriate amount of Ce-rich rare earth addition can make the AI4Ce phase particles and CeSb phase disperse more evenly in the alloy. These phases refine the alloy＇s matrix and make the secondary phases [τ-Mg32（AI,Zn）49 phase and φ-Al2MgsZn2 phase] finer and more dispersive, therefore significantly improve the mechanical properties of the Mg-10Zn-5AI-0,1Sb alloy. When the RE addition is 1.0 wt.%, the tensile strengths of the alloy both at room temperature and 150℃ reach the maximum values while the impact toughness is slightly lower than that of the matrix alloy. The hardness increases with the increase of RE addition.

Effect of Ce-rich mish metals and electromagnetic stirring on microstructure of AZ91D magnesium alloy

The influence of Ce-rich mish metal（MM） and electromagnetic stirring（EMS） on microstructure evolution of AZ91D magnesium alloy was investigated by optical microscopy, scanning electron microscopy（SEM）, energy dispersion spectrum（EDS） and X-ray diffraction（XRD）. The microstructure of AZ91D and alloying AZ91D is different. Except dominant primary α（Mg） and β-Mg 17Al 12 in AZ91D, a new phase Al 11MM3 is observed in alloyed AZ91D. Increasing Ce-rich MM, primary α grains can be refined, the content and grain size of β obviously decrease, furthermore, its morphology degrades from discontinuous network to separated particles, and Al 11MM3 amount substantially increases and acicular Al 11MM3 aggregates into clusters at grain boundaries. In EMS process, α morphology evolves from rosette to sphere, and then spherical-like with the decrease of isothermal stirring temperature. Moreover, Al 11MM3 mainly distributes inside primary grains and eutecticum in form of short-rod. EMS can alter not only the primary morphology but Al 11MM3.

Magnetic properties of misch-metal partially substituted Nd–Fe–B magnets sintered by dual alloy method

The misch-metal （MM） partially substituted Nd-Fe-B sintered magnets were fabricated by the dual alloy method, and the crystal structure, microstructure, and magnetic properties were analyzed comprehensively. X-ray diffraction （XRD） reveals that the increasing content of the MM has an inconsiderable effect on the crystallographic alignment of the magnets. Grains of the two main phases are uniformly distributed, and slightly deteriorate on the grain boundary. Due to the diffusion between the adjacent grains, the MM substituted Nd-Fe-B magnets contain three types of components with different Ce/La concentrations. Moreover, the first-order reversal curve （FORC） diagram is introduced to analyze the magnetization reversal process, coercivity mechanism, and distribution of reversal field in magnetic samples. The analysis indicates that there are two major reversal components, corresponding to the two different main phases. The domain nucleation and growth are determined to be the leading mechanism in controlling the magnetization reversal processes of the magnets sintered by the dual alloy method.

XPS Analysis of the Cerium Conversion Coating on the Anodized A16061/SiC_p

A method of concentration analysis based on X-ray photoelectron spectroscopy (XPS) results was introduced. The concentration of Ce-rich conversion coating on the anodized Al based metal matrix composites AI6061/SiCp was then studied according to this method. The results revealed that the Ce conversion coating on the anodized AI6061/SiCp consisted of Al oxide, Ce oxide and Ce hydroxide. The state of Ce element exhibited the mixture of Ce3+ and Ce4+. Some of Cell I was oxidized to be CelV in the outer layer coating.

Microstructural design in LaCe misch-metal substituted 2:14:1-type sintered magnets by dual-alloy method

LaCe-based sintered magnets with different microstructural features and distinct rare earth elemental distribution were designed by dual-alloy method.The sample prepared by fine LaCe-containing powder and coarse LaCe-free powder possesses higher remanence(~13.41 kGs),whereas another sample prepared by fine LaCe-free powder and coarse LaCe-containing powder possesses higher coercivity(~5.67 kOe).Additionally,these samples are with the same nominal compositions and their elemental distribution features are obviously different in matrix grains respectively.Their remanence difference is mainly affected by the saturation magnetization difference caused by the distribution variation of the rare earth elements at the matrix phase.The coercivity difference is affected by the component of the grain boundary phase between the adjacent grains and the distribution variation of the rare earth elements at the matrix phase.These findings may provide a new prospect for the utilization of LaCe mischmetal in 2:14:1-type permanent magnets.

Dependence of magnetic properties on microstructure and composition of Ce-Fe-B sintered magnets

In this paper,dependence of magnetic properties on microstructure and composition of Ce-Fe-B sintered magnets with Cu-doped Ce-rich alloy addition was investigated.It shows that the maximum energy product(BH)(max)and coercivity H(cj)of Ce-Fe-B sintered magnet are improved from 6.76 to 9.13 MGOe by 35.1%,and from 1.44 to 1.67 kOe by 16.0%,respectively,via adding 5 wt%liquid phase alloy of Ce(35.58)Fe(57.47)Cu6 B(0.95)(at%).Compared with the magnet without Cerich alloy addition,the volume fraction of the grain-boundary phase with low melting point increases in the magnet with Ce-rich alloy additio n,which is be ne ficial to imp roving the microstructure and promoting the coercivity enhancement of the magnet.In the Ce-Fe-B magnet with Ce-rich alloy addition,Cu and Ce enrich in the grain boundaries of the magnet after annealing,therefore the as-annealed magnet has a higher coercivity than the as-sintered magnet.A distinct Fe-rich layer with the average thickness of 60 nm is found in the grain boundaries in the magnet without Ce-rich alloy addition,but it seems that Fe-rich phase disappears in the magnet with Ce-rich alloy addition.The present work suggests that the further improvement of coercivity in the Ce-Fe-B sintered magnets is expectable by designing the composition and structure of added liquid phase alloys.

Structure and intrinsic magnetic properties of MM_2Fe_(14)B(MM=La,Ce,Pr,Nd)alloys

MM_（33）Fe_（66）B（MM=La, Ce, Pr, Nd） alloys（mass ratio） were prepared by induction melting and heat-treated at 1353 K for 24 h to produce homogeneous MM_2Fe_（14） B phase. The phase structure and element distribution of the alloys were analyzed by X-ray diffraction（XRD） and scanning electron microscope（SEM）. The alloys were applied ball milling to obtain powders with good size distribution and then magnetic aligned in a static magnetic field of 2 T for 4 h, in order to achieve the intrinsic magnetic properties by vibrating sample magnetometer（VSM）. XRD results showed that the alloys were composed of the single 2：14：1 main phase and RE-rich phase, which was similar to Nd_2Fe_（14）B structure. Magnetic measurements showed that the saturation magnetization（Ms） and anisotropy field（HA） of the MM_（33）Fe_（66）B alloy were 11.3 k Gs and 48.4 k Oe, respectively, demonstrating its good potential as permanent magnets. The Curie temperature of the MM_（33）Fe_（66）B alloy was determined as 502.9 K by magnetization-temperature curves. Microstructure observation showed that Nd and Pr were mainly in the 2：14：1 ferromagnetic phase, while La and Ce prefered to aggregate in the RE-rich grain boundary phase, which is beneficial to fabricating（Pr, Nd, MM）_2Fe_（14）B magnets with good magnetic properties.