Development of cost-effective nanocrystalline multi-component(Ce,La,Y)-Fe-B permanent magnetic alloys containing no critical rare earth elements of Dy,Tb,Pr and Nd

Here we first report the fully abundant rare earth(RE)-based nanocrystalline multi-component(Ce,La,Y)-Fe-B alloys containing no critical RE elements of Nd,Pr,Dy,and Tb by melt-spinning technique.The roles of La and Y substitutions for Ce have been fully understood.La plays a positive role on both thermal stability and room-temperature(RT)magnetic properties.The enhanced coercivity Hcj by partial substitution of La is attributed to the increases of anisotropy field HA and the formation of continuously distributed grain boundaries resulting from the suppression of CeFe2 phase.Although Y substitution is not benefit for Hcj,both remanent polarization Jr and thermal stability have been effectively improved since Y2Fe14B shows relatively high saturation magnetization Ms and a positive temperature coefficient of HA over a certain temperature range.In addition,RE element segregation has been confirmed,La prefers to enter into the grain boundaries than Ce and Y prefers to remain in the 2∶14∶1 phase.Based on these understanding,a series of melt-spun(Ce,La,Y)-Fe-B alloys have been designed.A relatively good combination of magnetic properties with maximum energy product(BH)max=7.4 MGOe,Hcj=400 kA/m,and Jr=0.63 T has been obtained in[(Ce0.8La0.2)0.7Y0.3]17Fe78B6 alloy,together with high Curie temperature(Tc=488 K)and low temperature coefficients of remanence(α=-0.255％/K)and coercivity(β=-0.246％/K).     

La2Fe14B和Ce2Fe14B合金在快淬和热处理过程中相析出行为的比较

研究了溶体快淬三元La_2Fe_(14)B和Ce_2Fe_(14)B合金的相析出行为和磁性能,对不同快淬速度(10~50 m/s)和不同热处理温度下制备的样品进行了系统分析。结果表明,通过直接快淬,La_2Fe_(14)B合金中不能形成2∶14∶1硬磁相,而Ce_2Fe_(14)B合金可以获得2∶14∶1相。La_2Fe_(14)B合金在10m/s快淬时主要由La和α-Fe相组成,而Ce_2Fe_(14)B合金中2∶14∶1硬磁相在10m/s和20m/s快淬时析出。随着辊速的增加,非晶相逐渐增多并成为主相。在热处理过程中,La_2Fe_(14)B合金析出相以α-Fe和La相为主,并且高温下液态的富La相和α-Fe相可以共存;而Ce_2Fe_(14)B合金中先析出α-Fe,后析出2∶14∶1硬磁相,随后析出相长大。结果还表明,La_2Fe_(14)B比Ce_2Fe_(14)B有更高的非晶居里温度和更低的α-Fe相析出温度。由于硬磁相的析出,Ce_2Fe_(14)B合金可以获得较好的硬磁性能,包括一定的矫顽力。此研究对含La、Ce稀土永磁材料的生产具有一定的指导作用。     

La-Mg-Ni系A5B19超晶格负极材料相结构及电化学性能EI北大核心CSCD

感应熔炼制备La0.8-xCexMg0.2 Ni 3.8(x=0,0.1,0.3,0.5),研究Ce替代部分La对La4MgNi19超晶格负极材料相结构及电化学性能的影响。研究表明,La4MgNi19合金相由LaNi5,(La,Mg)2Ni7,(La,Mg)5Ni19(3R-Ce5Co19)相组成。加入Ce后,(La,Mg)2Ni7相消失,出现2H-Pr 5Co 19结构的(La,Mg)5Ni19相,同时随着Ce替代量的增多,(La,Mg)5Ni19相含量增多,LaNi5相随之减少,Ce加入有利于形成A5B19相,特别是形成2H-Pr5Co19结构。电化学放电容量随着x值的增加呈现先增后减趋势,x=0.1时样品的电化学放电容量380.36 mAh/g最佳。合金电极活化次数、容量保持率和倍率放电性能随着Ce含量增加而增大。H在合金中的扩散速率是影响其倍率放电性能主要因素。     

The comparison of effects of four rare earth elements additions on structures and grain sizes of Ti-44Al alloy

By vacuum arc melting, four kinds of rare earth (RE) elements, Ce, La, Nd and Gd, were added in the range from 0.05% to 0.5% (mole fraction) to binary Ti-44% Al alloy to refine its grains of structures for high ductility. Effects of RE elements on structures and grain sizes of the alloy were investigated and compared. It was observed that Ce had the strongest effect on promoting growth of columnar colonies and Gd had the weakest one, while the other RE elements obviously promoted this growth in as-cast structures of the ingots. It was seen that the four RE elements initially reacted with oxygen to form oxides in the melt, the RE aluminides occur at boundaries during heat treatment, and sometimes the aluminide co-existed with oxide at boundaries or in grains. Results of measurement of grain sizes showed that the grains in the ingots heat-treated were effectively refined by properly adding the four RE elements, and the average grain size in the ingot with 0.15% Gd is finer and more uniform than that with Ce, La and Nd. The results of comparison verified that the sequence of effects of the four RE elements is Ce, La, Nd and Gd from strong to weak, which means that the alloy is sensitive to a small amount of Ce addition and is comparatively dull to a larger amount of Gd.     

Effects of rare-earth element substitution on magnetostrictive properties of polycrystalline Tb-Dy-Fe alloys

Magnetostrictive properties of (Tb/sub 0.5/Dy/sub 0.5/)/sub 1-x/RE/sub x/Fe/sub 1.9/ (x=0-0.05, RE=Y, Ce, Sm, Gd, Ho, Yb) polycrystalline compounds were studied. Each rare-earth element formed a RE-Fe/sub 2/ Laves compound with a different lattice spacing. Corresponding to this difference, (Tb/sub 0.5/Dy/sub 0.5/)/sub 0.95/RE/sub 0.05/Fe/sub 1.9/ alloys showed a variation in lattice spacing as a result of the substitution of rare-earth elements and the prestress dependence of magnetostriction changed noticeably. In the case of Y, Sm, and Gd substitution, which showed greater lattice spacing than that of the Tb/sub 0.5/Dy/sub 0.5/Fe/sub 1.9/ alloy, the prestress dependence and maximum magnetostriction decreased. On the other hand, in the case of Ce, Ho, and Yb substitution, which showed a decrease in lattice spacing, the conspicuous prestress dependence was the same as that of the Tb/sub 0.5/Dy/sub 0.5/Fe/sub 1.9/ alloy and the maximum magnetostriction was greater than that of the latter alloy.     

Mn替代Ni对(La0.8Nd0.2)2Mg(Ni0.9-xCo0.1Mnx)9合金储氢及电化学性能的影响

在Ar保护下采用磁悬浮感应熔炼制备(La0.8Nd0.22)Mg(Ni0.9-xCo0.1Mnx)9(x=0,0.05,0.1,0.15)合金,系统研究了元素替代及退火处理对合金相结构、吸放氢性能及电化学性能的影响。结果表明,合金相主要由(La,Nd)Ni5相、LaMg2Ni9相和(La,Nd2)Ni7相组成,当x=0.15时,(La,Nd)2Ni7相消失。随着Mn取代量的增加,合金的储氢量、放电容量先增加后减小,Mn的添加提高了合金的充放电循环稳定性。经1073K退火处理后合金的放电容量得到提高,循环稳定性能得到明显改善。     

Book review

Abstract

Magnesium based Mg–9Al–1Zn–5RE (RE=Y, La, Nd, Ce, or Pr) alloys with or without an addition of 1%Si were rapidly solidified by chill block melt spinning and splat quenching. The base alloy AZ91 (Mg–9Al–1Zn) was also rapidly solidified. Isochronal heat treatment for 1 h at 100–400°C showed that the microhardness of the ribbon maintained a similar level to that of the as spun alloy up to 300°C but decreased when heat treated at 400°C. Isothermal heat treatment for up to 24 h at 250–350°C showed that there were aging responses for the sample treated at 250°C while above this temperature, the microhardness decreased as the treatment time increased. The addition of 5% of RE elements to AZ91 displaced the Mg₁₇Al₁₂ phase in AZ91 with fine dispersoids of Al₂RE (RE=Y or Nd) or Al₁₁RE₃ (RE=La, Nd, Ce, or Pr) in Mg–9Al–1Zn–5RE alloys. These Al–RE intermetallics remained fine and precipitated at the grain boundaries so restraining grain growth during heat treatment at up to 400°C. Although Mg₂Si precipitates were found to be present in the silicon containing alloys after heat treatment at 400°C, their size was greater than those of Al–RE intermetallics, indicating that Mg₂Si has a lower thermal stability than these Al–RE intermetallics. The relationship between microhardness and grain size is discussed.

MST/3400     

Effect of Heat Treatment on Microstructure and Magnetic Properties of Ce-Doped NdFeB Ribbons

The substitution for Nd by abundant element cerium (Ce) is a practical way for the comprehensive utilization of rare earth resources in NdFeB permanent magnets. In this letter, we have prepared the Ce-doped NdFeB ribbons and conventional NdFeB ribbons by melt quenching method and investigated the effects of heat treatment on the crystallization behavior, microstructure, and magnetic properties of the alloy. The results show that: (1) The crystallization behavior and the microstructural changes of the (Nd,Ce)FeB magnets are similar to the conventional NdFeB magnet when heat treatment. In addition, the Ce₂Fe₁₄B phase has a significant effect on the properties of the whole magnets. (2)The NdFeB phase and CeFeB phase are relatively close to each other after being precipitated from the amorphous phase. The coupling effect between the two phases is strong enough to weaken the effect of the addition of Ce and making the properties of the NdFeB magnets to not reduce too much after adding Ce.     

As-cast microstructures in U–Pu–Zr alloy fuel pins with 5–8 wt.% minor actinides and 0–1.5 wt% rare-earth elements

The Idaho National Laboratory (INL) is investigating U–Pu–Zr alloys with low concentrations of minor actinides (Np and Am) and rare-earth elements (La, Ce, Pr, and Nd) as possible nuclear fuels to be used to transmute minor actinides. Alloys with compositions 60U–20Pu–3Am–2Np–15Zr, 42U–30Pu–5Am–3Np–20Zr, 59U–20Pu–3Am–2Np–1RE–15Zr, 58.5U–20Pu–3Am–2Np–1.5RE–15Zr, 41U–30Pu–5Am–3Np–1RE–20Zr, and 40.5U–30Pu–5Am–3Np–1.5RE–20Zr (where numbers represent weight percents of each element and RE is a rare-earth alloy consisting of 6% La, 16% Pr, 25% Ce, and 53% Nd by weight) were arc-melted and vacuum cast as fuel pins approximately 4 mm in diameter. The as-cast pins were sectioned, polished, and examined by scanning electron microscopy. Each alloy contains high-Zr inclusions surrounded by a high-actinide matrix. Alloys with rare-earth elements also contain inclusions that are high in these elements. Within the matrix, concentrations of U and Zr vary inversely, while concentrations of Np and Pu appear approximately constant. Am occurs in the matrix and with some high-rare-earth inclusions, and occasionally as high-Am inclusions in samples without rare-earth elements.     

Microstructure and magnetic property of M-type SrRe(x)Fe(12-x)O19 by sol-gel method

Magnetoplumbite-type (M-type) SrRE(x)Fe(12-x)O19 (RE = La and Ce, x = 0-1.0) powders were prepared by a citric acid sol-gel technique and subsequent heat treatment. The crystal structure, grain size and magnetic properties were investigated by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and vibrating sample magnetometer (VSM). The XRD patterns show that SrRE(x)Fe(12-x)O19 (RE = La and Ce) are mainly hexagonal magnetic plumbite structure, and the average grain size of 30-40 nm was calculated using the Scherer's equation based on the XRD spectrum. Substitution of Fe ion by the rare earth La ion causes a significant decrease in intrinsic coercivity (Hc) and a slight decrease in saturation magnetization (Ms) as shown in the magnetization hysteresis loops. However, the Hc rises gradually in a small wave pattern with the increase of doping content of the rare earth Ce. The relation between the crystal structure and magnetic properties was also studied in this work.     

Role of lanthanum in microstructure evolution and enhanced magnetic properties of cerium-containing sintered magnets

In this study, lanthanum was applied to strip cast Ce−Fe−B alloy to improve its phase composition and microstructure. The results reveal that lanthanum doping can significantly enhance the proportion of 2 : 14 : 1 phase and improve the microstructure of Ce−Fe−B alloy. Besides, the influence of the starting alloys structure on the microstructure and magnetic properties of final multi-phases cerium-containing magnets was also systematically investigated. Compared to the multi-phases magnet without lanthanum addition, a pronounced coercivity increment could be distinguished in lanthanum-doping multi-phases magnet, which could be attributed to the finer grain size together with ideal grain boundary. In this work, the superior performance of H_cj = 701.28 kA/m B_r = 1.30 T, and (BH)_max = 313.70 kJ/m³ were obtained by blending Nd−Fe−B alloy with (La_0.35Ce_0.65)-Fe−B alloy to meet 25.0 wt.% lanthanum-cerium utilization content, suggesting that the possibility to develop high abundant rare earth permanent magnetic materials.     

Phase Evolution and Magnetic Studies of La and Refractory Metals Co-substituted α-Fe/R_2Fe_(14)B-type Nanocomposites

1. IntroductionIn last decade, two types of NdFeB nanocomposite powders, namely, or-Fe/Nd,Fe,.B['] andFe,B/Nd,Fe,.B['] t have drawn much attention of theresearcher for the bonded magnet application, because of their high remanence (B.) and high maximum energy product ((BH)...). The deficiency ofthese types of nanocomposites is their lower coercivity (tHe <8 hoe) arisen from the existence of certain amount of magnetically soft or-Fe or Fe3B phases,which might limit their application in h…     

Phase evolution and magnetic metals co-substituted studies of La and refractory co-substituted alpha i-Fe/R2Fe14B-type nanocomposites

Phase evolution and magnetic properties of (Nd0.95La0.05)(9.5 similar to 11)Febal.M2B10.5, where M=Cr, Ti, Mb, V, Mo, Zr, Hf, Ta, Mn or W, melt spun ribbons have been investigated. Almost all the alloy ribbons, except for (Nd0.95La0.05)(9.5)Fe78M2B10.5 (M=Mo and Mn), consist merely two magnetic phases, namely alpha-Fe and R2Fe14B, which display a better combination of H-i(c) and magnetic energy product. Remanence (B-r) and coercivity (H-i(c)) values in the range of 8.0 to 9.1 kG and 9.5 to 18.9 kOe, respectively, can be achieved. Among compositions studied, the Ti and W-substitutions were found to be most effective in increasing the Br and H-i(c), respectively. For a fixed refractory metal substitution, namely, M=Cr, Ti or Mb, an increase in the total rare earth concentration resulted in nanocomposites of small grain sizes and a high volume fraction of the R2Fe14B phase, leading to an increase in the magnetic properties.     

Influence of Rare-earth Elements on Mechanical Properties of Palladium

The influence of 0.1-0.6 at.-%RE additions (RE= La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb) on themechanical properties of Pd was studied. All above RE additions increased not only the strengthproperties at ambient temperature but also the tensile strength, creep rupture time and activation en-ergy at high temperatures, simultaneously increased the elongation of Pd. In the range of dilute con-centration, the strength properties of Pd-RE alloy enhanced linearly with RE concentration. Whenthe strength properties of Pd-RE alloys were normalized at 0.1 at.-%RE, it was found that light REelements had stronger effect on the properties of Pd than heavy RE, whereas Eu, Yb, Ce had anoma-lous effect. In all Pd-RF alloys, Pd-Eu alloy had the highest strength properties, successively Pd-Yband Pd-Ce alloy. The effect mechanisms of RE in alloy, such as purifying impurities, increasingrecrystallization temperature, refining grain size. expanding crystal lattice, increasing dislocation den-sity and decreasing stacking fault energy, forming stable RE oxidation by internal oxidation, and soon, were observed. They were strengthening sensitive factors. The influence of the factors onstrength properties and elongation of Pd was discussed.     

Explaining texture weakening and improved formability in magnesium rare earth alloys

Wrought magnesium alloys are rarely used due to their poor formability which is caused by strong textures created during processing. Addition of rare earth (RE) elements including Y, Ce, La, Gd and Nd weakens these strong basal textures and significantly improves formability. Developing a mechanistic understanding of this effect is critical in leading alloy design towards a new class of highly formable magnesium alloys. This fall in texture intensity occurs during recrystallisation and only requires very low solute RE additions, 0·01 at.-% in the magnesium–Ce case. These additions retard dynamic recrystallisation and increase non-basal slip; however, a full understanding of the RE effect has yet to be obtained, with a variety of mechanisms proposed. Recent research in these areas is critically reviewed.     

Glass-Forming Ability for Nd70-xFe20AlioYx and Nd60-xFe30Al10Yx Alloys

The glass-forming ability (FGA) of Nd70-xFe20Al10Yx and Nd60-xFe30Al10Yx(0≤x≤15) alloys produced by Cu mold casting was investigated.Except Y=5 at.pct,bulk amorphous Nd70-xFe20Al10Yx alloys up to 2mm in diameter were obtained.The GFA for Nd60-xFe30Al10Yx alloys,however,was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy.The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3mmm in diameter.The melting temperature or /and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys.The bulk amorphous c ylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization.The crystallization temperature,Tg,and the supercooled liquid region,ΔTx,are 776K and 58K,respectively,The GFA and thermal stability of the Nd-Fe-Al-Y alloys were discussed.     

Effect of addition of elements on two-glass-forming ability of Zr–Ce–Co–Cu immiscible alloys

The effects of Al element addition and partial substitution of Ce with La, Pr, and Nd on the two-glass-forming ability of the phase-separating Zr–Ce–Co–Cu alloy system have been studied. The distribution of the additions in the two coexistent immiscible liquids was analysed thermodynamically. The results indicate that Al almost equally distributes in the two liquids, whereas the elements La, Pr, and Nd are predominantly found in the Ce–Cu-rich liquid. X-ray diffraction analysis reveals that these additions obviously enhance the two-glass-forming ability of the coexisting liquids. This work presents a strategy for improving the two-glass-forming ability of immiscible alloys to obtain phase-separated bulk metallic glasses.     

ICP—AES法测定稀土—铁—镁合金的成分

本文叙述了用 ICP—AES 法同时测定稀土—铁—镁合金中各元素含量。研究了高含量Fe 对其他元素测定的影响。三个标样的测定结果表明该方法是准确可靠的。     

Research and development of Ce-containing Nd_2Fe_(14)B-type alloys and permanent magnetic materials

Much demanded and overused are the critical rare-earth elements such as Pr, Nd, Dy, and Tb with increasing need of Nd Fe B-type rare-earth permanent magnets in the enlarging application areas, developing new high-tech industries, and emerging cutting-age frontiers. The balance and efficient use of rare-earth resources comes into being the national strategy, national defense, and border safety for many major countries and regions in the world.(Nd,Ce)Fe B-based permanent magnetic materials, which can not only reduce cost but also offer a feasible way for integrated and effective utilization of rare earth resources,have received much attention in recent years. The existence of CeFe_2 and the mixed valence state of Ce in Ce Fe B compound, the different metallurgy behavior and the particular processing as well as potential various magnetic-hardening mechanisms, however, make it quite different from Nd-based alloys.For instance, the coercivity of Ce-containing magnets in some certain composition range, is even higher than that of the counterpart pure Nd-based magnets though the Ce-containing magnets possess inferior intrinsic properties. Consequently, it is very important to design proper composition and structure, optimize processing, and analyze the mechanisms in depth for this kind of magnet. High performance and cost-effective magnets can be fabricated if we can make full use of the composition's inhomogeneous and abnormal coercivity variation of the Ce-containing permanent magnets. In this paper, we have summarized the phase structures, magnetic properties and microstructures of(Nd,Ce)Fe B-based permanent magnetic materials to shed light on further research and development of this type of so-called "gap magnet".     

Magnetic properties of melt spun mischmetals-Fe-Ti-B nanocomposite ribbons

Magnetic properties and phase evolution of melt spun R9.5Fe(bal.)Ti2B10 (R = MM(A), MM(B), MM(C), Pr, Nd, Ce, and La) nanocomposites have been investigated. Based on the results for the X-ray diffraction and thermal magnetic analysis, only 2:14:1 and alpha-Fe phases appear for R = MM(A) and Pr, and an additional Fe3B phase is present for R = MM(B), MM(C), Nd, and Ce. Besides, the uniform fine grain size of 20-40 nm is almost unchanged for the ribbons with various rare earth elements. Accordingly, magnetic properties of MM9.5Fe(bal.)Ti2B10 nanocomposites are mainly dominated by the composition of Mischmetals or the rare earth elements adopted, and are consistent with the outcome for the combinations of magnetic properties of their corresponding R9.5Fe(bal.)Ti2B10 nanocomposites. In this study, the optimum magnetic properties of B(r) = 9.3 kG, (i)H(c) = 12.1 kOe and (BH)(max) = 18.0 MGOe can be achieved for MM(B)9.5Fe(bal.)Ti2B10 nanocomposites. They not only exhibit comparable magnetic properties to the commercial available powders but also reduce the original material cost effectively.