Phase Equilibria of the Al–V–RE (RE?=?Gd, Ho) Systems at 773?K (500?°C)

Isothermal section of the Al–V–RE (RE = Gd, Ho) ternary systems at 773 K (500 °C) was investigated over the whole concentration range by means of X-ray diffraction and scanning electron microscopy equipped with energy dispersive X-ray analysis. The crystal structures of the Al₄₃Mo₄Ho₆-type ternary compounds Al₄₃V₄RE₆ were determined with Rietveld refinement method. The intermetallic compound Al₄₃V₄Gd₆ belongs to the Space group P6₃/mcm, with cell parameters of a = b = 1.0996(6) nm, c = 1.7813(9) nm, α = β = 90 deg, γ = 120 deg, and volume of unit cell of 1.8658(9) nm³. At 773 K (500 °C), all the Al-rich ternary alumides, i.e., Al₄₃V₄Gd₆, Al₂₀V₂Gd, Al₄₃V₄Ho₆, and Al₂₀V₂Ho appear without any significant homogeneity region. Five binary compounds, i.e., AlV₃, Al₄Gd, Al₁₇Gd₂, Al₁₇Ho₂, and AlHo₂ reported in the literature were not found. Fifteen and 14 ternary phase fields have been identified in the isothermal section of the Al–V–Gd and Al–V–Ho ternary systems, respectively. The solid solubility of V in Al₂RE₃, AlRE, and Al₂RE amounts to approximately 1.0 at. pct to 2.0 at. pct, whereas the solid solubility of Al in V is approximately 39 at. pct.     

Coercivity kinetics upon step annealing of sintered Sm(Co_(0.88-x)Fe_xCu_(0.09)Zr_(0.03))_7 magnets

Behavior of the coercivity of the high-temperature Sm(Co_(0.88-x)Fe_xCu_(0.09)Zr_(0.03))_7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo_5 phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm_2 Co_(17) and SmCo_5 phases.Diffusive enrichment of the SmCo_5 phase in Cu close to the interface with Sm_2 Co_(17) leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.     

Influence of Fe Content on Microstructure and Magnetic Properties of Melt-Spun SmCo-Based Alloy Ribbons

The microstructure and magnetic properties of melt-spun Sm(Co_0.88-xFe_xCu_0.10Zr_0.02)_7.5 (x = 0.1 and 0.2) alloy ribbons have been studied. The results showed that the as-spun ribbons were in a single phase, SmCo₇, with the Cu₇Tb structure. When aged in the temperature range from 720 to 900 °C, the SmCo₇ phase transformed into Sm₂Co₁₇, SmCo₅, and CoFe(Zr) phases with a minor Sm₂Co₃ phase. For the x = 0.1 alloy, a large coercivity, H_c = 8.7 kOe, was observed although the soft magnetic CoFe(Zr) phase was present in the alloy. The volume fraction of the CoFe(Zr) phase increased when the ageing temperature increased from 720 to 760 °C. At higher ageing temperature, the CoFe(Zr) phase was partially re-dissolved. With an increase in the Fe content in the alloy, the CoFe(Zr) phase increased significantly, causing the coercivity to decrease.     

Magnetic property and microstructure of SmCo magnetic recording films

Cr/SmCo/Cr thin films with Sm concentration of 37.7 at.% were deposited on glass substrates by magnetron sputtering. Meas-urement of magnetic properties showed that the SmCo film possessed good magnetic anisotropy, a high coercivity of 3019 kA/m and low magnetic exchange coupling. Microstructure analysis showed that crystallized SmCo5 magnetic phase, non-magnetic SmCo2 phase and Sm2Co7 phase co-existed ill the film. The non-magnetic SmCo2 phase might function as isolator of SmCo grains, leading to a decrease of magnetic exchange coupling. Moreover, a Cr2)3 oxide layer which could protect the SmCo layer from oxidation formed at the surface of the Cr cap layer.     

Morphology and magnetic properties of Sm2Co7/α-Fe nanocomposite magnets produced by high energy ball milling and spark plasma sintering

In this article,the Sm₂Co₇/α-Fe nanocomposite magnets were prepared by high energy ball milling and spark plasma sintering method.The effect of soft phase content on the magnetic properties was studied.Up to 30 wt% α-Fe was added into Sm₂Co₇ matrix without the decrease of remanence.Optimal energy product(BH)max of 9.2 MGOe was obtained with 20 wt% α-Fe.TEM observation shows that the grain size of α-Fe is 20-50 nm which ensures a good coupling effect between soft and hard phase.One more thing needs to be mentioned is that there exists inter-diffusion between Sm-Co phase and α-Fe phase.Moreover,our results can also illustrate that the Sm₂Co₇/α-Fe nanocomposite magnets are able to acquire better magnetic properties than the SmCo₅/α-Fe magnets prepared by the same process due to the large domain width of Sm₂Co₇ phase.     

Samarium solubility in an yttrium- and gadolinium-containing magnesium-based solid solution

Metallographic, X-ray diffraction, and electron microprobe analyses and electrical resistivity measurements are used to study the samarium solubility in a magnesium-based solid solution containing equal fractions of yttrium and gadolinium at 500, 400, and 300°C. The regions of existence of the magnesium-based solid solution at these temperatures and the phases in equilibrium with this solid solution are determined. The magnesium solid solution is found to be in equilibrium only with the Mg₄₁Sm₅ and Mg₂₄(Y, Gd)₅ phases, which belong to the binary Mg-Sm and Mg-Y-Gd systems, respectively. These results are used to construct isothermal sections of the Mg-Y-Gd-Sm phase diagram at 500, 400, and 300°C and equal yttrium and gadolinium contents in the region adjacent to the magnesium solid solution.     

Promotional effects of samarium on Co3O4 spinel for CO and CH4 oxidation

A series of Co3O4 spinel catalysts modified by Sm were prepared by co-precipitation method and tested for CH4 and CO oxidation.The addition of a small amount of Sm into Co3O4 led to an improvement in the catalytic activity for both reactions.Co0.98Sm0.02 and Co0.95Sm0.05,the two samples with Co/Sm molar ratio of 0.98/0.02 and 0.95/0.05 in sequence,showed the similar and the highest activity for CH4 oxidation,with CH4 complete conversion at 450 oC.In contrast,Co0.90Sm0.10 was the most active sample for CO oxidation,with CO complete conversion at 120 oC.The catalysts were characterized by techniques of N2 adsortion-desorption with Brunauer-Emmett-Teller technique(N2-BET),X-ray powder diffraction(XRD),thermal gravity analysis-differential scanning calorimetry(TGA-DSC),H2 temperature programmed reduction(H2-TPR) and X-ray photoelectron spectroscopy analysis(XPS).Compared with pure Co3O4,for Co1–x Smx catalysts with 0.02≤x≤0.10,the addition of a small amount of Sm resulted in the formation of spinel Co3O4 and amorphous SmCoO3,hence increasing the number of Co3+ and the active surface oxygen species,which was responsible for the improvement of the activity.Co0.95Sm0.05 catalyst showed not only high thermal stability and activity but also good reaction durability in the presence of 5% water vapor for CH4 oxidation.     

Phase Diagrams of the Zr–Si–RE (RE=La and Er) Ternary Systems at 773?K (500?°C)

The isothermal sections of the phase diagram of the Zr–Si–RE (RE=La and Er) systems at 773 K (500 °C) have been investigated using X-ray power diffraction (XRD), scanning electron microscopy (SEM), and optical microscopy (OM) with the aid of metallographic analysis. The existences of 10 binary compounds, namely ZrSi₂, α-ZrSi, α-Zr₅Si₄, Zr₃Si₂, Zr₂Si, RESi₂, RESi_2–x , RESi, RE₅Si₄, and RE₅Si₃ have been confirmed in the Zr–Si–RE (RE=La and Er) systems, respectively. As for the reported binary compound RE₃Si₂, only La₃Si₂ has been observed in the Zr–Si–La system, whereas Er₃Si₂ was not found. No binary compound was found in the Zr–RE binary systems, and no ternary compound was found in the current ternary systems. None of the phases in Zr–Si–La system reveals a remarkable solid solution at 773 K (500 °C). However, the maximum solid solubility of Zr in Er, Er₅Si₃, Er₅Si₄, ErSi, ErSi_1.67, and ErSi₂ is determined to be approximately 12.0 at. pct, 2.4 at. pct, 3.0 at. pct, 3.3 at. pct, 2.2 at. pct, and 1.8 at. pct, respectively. The maximum solid solubility of Er in ErSi₂ is approximately 1.8 at. pct. No remarkable solid solubility of the elements in any of the other phases has been observed.     

Effect of heat treatment on phase and structural transformation in SmCo5 alloy powder

Conclusions The temperature range of precipitation of the Sm₂Co₁₇ phase in a single-phase SmCo₅ powder is 600–650 °C. The formation of the Sm₂Co₁₇ phase as a result of phase separation substantially decreases the degree of texturization acquired by a powder in a magnetic field. The recrystallization temperature of SmCo₅ powder lies in the range 450–500°C.Translated from Poroshkovaya Metallurgiya, No. 7(211), pp. 70–74, July, 1980.     

Effect of time of sintering on some properties of SmCo5 magnets

Conclusions A study was made of the effect of time of sintering at 1120–1170°C on the magnetic characteristics of SmCo₅ magnets. It was established that the specific magnetization intensity and coercive force of these magnets change appreciably at the beginning of sintering (_s < 5 min), but subsequently vary but little with sintering time. The presence of a low-meltingpoint addition was found to have no effect on the densification rate of SmCo₅ powder compacts. The sintering of SmCo₅ magnets of optimum chemical composition occurs in the solid state irrespective of the method by which the SmCo₅ powder has been enriched in samarium. It is proposed that a Sm₂Co₇ alloy powder be employed for this purpose. Structural equilibrium in particles, which is chiefly responsible for the magnetic characteristics of sintered SmCO₅ specimens, becomes established in a short period of time thanks to a high value of coefficient of diffusion.Translated from Poroshkovaya Metallurgiya, No. 3(183), pp. 70–75, March, 1978.     

Effect of Al82.8Cu17Fe0.2 alloy doping on structure and magnetic properties of SmCo5-based ribbons

This work tries to improve the magnetic properties by multi-element doping in the form of a ternary alloy.SmCo₅₊χwt%Al-Cu-Fe(x=0-7)ribbons melt-spun at 40 m/s were produced by adding Al_82.8Cu₁₇Fe_0.2alloy into SmCo₅ matrix,and their phases,microstructure,and magnetic properties were investigated.The results show that both x=0 and 3 ribbons form a cellular microstructure.Al-Cu-Fe addition reduces the content of the Sm₂(Co,M)₇ cell wall,narrows its width,and forms the local disordered micro-regions and solute-segregation nanoclusters in the Sm(Co,M)₅ grains.With x increasing to5,Al-Cu-Fe addition promotes the phase separation between and within grains of the SmCo₅-based alloy.The Al-Cu-Fe addition can simultaneously improve the coercivity and magnetization of the SmCo₅-based ribbons,in particular,the magnetization of the x=3 ribbons increases by 35%,while the coercivity of the x=5 ribbons increases by 3.9 times.Finally,the microstructure evolution models are built up,and the relationship between the microstructure and the magnetic properties is discussed.     

Phase Equilibria of Sn-Co-Cu Ternary System

Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys?? development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523?K, 1073?K, and 1273?K (250?°C, 800?°C, and 1000?°C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn₃Co₂Cu₈, was found. The solubilities of Cu in the ??-CoSn₃ and CoSn₂ phases at 523?K (250?°C) are 4.2 and 1.6?at. pct, respectively, while the Cu solubility in the ??-Co₃Sn₂ phase is as high as 20.0?at. pct. The Cu solubility increases with temperature and is around 30.0?at. pct in the ??-Co₃Sn_2?at 1073?K (800?°C). The Co solubility in the ??-Cu₆Sn₅ phase is also significant and is 15.5?at. pct at 523?K (250?°C).     

Isothermal Section of Er-Mn-Nd Ternary System at 773 K

The isothermal section of the Er-Mn-Nd ternary system at 773 K was investigated mainly by X-ray powder diffraction with the aid of differential thermal analysis. The 773 K isothermal section of the ternary system consists of 9 single-phase regions, 14 two-phase regions, and 6 three-phase regions. At 773 K, the maximum solid solubility of Er in Nd and Nd in Er is about 20%（atom fraction） Er and 26%（atom fraction） Nd, respectively. Er6Mn23 and Nd6Mn23 form a continuous solid solution. The homogeneity range of δ phase extends from about 38% （atom fraction） Er to 43% （atom fraction） Er. No ternary compounds were observed at 773 K in this system.     

Fabrication of SmCo_5 alloy via cobalt-induced calciothermic reduction and magnetic properties of its ribbon

SmCo_5 alloy was prepared via direct calciothermic reduction using anhydrous samarium fluoride(SmF_3)as raw material and cobalt as inducer.Results of the thermodynamic calculation show that the direct reduction of cobalt-induced SmF_3 for preparing SmCo_5 alloy is feasible.An alloy with 33.89 wt%samarium and a yield of 96.45% were achieved under the optimal conditions of 10% and 20% excess of SmF_3 and calcium over the stoichiometry,respectively,and 1450℃ for 4 min.The X-ray diffraction results show that the reduction products are SmCo_5 alloy and CaF_2.The scanning electron microscopy micrograph of the SmCo_5 alloy ingot exhibits a distinct dendritic morphology composed of samarium and cobalt.The X-ray photoelectron spectroscopy shows that the atomic ratio of samarium to cobalt is approximately 1:5 and both elements demonstrate zero valency(Sm~0,Co~0).The magnetic properties measurement of the SmCo_5 alloy melt-spun ribbon shows the remanent magnetization B_r=0.59 T,intrinsic coercivity H_(Ci)=345.82 kA/m and maximum magnetic energy density(BH)_(max)=42.20 kJ/m~3.These results may be helpful for the development of novel valence-variable rare-earth alloys.     

Luminescence properties of phosphate phosphors Ba3Gd1−x(PO4)3:xSm3+

A series of reddish orange phosphors Ba_3Gd_(1-x)(PO_4)_3:xSm~(3+)(x = 0.02.0.04,...,0.12) were prepared by the high-temperature solid-state reaction. X-ray powder diffraction(XRD) and diffuse reflectance and photoluminescence spectra were utilized to characterize the structure and spectral properties of the phosphors. The phosphors have strong absorption in the near-UV region. CIE chromaticity coordinates of the phosphors are located in the reddish orange region since the strongest emission band is around 598 nm and related to the ~4 G_(5/2)→~6 H_(7/2) transition of Sm~(3+). Optimal concentration of Sm~(3+) in the phosphors is about 6.0 at%. The quantum yield of the Ba_3Gd_(0.94)(PO_4)_3:0,06 Sm~(3+) under excitation at 403 nm is about 52.07%. Temperature dependent photoluminescence spectra of the Ba_3Gd_(0.94)(PO_4)_3:0.06 Sm~(3+) were measured and the phosphor exhibits high thermal stability of emission. All the results show that the Ba_3Gd(PO_4)_3:Sm~(3+) phosphor may be a potential red phosphor for near-UV based white LEDs.     

Joint solubility of samarium and dysprosium in solid magnesium

The phase compositions of solid Mg–Sm–Dy alloys corresponding to the magnesium-corner region of the phase diagram are studied by optical and scanning electron microscopy, electrical resistivity measurements, and electron microprobe analysis. The obtained results allowed us to determine the joint solubility of samarium and dysprosium in solid magnesium at 500, 400, and 300°C; it decreases with decreasing temperature. The magnesium solid solution is found to be in equilibrium only with the Mg₄₁Sm₅ and Mg₂₄Dy₅ compounds, which are in equilibrium with the magnesium solid solution in the binary Mg–Sm and Mg–Dy systems.     

Preparation of Sm2O3 and Co3O4 from SmCo magnet swarf by hydrometallurgical processing in chloride media

The recycling of rare earth elements(REE) from end-of-life REE based products is an environment friendly proposition. Waste Sm-Co based permanent magnet generated during machining is a good source for both Sm and Co. In the present study a simpler process of acid leaching at 80 ℃ followed by solvent extraction, oxalate precipitation and calcination is described for producing pure Sm_2 O_3 and Co_3 O_4. With either 10 vol% H_2SO_4 or 15 vol% HCI at 80 ℃ more than 95% Sm and Co are leached in 1 h.Extraction of Sm from sulphate leach liquor with TBP or Aliquat 336 was poor. Although extraction with TOPS-99 is quantitative but Sm from sulphate leach liquor precipitated as Sm_2(SO_4)_3·8 H_2 O. The chloride leach liquor at an initial pH of 2.5 and with 1.2 mol/L TOPS-99 shows requirement of 4-stages at A:O = 3:2. Stripping with oxalic acid precipitates Sm-oxalate which is calcined at 800 ℃ to produce Sm_2 O_3. Co_3 O_4 is recovered from the raffinate through oxalate precipitation followed by calcination at450℃.     

Phase Equilibria of the Cu-Ti-Er System at 773?K (500?°C) and Stability of the CuTi3 Phase

The phase relationships of the Cu-Ti-Er ternary phase diagram at 773?K (500?°C) were investigated mainly by means of X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), and differential thermal analysis (DTA). It is confirmed in this work that the binary compounds Cu₉Er₂ and Cu₇Er₂ exist in the Cu-Er binary system at 773?K (500?°C). The stability of the CuTi₃ phase is confirmed in the Cu-Ti system. After heat treatment at 1023?K (750?°C) for 90 hours, the phase CuTi₃ is observed in the microstructure of the alloy 25Cu75Ti. The temperature of the eutectoid transformation, namely, ??-Ti ? ??-Ti?+?CuTi₃, is determined to be 1078?K (805?°C) in this work. The 773?K (500?°C) isothermal section consists of 14 single-phase regions, 25 two-phase regions, and 12 three-phase regions. None of the phases in this system reveals a remarkable homogeneity range at 773?K (500?°C).     

Phase diagram of Er-Sn-Te system for diluted magnetic semiconductor developments

Phase diagrams of the RE (rare earth)-IV-VI systems are very important for the design of rare earth doped diluted magnetic semiconductors (DMSs), but related information is very limited. In this work, ...     

Alloying behavior of Co3Ti

The alloying (substitution) behavior of Ll₂-type Co₃Ti({fx1433-01}) compound was investigated at an isothermal section of 1323 K by the observation of the direction of solubility lobe of Ll₂ phase. The solubility lobes of additions of V, Ta, Cr, W, and Al indicated that they substitute for Ti site, those of Ni and Cu for Co site, and that of Fe for both sites. However, the preferable substitution natures for additions of Zr, Hf, Nb, Mn, and Si, and of Mo and Ge were not determined because of the small solubility limit, and because of no preferable solubility lobe, respectively. The substitution behavior and solubility limit obtained in the ternary Co₃Ti compound were evaluated with the thermo-dynamic concept. The Research Institute for Iron, Steel and Other Metals The Research Institute for Iron, Steel and Other Metals