Solubility Of Gd Research Articles

Section dimension induced microstructure and mechanical properties variations of sequential solidified sand–cast Mg–10Gd–0.2La–0.1Zn–0.4Zr (wt%) alloy

Casting dimension significantly influences the quality and performance of finished products when employing a sequential solidification process. Tapered cylinder Mg–10Gd–0.2La–0.1Zn–0.4Zr (wt%) castings with variable section dimensions were fabricated by sand–cast process, and the role of section dimension on the solidification behavior, microstructures and mechanical properties under different thermal conditions were systematically investigated. Increasing section dimension from Φ23 mm to Φ32 mm, the average cooling rate during solidification decreases from 1.70 °C/s to 0.86 °C/s, and the actual chemical composition of Gd element descends from 10.39 ± 0.11 wt% to 10.05 ± 0.06 wt%. Meanwhile, the primary α–Mg grains are coarsened in size from 29 ± 2 μm to 39 ± 3 μm, and the area ratio of the secondary phase degrades from 1.87 ± 0.19 % to 1.14 ± 0.31 %. With a solution treatment of 500 °C × 8 h, the area ratio of the residual secondary phase rises from 0.55 ± 0.06 % to 0.75 ± 0.12 %, accompanied by the decrease of Gd solubility with a grand value of 0.33 wt%. The decline of Gd solubility is unfavorable for the precipitation of strengthening phases during the ageing treatment and leads to a reduction of ∼13.5% in the area number density of the β′ precipitates. The strength and ductility at ambient temperature simultaneously worsen with increasing section dimension, in which the yield strength, ultimate tensile strength and elongation respectively descend from 230 ± 7 MPa, 364 ± 7 MPa and 8.5 ± 1.1 % to 219 ± 6 MPa, 336 ± 5 MPa and 5.5 ± 0.9 % in the peak–aged condition. The strength debasement is due to the grain coarsening and lower number density of the β’ precipitates, while the reduced ductility is attributed to the coarser grains and higher content of the residual secondary phase with larger size. Casting dimensions should be meticulously designed when developing high–performance Mg alloys by sequential solidification processes.

Measurement of liquidus in metal-rich region of lanthanoid-oxygen binary systems and the thermodynamic evaluation

In this study, the solubilities of oxygen in molten La, Gd, Tb, Ho, and Er metals were measured and the oxide phases in equilibrium with each of these lanthanoid metals were identified to systematically determine the liquidus of lanthanoid-oxygen systems in the metal-rich region. The molten lanthanoid metal and lanthanoid oxide pellets were equilibrated at 1573–1873 K and then quenched. The oxygen concentration in the quenched metals was measured using inert gas fusion infrared absorption spectroscopy to determine the oxygen solubilities of molten lanthanoid metals. The crystal structures of the quenched lanthanoid oxide pellets were analyzed using XRD to identify the equilibrium oxide phases, which were identified as the sesquioxides of each lanthanoid element. Furthermore, the Gibbs free energies of the liquid phases of the Ln-O (Ln = La, Pr, Gd, Tb, Dy, Ho, Er) systems were evaluated using the CALPHAD method and thermodynamic software Pandat based on the oxygen solubilities of molten La, Gd, Tb, Ho, and Er metals measured in this study and those of Pr and Dy reported in previous studies.

Achieving superior elevated-temperature strength of Mg-12Gd-3Y alloys by Nd addition

There is a tremendous demand for heat-resistant Mg alloys in aerospace and automotive applications. In this paper, different Nd contents are added to Mg-12Gd-3Y alloy to design the joint action of multiple rare earth (RE) elements to improve the elevated-temperature (ET) strength. The Mg-12Gd-3Y-1.0Nd alloy after extrusion and aging (E-A) process showed excellent strength and toughness matching at room temperature (RT), 200 °C, and 250 °C. The E-Aed Mg-12Gd-3Y-1.0Nd alloy showed ultimate tensile strength (UTS), tensile yield strength (TYS), and elongation (EL) of 440 MPa, 312 MPa, and 6.2% at RT. The E-Aed Mg-12Gd-3Y-1.0Nd alloy showed UTS, TYS, and EL of 405 MPa, 306 MPa, and 12.6% at 200 °C. The E-Aed Mg-12Gd-3Y-1.0Nd alloy showed UTS, TYS, and EL of 382 MPa, 303 MPa, and 19.4% at 250 °C. The addition of Nd elements reduces the solid solubility of Gd, and Y in the Mg matrix, thus precipitating many Mg5RE and β′ phases in the alloy. The excellent mechanical properties of Mg-12Gd-3Y-1.0Nd alloy after E-A treatment come from the fine grain size, segregation at grain boundaries (GBs), and delicate dispersed second phases. The fine grain size is beneficial to inhibit crack expansion, allowing it to consume more energy during the expansion process and improve strength. Both grain boundary segregation and diffusely distributed second phase can effectively inhibit grain boundary sliding and enhance strength.

Determination of the distribution of rare earth elements La and Gd in Daphnia magna via micro and nano-SXRF imaging.

While our awareness of the toxicity of rare earth elements to aquatic organisms increases, our understanding of their direct interaction and accumulation remains limited. This study describes the acute toxicity of lanthanum (La) and gadolinium (Gd) in Daphnia magna neonates and discusses potential modes of action on the basis of the respective patterns of biodistribution. Ecotoxicological bioassays for acute toxicity were conducted and dissolved metal concentrations at the end of the tests were determined. The results showed a significant difference in nominal EC50 (immobility) between La (>30 mg L-1) and Gd (13.93 (10.92 to 17.38) mg L-1). Daphnids that were then exposed to a concentration close to the determined EC50 of Gd (15 mg L-1, nominal concentration) for 48 h and 72 h were studied by synchrotron micro and nano-X-ray fluorescence to evaluate the biodistribution of potentially accumulated metals. X-ray fluorescence analyses showed that La was mainly found in the intestinal track and appeared to accumulate in the hindgut. This accumulation might be explained by the ingestion of solid La precipitates formed in the media. In contrast, Gd could only be detected in a small amount, if at all, in the intestinal tract, but was present at a much higher concentration in the tissues and became more pronounced with longer exposure time. The solubility of Gd is higher in the media used, leading to higher dissolved concentrations and uptake into tissue in ionic form via common metal transporting proteins. By studying La and Gd biodistribution in D. magna after an acute exposure, the present study has demonstrated that different uptake pathways of solid and dissolved metal species may lead to different accumulation patterns and toxicity.

Influence of hydrogenation on the structural, optical and magnetic properties of Gd-incorporated WO3 nanocomposites synthesised by precipitation method

ABSTRACT Nanoparticlesof tungsten oxide combined with varying amounts of gadolinium ions were synthesised by a hydrochloric acid-assisted precipitation method. The powders were characterised by ; X-ray fluorescence (XRF), X-ray diffraction (XRD), diffuse reflectance (DRS), and magnetic measurements. The ordinary monoclinic structure of WO3 was transformed into one of its Magneli structures (W32O84) by the incorporation of a tiny Gd ions due to the variation in the local charge neutrality . Different magnetic behaviours of Gd-incorporated W-oxide were observed depending on the synthesis procedure including a hydrogenation. The hydrogenated Gd-incorporated W-oxide has FM-behaviour. However, the created FM properties were severely undermined by increasing the Gd inclusion to more than 1%, which was attributed to the effect of the Gd interionic separations and the minute solubility of Gd in of W-oxide. This study focuses on the conditions necessary to realise the creation of FM in W-oxide by Gd ions incorporation for many applications, such as optical phosphors and catalysts.

Raising the solubility of Gd yields superior thermoelectric performance in n-type PbSe

The highly electronegative halogen element Br can promote the dissolution of high-melting Gd in PbSe, thereby enhancing its band modification effect, leading to a realization of high thermoelectric performance for n-type Pb0.997Gd0.003Br0.003Se0.997.

Thermodynamic properties of Gd-Bi alloys determined by emf measurements in LiCl-KCl-GdCl3 electrolyte

Thermodynamic properties of binary Gd-Bi alloys (mole fraction, xGd = 0.02–0.35) were determined using electromotive force (emf) measurements in molten LiCl-KCl-GdCl3 electrolyte in complement with structural, microstructural, and thermal characterization. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) identified the phase constituents of Gd-Bi alloys (xGd = 0.02–0.35) as Bi matrix and GdBi compound. According to differential scanning calorimetry (DSC) measurements up to 1250 K, a eutectic transition [L = Bi + GdBi] was observed at 543 K but the reported peritectic transition [L + GdBi = GdBi2] was not detected, suggesting the absence of the GdBi2 compound. Based on structural, microstructural, and thermal characterization of Gd-Bi alloys (xGd = 0.02–0.35), the GdBi2 compound was not detected, and its thermodynamic stability is questionable. The emf of Gd-Bi alloy (xGd = 0.16) at 700–1048 K relative to Gd(s) was measured by electrodepositing pure Gd metal at 25 K increments. The emf values of Gd-Bi alloys were determined via coulometric titration of Gd into liquid Bi using a two-phase [L + GdBi] alloy as a reference electrode at 773–973 K. The solubility of Gd in liquid Bi was also estimated to be 0.50 mol% (773 K), 0.99 mol% (873 K), and 2.21 mol% (973 K) and the excess partial molar Gibbs energy (∆G̅Gdex) of liquid Gd-Bi alloys was as low as 65 kJ mol–1, indicating strong chemical interactions between Gd and Bi.

Mechanical behaviors of extruded Mg alloys with high Gd and Nd content

The influence of alloying elements and heat treatment on the microstructure and mechanical behaviors of extruded Mg–Gd–Nd ternary alloys was investigated in this study. The grain sizes dramatically decreased after extrusion, and the particles which distributed in Mg matrix had great effect on the grain size. The grain sizes of extruded alloys decreased from 26 to 5 ​μm with the alloying content increasing. The mechanical test results show that both Gd and Nd had positive effect on the hardness, yield strength and Young's modulus. The ultimate tensile strength (UTS) was enhanced by Gd content, decreased with Nd content. The elongation of alloys was lower with higher alloying elements. Those extruded alloys were aged for 200 ​h in 200 ​°C. The Young's moduli were decreased by ageing treatment. Combined with microstructure study, the part of the reinforcement which identified as Mg5(Gd/Nd) was dissolved in Mg matrix. Nd element obviously has influence on the solubility of Gd in Mg alloys.

Phase relationship in the Mg-rich corner of the Mg-Zn-Gd ternary system at 400–475 °C

Phase relationship in the Mg-rich corner at 400–475 °C of the Mg-Zn-Gd ternary system has been investigated in detail by using electron probe microanalysis (EPMA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) measurements. At 400 °C, the Z, I, F, and W phases are all in equilibrium with α-Mg. When the temperature rises to 440 °C, the Z and I phases are no longer in equilibrium with α-Mg. Only the W phase can coexist with α-Mg when the temperature reaches 475 °C. The four-phase peritectic eutectic transformations F+liquid → α-Mg+I and W+liquid → α-Mg+F occur at 427.5 °C and 448 °C, respectively. The compositions of the Z, I, F, and W phases are Mg-(64.2–64.3 at%)Zn-(7.4–8.0 at%)Gd, Mg-(57.9–58.7 at%)Zn-(8.7–9.1 at%)Gd, Mg-(59.8–63.4 at%)Zn-(13.8–14.4 at%)Gd, and Mg-(49.7–50.7 at%)Zn-(24.2–25.5 at%)Gd, respectively. The solubility of Gd in the α-Mg solid solution is dramatically decreased by the addition of Zn when the Z, I, F, W/α-Mg phases are in equilibrium, quite different from the case of Mg-Gd binary system.

Doped Ceria Nanoparticles with Reduced Solubility and Improved Peroxide Decomposition Activity for PEM Fuel Cells

Ceria nanoparticles (NPs) have unique catalytic properties which make them suited to scavenge degrading radical species and their precursor peroxides during PEM fuel cell operation. However, in the acidic environment of the fuel cell, ceria dissolves and the resulting cations migrate within the MEA, causing performance and durability losses. In this work, ex situ testing was used to evaluate the peroxide decomposition, selectivity towards radical generation, and solubility of Gd, Pr, and Zr-doped ceria NPs over a range of crystallite sizes and dopant levels. These doped materials exhibit better peroxide scavenging activity and dissolution resistance than undoped ceria. In these materials, activity is largely governed by increased surface area due to high internal porosity at smaller crystallite sizes compared to undoped ceria. Of the compounds tested, ceria NPs doped with 15 at% Zr (10 nm) and 5 at% Pr (17 nm) exhibited greater dissolution resistance than undoped ceria. Stabilization of the former doped NPs is attributed to crystallite agglomeration, while the increased stability of the latter is proposed to be due to its internally-porous, mesoscale structure suggested by its sorption isotherm. Both materials are more dissolution-resistant and active peroxide decomposers compared to undoped ceria but exhibit increased byproduct radical generation.

Phase Equilibria of the Mg-Gd-Ce System at 500 °C

The phase equilibria of the Mg-Gd-Ce system at 500 °C were investigated by means of the electron probe microanalysis (EPMA) and x-ray diffraction (XRD) on equilibrated alloys. The existence of the so-called normal tetragonal CeMg12(I) and long-range ordered CeMg12(II) was confirmed in the present work. The following five three-phase equilibria were well determined: (1) (Mg) + CeMg12(I) + Ce5Mg41, (2) (Mg) + Ce5Mg41 + GdMg5, (3) Ce5Mg41 + GdMg5 + (Ce,Gd)Mg3, (4) (Ce,Gd)Mg3 + GdMg2 + (Ce,Gd)Mg and (5) (Ce,Gd)Mg + (δCe) + (βCe). The solubility of Ce in GdMg5 and in GdMg2 was measured to be 7.8 and 8.7 at.% Ce, respectively. The solubility of Gd in CeMg12(I), in Ce5Mg41 and in (δCe) were measured to be 1.0, 4.6 and 2.4 at.% Gd, respectively. Two continuous series of solid solutions form between GdMg3 and CeMg3, and between GdMg and CeMg. The overall isothermal section at 500 °C was constructed based on the present data with a few extrapolations.

Fabrication of high-strength Mg-Gd-Zn-Zr alloy via selective laser melting

A Mg-11.00Gd-1.77Zn-0.43Zr (wt.%) alloy named GZ112K was prepared by selective laser melting (SLM) with different processing parameters. The formability, element vaporization, microstructure and tensile properties of the SLMed samples at different scanning speed and hatch spacing were characterized. The process map at a constant laser power of 80 W for the alloy has been established. It shows that the optimum scanning speed and hatch spacing are 300–700 mm/s and 100 μm respectively. The SLMed samples have fine grains of about 2 μm and dispersed eutectic phase of β-(Mg,Zn)3Gd due to the very high cooling rate, high solid solubility of Gd and Zn elements in ɑ-Mg matrix owing to the effect of solute trapping. The SLMed GZ112K alloy with scanning speed of 300 mm/s and hatch spacing of 100 μm has yield strength (YS) of 325 MPa, ultimate tensile strength (UTS) of 332 MPa and elongation of 4.0% at room temperature. Compared with as-cast alloy, the SLMed GZ112K alloy has much higher YS (+162 MPa), UTS (+122 MPa) and comparable elongation (+0.4%).

Effects of Zn Content on Hot Tearing Susceptibility of Mg–7Gd–5Y–0.5Zr Alloy

Mg–7Gd–5Y–0.5Zr alloy has excellent mechanical properties but poor hot tearing resistance. The latter makes it difficult to cast billets, which limits the size of subsequently processed parts. Therefore, the hot tearing susceptibility of Mg–7Gd–5Y–xZn–0.5Zr (x = 0, 3, 5, 7 wt%) alloys was studied. It was found that Zn can significantly reduce hot tearing susceptibility of Mg–7Gd–5Y–0.5Zr alloy, which almost linearly decreased with Zn content. When Zn content was 3 wt%, 5 wt% and 7 wt%, hot tearing susceptibility will be reduced by 27%, 83% and 100%, respectively. It was further revealed that the solid solubility of Gd and Y in α-Mg decreased with the increase of Zn content, and the nucleation temperature decreased accordingly, which resulted in the increase of nucleation rate and the refinement of final grains. On the macro level, it showed that the dendrite coherency temperature decreased, the solidification shrinkage stress of α-Mg slowed down, and the residual liquid channel became shorter and hot tearing susceptibility decreased. It was also found that with the increase of Zn content, the content of Zn, Gd and Y enriched on the grain boundary increased, the content of residual liquid phase between dendrites increased after α-Mg crystallization, and the solidified precipitated second phase also changed from Mg5RE phase to long-period stacking ordered phase + W-phase (a little), long-period stacking ordered phase + W-phase (much) and finally to W-phase only. The feeding effect of sufficient intergranular residual liquid on the shrinkage of α-Mg dendrite and the bridging effect of the precipitated phase at the grain boundary (especially long-period stacking ordered phase which is coherent with the parent phase) also led to the decrease of hot tearing susceptibility.

Effect of Mn Modification on Microstructure and Mechanical Properties of Magnesium Alloy with Low Gd Content

The evolution of microstructure and mechanical properties of the dilute Mg–Gd alloy with Mn modification were investigated systematically in this paper. The results show that the combination of Mn and different processing states could adjust the solid solubility of Gd in the Mg matrix, thereby changing the morphology of the second phases and improving the properties of the alloy. With the addition of 0.8 wt% Mn into the Mg–4Gd alloy, the atomic utilization ratio of Gd atoms decreases from 61.5 to 51.8% during the water-cooling casting process, but it increases from 73.8 to 81.0% during homogenization treatment and increases from 72.3 to 84.1% during hot extrusion. Thus, the mean diameter of granular phases of the Mg–4Gd alloy is larger than that of Mg–4Gd–0.8Mn alloy after the isothermal heat treatment. The Mn addition has little effect on the Hall–Petch constant KY and KH of Mg–4Gd alloy, but improves the σ0 value significantly due to the increase of the atomic utilization ratio of Gd atoms. Mn element can improve the mechanical properties of Mg–4Gd alloy, and the increase of yield strength and ductility of as-extruded Mg–4Gd–0.8Mn alloy is mainly attributed to grain refinement and the decrease of the texture intensity. The solid solubility of Gd in Mg matrix can be regulated by the combination of Mn and different processing states, thereby changing the morphology of the second phases and improving the properties of the alloy.

Evolution of LPSO phases in a Mg-Zn-Y-Gd-Zr alloy during semi-continuous casting, homogenization and hot extrusion

A large size Mg-1.2Zn-3.4Y-4.7Gd-0.5Zr (wt%) alloy sheet was manufactured by semi-continuous casting, homogenization and hot extrusion, in which the microstructures were systematically examined. The results showed that: (i) During homogenization, the generation of 14H LPSO phase was mainly achieved by two phase transition processes of “Mg5(Gd,Y,Zn) phase → 14H LPSO phase” and “18R LPSO phase → 14H LPSO phase”. (ii) During extrusion, the evolution of LPSO phases with various morphologies was driven by severe deformation and dynamic recrystallization (DRX). Under severe deformation, the 14H LPSO phases in homogenized alloy were broken down to fragments with various sizes. Under the influence of DRX, the deformation defects of small LPSO fragments were fully eliminated and formed the “sandwich-like” LPSO phase. While the deformation defects of coarse LPSO fragments were less eliminated and formed the “irregular-shaped” LPSO phase. Meanwhile, due to the decreased solubility of Zn, Y and Gd in the extruded alloy matrix, the solution elements of Zn, Y and Gd were impelled to precipitate at the scattering arranged stacking faults (SFs) and formed the “needle-like” LPSO phase. It is found that the gliding of Shockley partial dislocation(s) on basal plane was structurally needed during the precipitation of needle-like LPSO phase.

Experimental Investigation of the Isothermal Section in Fe-Gd-Pd Ternary System at 873 K

Isothermal section of Fe-Gd-Pd ternary system at 873 K has been established by means of x-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscope (SEM) with energy disperse x-ray spectroscopy (EDS) in backscattered electron imaging modes. The isothermal section consists of 14 single-phase regions, 25 two-phase regions, and 12 three-phase regions. At 873 K, no ternary compound was found and the binary inermetallic compounds Gd3Pd and Fe23Gd6 are not stable, whereas the compound Fe23Gd6 decomposes into compounds Fe17Gd2 and Fe3Gd. The XRD and the SEM/EDS analysis show that there is almost no solubility of Gd in the FePd and FePd3 phases, and the solubilities of Pd in Fe17Gd2, Fe3Gd and Fe2Gd and Fe in GdPd2, α-Gd3Pd4 and Gd3Pd2 are all less than 1 at.%. Meanwhile, the solubilities of Fe in GdPd3, α-GdPd and Gd7Pd3 are determined to be as high as 1.37, 5.31, and 4.18 at.% Fe, respectively.

Achieving High Strength and Good Ductility in As-Extruded Mg-Gd-Y-Zn Alloys by Ce Micro-Alloying.

In this study, the effect of Ce additions on microstructure evolution of Mg–7Gd–3.5Y–0.3Zn (wt %) alloys during the casting, homogenization, aging and extrusion processing are investigated, and novel mechanical properties are also obtained. The results show that Ce addition promotes the formation of long period stacking ordered (LPSO) phases in the as-cast Mg–Gd–Y–Zn–Ce alloys. A high content of Ce addition would reduce the maximum solubility of Gd and Y in the Mg matrix, which leads to the higher density of Mg12Ce phases in the as-homogenized alloys. The major second phases observed in the as-extruded alloys are micron-sized bulk LPSO phases, nano-sized stripe LPSO phases, and broken Mg12Ce and Mg5RE phases. Recrystallized grain size of the as-extruded 0.2Ce, 0.5Ce and 1.0Ce alloys can be refined to ~4.3 μm, ~1.0 μm and ~8.4 μm, respectively, which is caused by the synthesized effect of both micron phases and nano phases. The strength and ductility of as-extruded samples firstly increase and then decrease with increasing Ce content. As-extruded 0.5Ce alloy exhibits optimal mechanical properties, with ultimate strength of 365 MPa and ductility of ~15% simultaneously.

Stabilization of LnB12 (Ln = Gd, Sm, Nd, and Pr) in Zr1-xLnxB12 under Ambient Pressure.

We report ambient pressure stabilization of a previously synthesized high-pressure (6.5 GPa) phase, GdB12, in a Zr1-xGdxB12 solid solution (with ∼54 at. % Gd solubility, as determined by both powder X-ray diffraction and energy-dispersive spectroscopy). Limited solubilities of Sm (∼15 at. % Sm), Nd (∼7 at. % Nd), and Pr (∼4 at. % Pr), in ZrB12 were also achieved. Previous attempts at preparing these rare-earth borides were unsuccessful even under high pressure. On the basis of insights provided from the unit cell sizes observed via solid solutions, at least 6.5 GPa of pressure would be needed to synthesize these rare-earth borides since Sm, Nd, and Pr atomic radii are larger than that of Gd. The solid-solution formation for Zr1-xGdxB12 and Zr1-xSmxB12 can be seen in the change of the unit cell of each of the solid solutions relative to their pure parent compounds as well as in the change of color of the respective alloys. For Zr0.45Gd0.55B12 and Zr0.70Sm0.30B12, the cubic unit cell parameter (a) reached a value of 7.453 and 7.428 Å, respectively, compared to 7.412 Å for pure ZrB12.

Effects of Gd addition on the thermal and microstructural behaviors of the as-cast Cu–9 %Al and Cu–9 %Al–10 %Mn alloys

The effects of Gd addition on the thermal and microstructural behaviors of as-cast samples of the Cu–9 %Al and Cu–9 %Al–10 %Mn alloys were investigated using different experimental techniques. The results showed that the addition of Gd does not significantly interfere in the melting and solidification temperatures of the Cu–9 %Al alloy, but it decreases the stability of β′ martensitic phase during re-heating of sample, while the presence of Mn slows the β(A2) phase decomposition during cooling and widens its stability field. The Cu–9 %Al–10 %Mn–3 %Gd alloy has characteristics close to those observed for the Cu–9 %Al–10 %Mn alloy, but the presence of Mn increases the solubility of Gd and induces the formation of Gd-rich precipitates with average size of 200 nm.

Isothermal section of Mg–Nd–Gd ternary system at 723 K

An isothermal section of the Mg–Nd–Gd ternary system at 723 K was established by diffusion triple technique and electron probe microanalysis (EPMA). Mg3Gd and Mg3Nd form a continuous solid solution (Gd, Nd)3Mg, and a continuous solid solution (Gd, Nd)Mg is also formed between MgGd and MgNd. Mg7Gd, Mg5Gd, Mg2Gd, Mg41Nd5, (Gd, Nd)3Mg and (Gd, Nd)Mg are found in the ternary system. In these intermetallic phases, Mg7Gd has been reported to be a metastable phase in previous literatures. The solubilities of Mg, Gd and Nd in all the phases were detected. Furthermore, four three-phase equilibria, α(Mg)+Mg7Gd+ Mg41Nd5, Mg7Gd+Mg5Gd+Mg41Nd5, Mg5Gd+Mg41Nd5+(Gd, Nd)3Mg and (Gd, Nd)3Mg+(Gd, Nd)Mg+Mg2Gd, were identified in the isothermal section.