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The fabrication of a single-phase (Ni,Pt)Al coating, doped with zirconium, was achieved via a method that included the simultaneous electroplating of a Pt-Zr layer, followed by a process of gas-phase aluminizing. The Zr-doped (Ni,Pt)Al coating was then subjected to an evaluation of its isothermal oxidation resistance at a temperature of 1150 °C in static air compared with a conventional (Ni,Pt)Al coating. The findings indicated that the incorporation of zirconium into the (Ni,Pt)Al coating led to a marked escalation in the rate of oxidation and a worse-scale spallation resistance, which was totally opposite to the results obtained at 1100 °C. The harmful effect of Zr on the oxidation resistance of the coating is discussed in this paper. [ABSTRACT FROM AUTHOR]

In this study, the microstructural properties and corrosion behavior of RE elements (Y, La) added to magnesium in varying minors after casting and homogenization heat treatment were investigated. Three-phase structures, such as α-Mg, lamellae-like phases, and network-shaped eutectic compounds, were seen in the microstructure results. The dendrite-like phases were evenly distributed from the eutectic compounds to the interior of the α-Mg grains, while the eutectic compounds (α-Mg + Mg) RE (La/Y)) were distributed at the grain boundaries. According to the corrosion results, the typical hydroxide formation for lanthanum content caused the formation of crater structures in the material, and with the increase in lanthanum content, these crater structures increased both in depth and in density. In addition, the corrosion products formed by Y2O3 and Y(OH)3 in the Mg-3.21Y-3.15 La alloy increased the thickness of the corrosion film and formed a barrier that protects the material against corrosion. The thinness of the protective barrier against corrosion in the Mg-4.71 Y-3.98 La alloy is due to the increased lanthanum and yttrium ratios. In addition, the corrosion resistance of both Mg-3.21Y-3.15 La and Mg-4.71 Y-3.98 La alloys decreases after homogenization. This negative effect on corrosion is due to the coaxial distribution of oxide/hydroxide layers formed by yttrium and lanthanum after homogenization. [ABSTRACT FROM AUTHOR]

The effects of minor RE (Y, La) on microstructure and corrosion behavior of TX31 alloys are systemically investigated. The results show that the CaMgSn phase of TX31-RE alloys is an outstanding thermally stable phase. The addition of little Y, La of the alloys after homogenization does not form new phases. Meanwhile, the minor Y, La can refine the dendritic structure in the TX31 alloys. The Y, La elements can reduce the corrosion rate and increase the corrosion film resistance of the TX31 alloys. The corrosion resistance of La-containing TX31 alloy is better than that of Y-containing TX31. The corrosion of the alloys is typical pitting corrosion because of the potential difference between CaMgSn phases and Mg matrix. The corrosion products are mainly Mg(OH)2, Ca(OH)2, MgO, and SnO2. The RE (Y, La) forms the RE oxide/hydroxide and also promotes the formation of a small amount of CaO. The RE oxide/hydroxide and CaO fill the holes in the metal hydroxides (Mg(OH)2 and Ca(OH)2) films and weaken the penetration rate of Cl−, which improves the corrosion resistance of the RE-containing TX31 alloys.

In this study, the microstructural properties and corrosion behavior of RE elements (Y, La) added to magnesium in varying minors after casting and homogenization heat treatment were investigated. Three-phase structures, such as α-Mg, lamellae-like phases, and network-shaped eutectic compounds, were seen in the microstructure results. The dendrite-like phases were evenly distributed from the eutectic compounds to the interior of the α-Mg grains, while the eutectic compounds (α-Mg + Mg) RE (La/Y)) were distributed at the grain boundaries. According to the corrosion results, the typical hydroxide formation for lanthanum content caused the formation of crater structures in the material, and with the increase in lanthanum content, these crater structures increased both in depth and in density. In addition, the corrosion products formed by Y2O3 and Y(OH)3 in the Mg-3.21Y-3.15 La alloy increased the thickness of the corrosion film and formed a barrier that protects the material against corrosion. The thinness of the protective barrier against corrosion in the Mg-4.71 Y-3.98 La alloy is due to the increased lanthanum and yttrium ratios. In addition, the corrosion resistance of both Mg-3.21Y-3.15 La and Mg-4.71 Y-3.98 La alloys decreases after homogenization. This negative effect on corrosion is due to the coaxial distribution of oxide/hydroxide layers formed by yttrium and lanthanum after homogenization.

The poor wear resistance of magnesium (Mg) alloys has hindered their widespread application. Therefore, researchers have focused on how the addition of rare earth (RE) elements to Mg alloys and the modification methods affect their tribological behaviour. This overview reflects the research on the wear of Mg alloys. Several treatments and modification methods have been utilised to improve the wear behaviour of Mg alloys, including cryogenic treatment, deep cryogenic treatment, precipitation hardening, surface mechanical attrition treatment (SMAT) and laser surface melting. Accordingly, except for SMAT, the other processes positively affected the wear resistance. Therefore, adding RE elements to Mg alloys and applying modification processes improve the wear resistance, especially at high temperatures. [ABSTRACT FROM AUTHOR]

A fine-grained 55Mg-35Pb-9.2Al-0.8B alloy was fabricated through equal channel angular pressing (ECAP) with the addition of rare earth (RE). The corrosion behavior of the alloy was investigated by electrochemical test, hydrogen evolution test and salt spray test. The results demonstrate the corrosion resistance ranking of the as-cast specimens with RE elements as follows: 0.5Sc > 0.5Y > 0.5Sm > 0.5Ce > 0.5Nd > as-cast. After the 1st ECAP process, the corrosion resistance of the alloy samples follows this order: 0.5Sc > 0.5Ce > 0.5Y > 0.5Sm > 0.5Nd > as-cast. The addition of 0.5Sc has the most significant effect on the improvement of corrosion resistance of the alloy. At the same time, the corrosion resistance of 0.5Ce alloy was improved after ECAP. The microstructure of 55Mg-35Pb-9.2Al-0.8B alloy was refined and the dispersion of the second phase was reduced by adding RE elements and ECAP. Grain refinement can stabilize the corrosion product layer and improve corrosion resistance. This study lays the foundation for comprehending and future applications of the ECAP process in fabricating high-performance Mg-Pb-Al-B-RE alloys. • According to electrochemical test analysis, the alloy with 0.5Sc has the most remarkable corrosion resistance. • From the perspective of electronegativity and thermodynamics, Al 3 Sc and Al 4 Ce are preferentially formed in the alloy. • The application of rare earth elements and ECAP affects the microstructure of the alloy and refines the grains. [ABSTRACT FROM AUTHOR]

Based on crystal slip theory, the rafting of γ′ precipitate phases, the atomic diffusion of Re, the growth mechanism of topologically close-packed (TCP) phases and the microcrack initiation and propagation near TCP phases during creep deformation in a single crystal superalloy were studied at 1100 °C and 140 MPa. The results show that the γ′ rafting process is accompanied by moving dislocations. The diffusion along with dislocations is the main reason for the enrichment of Re in the TCP phases. In the state of uniaxial tensile stress along the [001] direction, the octahedral and dodecahedral slip systems may open, and the hexahedral slip system may close. TCP phases grow along the slip systems (111)[-1-12], (-1-11)[112], (-11-1)[1-1-2] and (1-1-1)[-11-2]; the Schmidt factors of which are larger than the others. Meanwhile, the four slip systems have the maximum resolved shear stress. Microcracks usually generate near TCP phases and propagate along the TCP phase growth direction and the slip system families. The angle is approximately 70.5° between the TCP phase growth direction and the slip plane. In other words, cracks generate and propagate along the slip systems (-1-11)[112] and (111)[-1-12]. The microcrack propagation direction corresponds to the theoretical calculation result and the zigzag propagation of a macrocrack in the tenon of an aero-engine single crystal turbine blade. [ABSTRACT FROM AUTHOR]

Mg–3Li–0.4Zr alloys containing RE elements (Gd, La, Nd) (Mg–3Li–RE–0.4Zr alloys) are investigated to reveal the influence of homogenization treatment on microstructures and distributions of RE, Zr elements. It is found that 300 °C × 24 h homogenization treatment shows better improvement on the microstructure including the refinement of grain size, the dispersion of cellular dendrite and low melting point particles. Before treatment, La and Nd segregate effectively at grain boundary and Zr segregates in the form of precipitates. Homogenization treatment induces the reduction of RE segregation. However, the segregation of Zr in precipitates cannot be abated due to the relatively low diffusion rate compared with RE elements. [ABSTRACT FROM AUTHOR]

Abstract: Effects of different rare-earth (RE) elements (i.e., Y, Ce, La and Yb) on the glass forming-ability (GFA) of Al–Ca–Ni alloy system were systematically investigated. The optimum addition content of all the four RE is 1at.% and ytterbium is the most effective as far as the GFA is considered. Our analysis confirmed that proper additions of Yb could not only impede the formation of the competing α-Al clusters, but also enhance the liquid stability (i.e., lower the liquidus temperature). Although additions of Y, Ce and La in the Al88Ca7Ni5 can also retard the α-Al precipitation, nevertheless, it seemed that their large atomic size difference with Ca could destabilize the original liquid stability (i.e., increase the liquidus temperature). [Copyright &y& Elsevier]

Abstract: In the present paper the influence of RE alloying additions (Y, Gd, Tb and Dy) on magnetic properties (Curie temperatures, low temperature magnetization, zero field cooling–field cooling curves, domain structure, room temperature magnetostriction and magnetic permeability) of amorphous alloys of type Fe82Nb2B14RE2 are carefully examined. It was shown that substituting of yttrium atoms by magnetic elements, i.e. Gd, Tb and Dy leads to (i) an increase of the Curie temperature of amorphous phase from 416K (for Fe82Nb2B14Y2) to 450K (for Fe82Nb2B14Gd2) and (ii) a decrease of magnetization in saturation (magnetic field 7T) which can be explained by antiferromagnetic Fe–RE coupling resulting in a decrease of magnetic moment calculated per magnetic atom from 2.00μB for the Fe82Nb2B14Y2 alloy (Fe in amorphous phase) to 1.51μB for the Fe82Nb2B14Tb2 alloy. It was concluded that Tb and Dy alloying additions introduce a local magnetic anisotropy responsible for significant decrease of initial magnetic permeability (about 5 times in relation to Fe82Nb2B14Y2 or Fe82Nb2B14Gd2 alloy), increase of magnetic irreversibility effect measured at 2K (about 10 times in relation to the same alloys) and appearing of the finger-print magnetic domain regions (not observed for the Fe82Nb2B14Y2 and Fe82Nb2B14Gd2 alloys). [Copyright &y& Elsevier]

Abstract: High temperature mechanical properties of equal channel angularly pressed (ECAPed) AZ31 magnesium alloy with 0.6%RE, 0.6%Ca and 0.3%RE–0.3%Ca additions were investigated. After extruding, the materials were ECAPed for 4 passes using route BC. Due to the textural effects induced by ECAP, the flow stress of the ECAPed AZ31 was lower than that of the extruded alloy at 523K while tensile ductility was not changed. Thermal stability of the grain structure was achieved by RE-and Ca-containing particles, mainly due to the suppression of grain growth. Addition of the RE elements and calcium increased tensile strength mainly by dispersive strengthening effects of particles. The improved tensile ductility of the extruded material, however, was achieved by the presence of stable fine grains. Among all tested materials, AZ31-0.6%RE showed the maximum ductility of 198% at 523K and a strain rate of 10−4 s−1. [Copyright &y& Elsevier]

Abstract: The effects of 0.6wt.%RE, 0.6wt.%Ca and 0.3wt.%RE+0.3wt.%Ca additions on the microstructure and mechanical properties of equal channel angularly pressed (ECAPed) AZ31 magnesium alloy were investigated. After extruding, the materials were ECAPed for 1, 2, and 4 passes using route BC. After 4 passes of ECAP, AZ31 showed lower yield stress and higher ductility respect to the as-extruded condition, indicating that texture softening has overcome the strengthening effects of grain refinement. The introduction of RE elements and calcium in the AZ31 resulted in further refinement of the grain structure, mainly due to the suppression of the dynamic recrystallization by RE- and Ca-containing particles during the hot deformation process. Addition of the RE elements and calcium increased tensile strength mainly by dispersive strengthening effects of particles, and improved tensile ductility of the extruded material by texture modification. [Copyright &y& Elsevier]

This study was concerned with the effect of thermal aging on the impact properties of solder joints. Three kinds of solders, conventional Sn-37Pb solder, Sn-3.8Ag-0.7Cu solder, and Sn-3.8Ag-0.7Cu doped with rare-earth (RE) elements, were selected to manufacture joint specimens for the Charpy impact test. U-notch specimens were adopted and isothermally aged at 150°C for 100 h and 1000 h, and then impacted by using a pendulum-type impact tester at room temperature. The Sn-37Pb solder joints exhibited higher performance in terms of impact absorbed energy in the as-soldered and 100 h thermally aged conditions. Interestingly, the Sn-3.8Ag-0.7Cu solder joints exhibited improved performance for the impact value after 1000 h of thermal aging. For the Sn-37Pb and Sn-3.8Ag-0.7Cu solder joints, the impact absorbed energies initially increased when the storage duration was limited to 100 h, and then gradually decreased with its further increase. For the Sn-3.8Ag-0.7Cu-RE specimens, impact performance decreased directly with increasing thermal aging. Furthermore, scanning electron microscopy (SEM) observation showed that the fracture paths were focused on the interface zone for the three kinds of joints in the aged conditions. For the Sn-37Pb joints, the fracture surfaces mainly presented a ductile fracture mode. For the Sn-3.8Ag-0.7Cu joints, with microstructure coarsening, crack propagation partly shifted towards the Sn/Cu6Sn5 interface. Compared with the 100 h aged joints, the area fraction of intergranular fracture of Sn grains on the Sn-3.8Ag-0.7Cu fracture surfaces was increased when the aging time was 1000 h. On the contrary, the fracture morphologies of Sn-3.8Ag-0.7Cu-RE were mainly brittle as thermal aging increased. Thus, an interrelationship between impact energy value and fracture morphology was observed. [ABSTRACT FROM AUTHOR]

Charpy impact tests on three kinds of as-soldered U-notch specimens were performed with reference to the American Society of Testing Materials (ASTM) standard E23-07 by using a pendulum-type impact tester at room temperature. Three kinds of solders, conventional Sn-37Pb, Sn-3.8Ag-0.7Cu, and Sn-3.8Ag-0.7Cu doped with rare-earth (RE) elements, were selected to fabricate the joint specimens for the impact test. The three joints demonstrate similar impact toughness values, with averages of 11.4 kJ/m², 10.4 kJ/m², and 11.0 kJ/m², respectively. Under observation by scanning electron microscopy (SEM), the Sn-37Pb joint exhibited mainly ductile fracture morphology. Fractographic observations of lead-free joints exhibited a mixture of ductile and brittle morphologies. The addition of RE elements resulted in an impact toughness that was slightly higher than that of the Sn-3.8Ag-0.7Cu alloy. The impact toughness and the fracture mode were notably dependent on the type of solder. Additionally, the thickness of the intermetallic compound (IMC) layer had a remarkable influence on the fracture path and impact toughness of the solder joints. [ABSTRACT FROM AUTHOR]

Abstract: Polycrystalline strontium–europium hydroxovanadates Sr10− x Eu x (VO4)6(OH)2− x O x were synthesized and studied by X-ray powder diffraction, infrared absorption and diffuse-reflectance spectroscopies and also thermogravimetry. The single-phase region of isomorphous substitution of Eu for Sr in hydroxovanadate has been found to lie in the compositional interval 0⩽x⩽0.18 at 800°C. Refinement of X-ray diffraction (XRD) patterns by the Rietveld method shows that Eu substitutes for Sr preferentially at the Sr(1) sites of the apatite structure. The substitution results in a more uniform distribution of Sr–O bond lengths in coordination polyhedra both around Sr (1) and Sr (2) sites and also in a slight contraction of the vanadate anion VO4 3−. Synthetic Sr hydroxovanadates absorb a considerable amount of water in two forms: capillary condensed and chemically combined. The latter form may be absorbed at temperatures as high as 500°C. [Copyright &y& Elsevier]

Novel Zn 0·95 La 0·05 O and co-doped Zn 0·9 La 0.05 M 0.05 O (M = Yb, Nd, Sm) nanocrystals were prepared by co-precipitation method. Different analytical techniques such as XRD, FTIR, SEM, and UV–vis were used to investigate the effect of doping of rare-earth (RE) ions in ZnO lattice. The microstructural study was performed using Scherrer, W–H, and SSP methods. UV–vis analysis has shown that the energy bandgap is redshifted (3.2–2.8 eV) by rare-earth (RE) ions doping in ZnO. The other optical parameters were also investigated to strengthen the optical study. The photocatalytic performance of grown catalysts was tested under direct sunlight against methylene blue (MB), rhodamine-B (RhB), and phenol (Ph). The antibacterial activity was carried out against S. aureus and P. Vulgaris bacteria. The La/Sm co-doped nanocrystal has the highest photocatalytic and antibacterial activity than others grown catalysts. • Enhanced optical properties of rare earth (RE) ions (La3+, Yb3+, Nd3+, and Sm3+) co-doped ZnO nanocrystals. • XRD, FTIR, UV–vis and SEM techniques were used. • Microstructural parameters of RE ions co-doped ZnO nanoparticles studied in detail. • Photocatalytic and antibacterial application of grown nanocrystals was performed. [ABSTRACT FROM AUTHOR]