Yttrium Addition Research Articles

Effect of Alloy Microstructure on the Corrosion Behavior of Binary Mg-Y Alloys

In recent years, magnesium alloys continue to receive attention due to their low density and high specific strength compared to other metallic materials. However, the main disadvantage of magnesium alloys originates from the low standard reduction potential of magnesium (-2.37 VSHE), resulting in high reactivity in water-containing environments and susceptibility to corrosion reaction. This kind of corrosion phenomenon exists in most magnesium alloys, thus limiting their practical applications.At present, many studies showed that adding yttrium to magnesium can simultaneously improve its creep and corrosion resistance. Also, the standard reduction potential of yttrium is similar to that of magnesium, which implies that the galvanic corrosion effect due to the second phases or precipitates would be less pronounced with the addition of yttrium. Therefore, in this study, we investigated the influence of alloy microstructure on the corrosion behavior of two binary magnesium-yttrium (Mg-Y) alloys with different yttrium content.To understand the dominant features during corrosion tests, this study used an in situ optical microscope (OM)/three-electrode setup to monitor the evolution in corrosion potential and surface corrosion morphology with immersion times of the Mg-Y alloys. With this setup, serious localized corrosion was observed on the Mg-1wt%Y sample. In contrast, localized corrosion on the Mg-7wt%Y sample is mitigated, and the corrosion rate is maintained at a similar level over time. Even though the addition of more Y results in more second phases or precipitates, which could cause some galvanic effect, the corrosion propagation is delayed by the second phase distribution. Through further observation in scanning electron microscope (SEM) and focused ion beam (FIB) systems, the corrosion mechanism of binary Mg-Y alloys will be discussed based on the distribution of local cathodes and anodes on the alloy surface. Figure 1

Improving Tension/Compression Asymmetry of a Hot‐Extruded Mg–Zn–Y–Zr Alloy via Yttrium Addition

In this study, effects of different yttrium (Y) contents ranging from 0 to 2.5 wt% on the microstructure and tension/compression asymmetry of as‐extruded Mg–5.5Zn–0.6Zr alloys are investigated. The influence of Y on improving the tension/compression yield strength is been studied. The results show that the volume fractions of the microscale I (Mg3YZn6) and W (Mg3Zn3Y2) phases remarkably increase with Y addition. Simultaneously, the nanoscale MgZn and Mg–Zn–Y phases uniformly precipitate during extrusion. Benefiting from the pinning of second phases, the microstructure is strikingly refined from 16.3 to 5.5 μm. Among them, the Y element promotes grain refinement most effectively when the Y content is 2.0 wt%. Second phase strengthening and fine‐grain strengthening enhance the hardening rate and suppress twinning, which leads to the improvement of the tension/compression asymmetry. Specifically, yield strength of 231 MPa and ultimate tensile strength of 312 MPa are achieved with 2.5 wt% Y addition. The relative increment is about 33.0% and 65.3% compared to the unmodified alloy, respectively. In addition, the tensile yield strength to compressive yield strength ratio (TYS/CYS) is reduced from 1.30 to 1.09.

Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9Zn Lead-Free Solders Alloy.

Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.

Comparative study for microstructural characterisations and properties of Ti-Y powders produced by vacuum induction gas atomization cold crucible process

ABSTRACT Ti-based alloy powder is an excellent candidate as an additive manufacturing material, owing to its high strength-to-weight ratio, corrosion resistance and biocompatibility. However, molten Ti is highly reactive with ceramic crucibles. Thus, only crucible-free techniques can be used, limiting the manufacturing. In this study, Ti–Y, CP-Titanium powder was manufactured using the vacuum induction gas atomization cold crucible (VIGA-CC) process, without using any master alloy; moreover, its properties were elucidated. Characterisations were performed to comparatively analyse the surface morphology, impurity content and mechanical properties of the synthesised powder. It was found that the powder had a uniform composition and was refined by the yttrium addition. The VIGA-CC process, by which alloy powders with various compositions can be prepared, is expected to expand the list of target alloys that can be used in additive manufacturing processes.

Size-driven phase transformation and microstructure evolution of ZrO2 nanocrystallites associated with thermal treatments

Thermal stability of nanocrystallites plays an important role in the manufacturing and application of nanocrystalline ceramics/glass-ceramics. This study explores the effects of thermal treatments on the microstructures of two ZrO2-SiO2 nanocrystalline glass-ceramics (NCGCs), an undoped one and a yttria-doped one. The two as-sintered NCGCs were composed of tetragonal (t) and monoclinic (m) ZrO2 nanocrystallites, and SiO2 component was amorphous. t-ZrO2 and m-ZrO2 nanocrystallites were metastable during thermal treatment. The content of m-ZrO2 in the undoped ZrO2-SiO2 NCGC first increased after thermal treating at 850 °C for 5 h, then decreased after thermal treating at and above 950 °C. After thermal treating at 1250 °C for 5 h, t-ZrO2 nanocrystallites experienced a rapid phase transformation during cooling, resulting the formation of 88.6 vol% m-ZrO2. Size-driven phase transformation was utilized to explain the metastability of t-ZrO2 and m-ZrO2 nanocrystallites. In contrast, the content of m-ZrO2 in the yttria-doped ZrO2-SiO2 NCGC continuously decreased with the increase of thermal treatment temperature. The addition of yttria improved the phase stability of t-ZrO2 up to at least 1250 °C. Crystallite size of both t-ZrO2 and m-ZrO2 nanocrystallites increased with the increase of thermal treatment temperature in the two NCGCs. The presence of residual thermal stress in the as-sintered NCGCs changed the lattice spacing of t-ZrO2 and m-ZrO2 nanocrystallites, and the stress can be released after thermal treatment. Thermal treatment exerts significant influences on the microstructure of ZrO2-SiO2 NCGCs.

Effects of Yttrium Addition on Bending Deformation Behavior of Magnesium Single Crystals

Effects of Yttrium Addition on Bending Deformation Behavior of Magnesium Single Crystals

Effects of yttrium addition on thermoplastic formability of Zr-Cu-Ni-Al amorphous alloy under non-isothermal condition

A low-cost and Be-free Zr-based amorphous system with excellent thermoplastic formability has been developed by doping a small amount of Y element. Based on the thermodynamic test data, Y addition can increase the supercooled liquid region of Zr-based amorphous alloy when it is less than 2 at%, leading to a relatively wider temperature range of thermoplastic forming. The compression experimental results reveal that (Zr0.507Cu0.28Ni0.9Al0.123)98.5Y1.5 (ZrY1.5) alloy possesses the largest Dmax value (the maximum diameter of the compressed cylindrical specimen) than other Zr-based amorphous alloys prepared in this study, thereby confirming its superior thermoplastic formability. A lower viscosity can be observed on the TMA curves of ZrY1.5 alloy, suggesting that appropriate Y addition decreases the viscous resistance of amorphous supercooled liquid. However, the more obvious deviation from Vogel–Fulcher–Tamann theoretical model indicates the weak Arrhenius temperature dependence of viscous flow behavior. The parameter ΔTTPF/D*, where ΔTTPF represents the temperature range of thermoplastic forming and D* denotes the fragility index, is found to be an effective indicator for evaluating the thermoplastic formability of the investigated Y addition Zr-based amorphous system. Finally, Zr-based amorphous nanopillar arrays have been successfully fabricated under non-isothermal condition, which further proves that Y addition Zr-based amorphous alloy is a promising candidate for nanomolding material.

Glass-Forming Ability and Corrosion Resistance of Al88Y8-xFe4+x (x = 0, 1, 2 at.%) Alloys.

The effect of iron and yttrium additions on glass forming ability and corrosion resistance of Al88Y8-xFe4+x (x = 0, 1, 2 at.%) alloys in the form of ingots and melt-spun ribbons was investigated. The crystalline multiphase structure of ingots and amorphous-crystalline structure of ribbons were examined by a number of analytical techniques including X-ray diffraction, Mössbauer spectroscopy, and transmission electron microscopy. It was confirmed that the higher Fe additions contributed to formation of amorphous structures. The impact of chemical composition and structure of alloys on their corrosion resistance was characterized by electrochemical tests in 3.5% NaCl solution at 25 °C. The identification of the mechanism of chemical reactions taking place during polarization test along with the morphology and internal structure of the surface oxide films generated was performed. It was revealed that the best corrosion resistance was achieved for the Al88Y7Fe5 alloy in the form of ribbon, which exhibited the lowest corrosion current density (jcorr = 0.09 μA/cm2) and the highest polarization resistance (Rp = 96.7 kΩ∙cm2).

EVALUATION OF THE PHOTOCATALYTIC ACTIVITY OF α-MoO3 DOPED WITH RARE EARTH ELEMENTS ( La , Y ) FOR THE REMOVAL OF METHYL RED DYE

This study deals with the use of molybdenum trioxide doped with different quantities of lanthanum or yttrium as catalysts in the photocatalytic processes for removing methyl red from aqueous solution. Crystalline structure, surface area, pore volume, and pore diameter, characteristics that may significantly affect the photocatalytic activity of materials, have been studied, during the addition of lanthanum or yttrium to MoO3, using several advanced techniques such as X-ray diffraction, Raman spectrometry, and nitrogen absorption. Diffraction patterns did not show any changes in MoO3 structure when the doping rate was smaller than 0.6. In doping rates, greater than 0.6, new diffraction peaks related to other compounds have been noticed only in the case of LxMoO3. The addition of lanthanum or yttrium has increased the surface area of prepared materials, which contribute to enhancing the photcatalytic activity where the degradation rate of methyl red has reached to about 60% in the case of LxMoO3 and to 95% in the case of YxMoO3.

Influence of yttrium on purification and carbide precipitation of superalloy K4169

The effect of reactive element yttrium on purification and carbide precipitation of superalloy K4169 has been studied through vacuum induction melting. The results show that yttrium has a strong deoxidizing and desulfurizing ability, and the impurity elements of sulfur and oxygen in melting K4169 are greatly reduced to 2−5 ppm and 4−5 ppm, respectively. The metallurgical reaction product is mainly Y2O3 and yttrium containing sulfides have not been observed. With the increase of the content of yttrium from 0.005 wt.% to 0.033 wt.%, the morphology and size of MC carbides in casting are significantly influenced due to that the yttrium changes the diffusion of the carbide forming elements and solid fraction during solidification. In the alloys without yttrium, only isolated blocky or strip carbides exist, while skeleton-like carbides are observed in the alloys with yttrium. Both the average size and the number density of skeleton carbides decrease monotonously with yttrium content increasing. After yttrium increasing to 0.033 wt.%, a phase of hexagonal Ni17Y2 is observed to precipitate in the form of symbiosis with MC carbide and matrix. The addition of yttrium is not beneficial for the properties of K4169 alloys at the room temperature, which is quite related to the MC carbides with a large skeleton-like morphology through the analysis of tensile fracture.

Effect of yttrium ion on electrical and magnetic properties of barium based spinel ferrites

Sol–gel technique is utilized to produce the series of ferrite having chemical formula BaYyFe2-yO4 (y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10). The cubic structure of all the samples have been revealed through X-ray diffraction data. The inclusion of yttrium content among the ferrites beyond 0.06, it will result into development of YFeO3 secondary phase. The lattice parameter of samples upsurges with the substitution of yttrium ions (Y3+). Jump lengths on A & B sites, bond lengths and ionic radii have direct relation with yttrium concentration. The evaluation of electrical parameters reveal that the resistivity, activation energy and bond length increased with the growth of yttrium. Below the Curie temperature, the movement of electrons and holes is main cause of conduction mechanism. But above this temperature, the polaron hopping handle the conduction process. With the addition of yttrium, the saturation magnetization value decreased. Coercivity of samples enlarged with the substitution of yttrium ions. The involvement of yttrium ion in barium ferrite system makes it appropriate for high frequency appliances.

Effects of yttrium additions on microstructures and mechanical properties of cast Al-Cu-Mg-Ag alloys

The effects of microalloying with yttrium on the microstructures and mechanical properties of cast Al-Cu-Mg-Ag alloys at ambient and elevated temperatures are investigated using tensile testing, differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The present results reveal that the strength properties of peak-aged Al-Cu-Mg-Ag alloys at 300 °C are considerably improved with the additions of Y. Al8Cu4Y phase is found to segregate at the localized regions along grain boundaries and strengthens the grain boundaries at elevated temperature. However, the Ω precipitation is gradually suppressed by Y additions, thereby degrading the strength of Al-Cu-Mg-Ag alloys at ambient temperature. This negative effect of Y is directly associated with the formation of blocky (Cd, Ag, Ti, V, Y)-rich intermetallics, which consumes the available Ag atoms for Ω nucleation and hence leads to the lower number density of Ω plates.

The effects of Y pre-alloying on the in-situ dispersoids of ODS CoCrFeMnNi high-entropy alloy

Oxide dispersion strengthened CoCrFeMnNi high-entropy alloys (ODS-HEAs) were prepared using two different powder preparation methods classified by yttrium addition strategy to investigate the effects of in-situ and ex-situ oxide dispersoid formation on the microstructure and mechanical properties. Systematic microstructural analysis was carried out by X-ray diffraction (XRD), electron backscattered diffraction (EBSD), high-resolution transmission electron microscopy (HRTEM), atom probe tomography (APT), and small-angle neutron scattering (SANS). Cryo-milled powder analysis, grain structure evolution after spark plasma sintering, dispersoid characteristics, and matrix/dispersoid interface structure analysis of the in-situ and ex-situ dispersoids within the high-entropy alloy (HEA) matrix were performed. The in-situ dispersoid formation was dominantly observed in the Y-alloyed ODS-HEA through the construction of a coherent interface relationship with complex chemical composition, leading to an increase in the Zener pinning forces on the grain boundary movement. ODS-HEA with in-situ oxide dispersoids enhanced the formation of ultrafine-grained structures with an average diameter of 330 nm at a sintering temperature of 1173 K. This study shows that the Y pre-alloying method is efficient in achieving fine coherent dispersoids with an ultrafine-grained structure, resulting in an enhancement of the tensile strength of the CoCrFeMnNi HEA.

Low temperature synthesis of metastable tetragonal yttria doped hafnia T-(Y-HfO2) nanoparticles through mechanochemical processing and annealing

For polymorphic binary metal oxides, such as HfO2, the availability of metastable phases with distinct physical and chemical properties opens a wide field of new applications. Hafnia (HfO2) is used as a thermal barrier coating in high temperature structural materials and as an electronic material (gate oxide) in the metal-oxide semiconductor field-effect transistors (MOSFETs). Its diverse functionality may be further tailored by phase selection and stabilization. The tetragonal polymorph with its high dielectric constant and wide bandgap is important in MOSFET applications. However, the temperature required to stabilize the metastable tetragonal phase is around 1700-1800 °C, making it difficult to synthesize large tetragonal nanoparticles or even bulk materials. In this project, tetragonal HfO2 (T-HfO2) nanoparticles were produced at relative low temperature (1100 °C) by employing mechanochemical processing with the addition of yttrium. Structural characterization using XRD, and HRTEM analysis revealed that the as-milled powders are a mixture of T-HfO2, residual monoclinic HfO2 (M − HfO2) and an amorphous component. Subsequent annealing transforms residual M − HfO2 and any remaining amorphous material into T-HfO2 as well. A viable route for stabilizing thermodynamically unfavored phases in the HfO2 system is described.

Tensile Deformation Behavior of Magnesium Single Crystals with Different Yttrium Concentrations

Tensile tests of Mg-Y single crystals with different yttrium concentrations: 0.07 and 0.3 at.% were carried out to investigate effects of yttrium on pyramidal <c+a> slip system. In Mg-0.07at%Y alloy single crystals, {11 2}< 23> second order pyramidal <c+a> slip was activated and yield stress increased, compared to pure Mg single crystals. On other hand, in Mg-0.3at%Y alloy single crystals, {10 1}< 23> first order pyramidal <c+a> slip was activated and yield stress increased, compared to Mg-0.07at%Y alloy single crystals. The change in slip system by yttrium addition would be caused by increasing critical resolved shear stress (CRSS) for second order pyramidal slip.

Chlorine-Induced High Temperature Corrosion of Inconel 625 Alloy with the Addition of Yttrium at 800 °C

Chlorine-Induced High Temperature Corrosion of Inconel 625 Alloy with the Addition of Yttrium at 800 °C

Role of Yttrium Addition and Annealing Temperature on Thermal Stability and Hardness of Nanocrystalline CoCrFeNi High Entropy Alloy

Role of Yttrium Addition and Annealing Temperature on Thermal Stability and Hardness of Nanocrystalline CoCrFeNi High Entropy Alloy

Role of Yttrium Addition and Annealing Temperature on Thermal Stability and Hardness of Nanocrystalline Cocrfeni High Entropy Alloy

Role of Yttrium Addition and Annealing Temperature on Thermal Stability and Hardness of Nanocrystalline Cocrfeni High Entropy Alloy

Impact of substrate temperature of yttrium doped NiAl bond coat fabricated by using EBPVD on inconel 625

The bond coat has been developed on Inconel 625 substrate by using Electron Beam Physical Vapour deposition (EBPVD) method at different substrate temperatures (ie. 873 K and 973 K). Intended for this persistence, the composition of Ni-49.8Al-0.2Y bond coat pellet was prepared. Structural information, Roughness, Morphology of coating have been characterized by using X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), and Field Emission Scanning Electron Microscopy (FESEM) respectively. Finally, the Coefficient of Thermal Expansion (CTE) is measured by using Dilatometer. Observed that the crystallinity was increased from 29.43 nm to 37.33 nm with increasing the substrate temperature. Also verified peak expansion is decreasing due to increase in substrate temperature. The average roughness increases to 17%. Columnar structure is observed at higher substrate temperature (973 K) of bond coat surface. The CTE of 973 K substrate temperature coating has 1.27 × 10 −5 K −1 at 1000 °C which is increases 8% with the substrate (1.16 × 10 −5 K −1 at 1000 °C). This is accomplished due to addition of Yttrium to bond coat material. These coatings used in thermal barrier applications such as in gas turbines, jet engines, and power aircraft etc. • Yttrium doped NiAl bond coat is deposited by EB PVD method on Inconel 625 substrate with different substrate temperatures. • Phase analysis, Average surface roughness and Surface morphology is measured by XRD, AFM and FESEM. • The thermal expansion coefficient is increased to 8% higher than the Inconel 625 substrate to bond coating (973 K).

Fabrication of stable monoclinic zirconia-based ceramics

Recently ZrO2 -based ceramics gained attention due to their shape memory properties. In order to use the power of shape recovery in shape memory materials, it is essential to access the twinned low symmetry phase in the temperature regime of the desired application. However, creating stable monoclinic phase is difficult in bulk ZrO2 due to volume expansion during phase transformations after sintering. Therefore, the material is often stabilized in the tetragonal phase by addition of yttria, which leads to transformation temperatures far below room temperature. In this article, we describe the sintering temperature and time as well as pre-processing steps for a successful formation of a stable, twinned monoclinic phase at room temperature in bulk ceramic 1-x Y0.5Ta0.5O2 + x Zr0.5Hf0.5O2 (0.6 < x ≤ 1).