Effect Of Yttrium Addition Research Articles

Effects of amorphous phase and yttrium on flash sintering and microstructures of ZrO2–SiO2 ceramic nanocomposites

AbstractFlash sintering has been used to consolidate a wide range of ceramics and ceramic composites. However, flash sintering of ceramic nanocomposite with a substantial amorphous phase is rarely studied. Meanwhile, the effects of yttrium addition on the flash sintering behaviors and microstructures of ZrO2‐based ceramic nanocomposite remain unknown. Herein, ZrO2‐SiO2 crystalline‐amorphous ceramic nanocomposites (CACNs) with different contents of amorphous phase and two types of yttrium dopants were sintered by flash sintering. Results showed that the content of amorphous phase (SiO2) had significant effects on the flash sintering behavior. The CACN with 65 mol% SiO2 was nonflash sinterable due to the high electric resistivity of SiO2, whereas, the CACN with 45 mol% SiO2 can be flash sintered to high densification within 35 seconds. The flash‐sintered CACNs consisted of ZrO2 nanocrystallites distributed in an amorphous SiO2 matrix. Flash sintering enhanced the tetragonal‐to‐monoclinic phase transformation of ZrO2. In addition, influences of yttrium dopant on CACNs were also investigated. Yttrium dopants can rapidly dissolve in ZrO2 lattices and show a tetragonal phase stabilization effect during flash sintering. Firework‐like ZrO2 microcrystallites formed by dendritic growth were observed close to the cathode region, which was attributed to athermal electric field effects and the formation and aggregation of oxygen vacancies at the cathode region. The results would provide guidance for fabricating CACNs via flash sintering.

Effects of Yttrium Addition on Bending Deformation Behavior of Magnesium

Effects of Yttrium Addition on Bending Deformation Behavior of Magnesium

Improved hardness of Mg-0.5Ni-xY alloys via grain refinement and formation of LPSO structures

The effect of yttrium addition on the grain refinement, formation of long period stacking ordered (LPSO) structures, and improved hardness in hot extruded Mg99.5-xNi0.5Yx (x = 0, 0.5, and 1 at%) alloys was investigated. It was revealed that with increasing Y content, the volume fraction of the LPSO phase (VLPSO) increased, and the average dynamic recrystallization (DRX) grain size (D) was refined. It was shown and quantified that both VLPSO and D contribute to the improvement of hardness, where the deviation from the Hall-Petch relationship was ascribed to the strengthening effect of VLPSO. The equation of H = 36.7 + 0.64 VLPSO + 35/√D was proposed to quantify the synergistic effects of hardening mechanisms to predict the hardness of Mg99.5-xNi0.5Yx alloys after deformation by hot extrusion.

Tailoring the microstructure and mechanical properties of LPSO-containing Mg–Ni cast alloy by yttrium addition

The effect of yttrium addition on the evolution of phases, grain refinement, and mechanical behavior of Mg-0.5Ni cast alloy was investigated. It was observed that while the base alloy contained a eutectic structure containing α-Mg and Mg2Ni, in the Y-containing alloys, the long period stacking ordered (LPSO) structures and Mg24Y5 phase appeared at the expense of the eutectic structure. The dendrite arm spacing (DAS) was significantly refined, so that adding 0.5 and 2 at% Y led to the refinement of DAS from 141 to 56 and 22 μm, respectively. Accordingly, hardness, tensile and shear strength were improved, being successfully represented by the Hall-Petch-type relationships in terms of DAS. The highest elongation to failure in tensile tests was obtained at 0.5 % Y addition, which was ascribed to the refinement of microstructure and partial replacement of the deleterious α-Mg + Mg2Ni eutectic structure by the LPSO phase. However, further addition of Y led to the formation of intergranular interconnected network of LPSO structure with deteriorated ductility. Therefore, the best strength-ductility synergy was obtained for the Mg99Ni0.5Y0.5 alloy, as evaluated by the tensile toughness. Finally, the tensile and shear properties were correlated according to the von-Mises criterion.

Effect of yttrium addition on precipitated phase, corrosion resistance, and mechanical behavior of 6Mo superaustenitic stainless steel

Optimizing alloy composition is an effective method to regulate the microstructure and improve the properties of superaustenitic stainless steel (SASS). In this research, 6Mo SASS containing 16 ppm and 83 ppm yttrium (Y) was prepared, and the effects of Y microalloying on secondary phase precipitation and materials performance were investigated. It was found that higher Y content could better inhibit the sigma(σ) and Cr2N phase precipitation along the grain boundary, leading to the improvement of the intergranular corrosion (IGC) resistance and mechanical properties of aged steels.

The Effect of Yttrium Addition on Microstructure and Mechanical Properties of Refractory TiTaZrHfW High-Entropy Films

Refractory high-entropy films (RHEFs) are a new type of high-temperature material with great prospects for applications due to their superior properties. They have the potential to replace nickel-based superalloys in order to develop a new generation of materials that can be used under extreme conditions. (TiTaZrHf)100−xYx RHEFs are prepared using the magnetron sputtering technique. The yttrium (Y) content varies from 0 to 56 at.%. XRD analysis indicates the formation of an amorphous phase in Y-free films, while new phases are formed after the addition of Y. The results are confirmed by TEM analysis, revealing the formation of nano-grains with two phases L12 and Y-P6/mmm structure. With an increasing Y content, the grain size of the nano-grains increases, which has a significant effect on the mechanical properties of the films. Hardness decreases from 9.7 GPa to 5 GPa when the Y amount increases. A similar trend is observed for the Young’s modulus, ranging from 111.6 to 82 GPa. A smooth and featureless morphology is observed on the low Y content films, while those with a larger Y content appear columnar near the substrate. Furthermore, the phase evolution is evaluated by calculating the thermodynamic criteria ΔHmix, ΔSmix, Ω, and δ. The calculation results predict the formation of new phases and are then in good agreement with the experimental characterization.

Effect of Yttrium Addition on Nonmetallic Inclusions in FeCrAl Alloys

To investigate the effect of yttrium (Y) addition on nonmetallic inclusions in FeCrAl alloys, a series of laboratory experiments and thermodynamic calculations are carried out as a function of reaction time and Y addition amount. Without Y addition, the main inclusion in FeCrAl alloys is AlN, and only a small amount of Al2O3 inclusions is evident. The higher content of Cr in FeCrAl alloy promotes the formation of Al2O3. Y addition can effectively modify Al2O3 inclusions to YAlO3 or YS inclusions. With the addition of 0.0046 wt% Y, the evolution route of inclusions in FeCrAl alloys with reaction time is Al2O3 → YAlO3‐Al2O3 → YAlO3. The variation in Al2O3 inclusions with increasing Y content is Al2O3 →YAlO3 → YS. The experimental results are consistent well with the thermodynamic calculation results.

Effect of yttrium addition on microstructural evolution and high temperature mechanical properties of Ni-based superalloy produced by selective laser melting

The effects of Y addition on the microstructural evolution and room/high temperature mechanical properties of SLM Ni-based superalloy were investigated. Y-free and Y-added SLM Ni-based superalloy as two alloys for comparison. In the Y-added superalloy, the main reasons for the denser microstructure are a flat melt pool and epitaxial growth of columnar dendrites with <001> orientation. Moreover, the Y-added SLM specimens have superior hot tensile performance due to high density dislocation and the formation of Y2O3-oxides. Analysis of microstructural evolution under elevated temperatures showed that the interaction between dislocation and oxide could pin dislocation at the grain boundary and increase the annihilation temperature of dislocation. We also examined the high temperature fracture morphology of Y-added specimens, and found that their excellent performance is primarily because of tenacity nests and serpentine sliding originating from the oxide and dislocation, as well as their impediment to microvoid extension.

Effect of yttrium addition on phase transformations in alloy 718

The nickel-base alloy 718 is widely used due to its superior performance at high temperatures, combining properties such as high strength, high corrosion and oxidation resistances and good formability and weldability. Its properties can be further improved by controlled additions of alloying elements such as Ce, W, Mo, P, B and Y. The present work aims to evaluate the effect of the yttrium alloying on the phase transformation in alloy 718. Thermodynamic calculation, scanning electron microscopy, electron backscattered diffraction, hardness measurements and differential scanning calorimetry tests were conducted. The Ni17Y2 phase was observed in two situations: associated with the Nb-rich particles or as single particles. The addition of yttrium has a remarkable effect on grain size control. The differential scanning calorimetry tests indicated that the alloy with the high Y content showed earlier precipitation of the γ” phase (Ni3Nb), which is the main hardening contributor, resulting in an increase in hardness.

Effects of yttrium addition on microstructures and mechanical properties of CoCrNi medium entropy alloy

Element addition is an effective way to improve the properties of alloys. In this work, (CoCrNi)100-xYx (x = 0, 0.1, 0.3, 0.7 and 1.0, named Y-0, Y-0.1, Y-0.3, Y-0.7 and Y-1.0 accordingly) medium entropy alloys (MEAs) were fabricated by arc melting, and the effects of yttrium addition on the microstructures and mechanical properties of CoCrNi MEAs were studied. For Y-0 and Y-0.1, the alloys remained an FCC solid solution. Due to the most negative mixing enthalpy of Y–Ni element pair in the alloy, the HCP YNi5 precipitates formed in Y-0.3, and the volume fraction of precipitates increased with the increasing Y content. Both Y in the solid solution matrix and YNi5 precipitates resulted in grain refinement, and the grain size decreased with the increasing Y content. Annealing twins were observed; however, the twin boundary fraction showed only slight increase with the increasing Y content (from 69.2% for Y-0 to 73.1% for Y-1.0). The nanoindentation tests showed that the hardness of the HCP precipitates was about two times of the FCC matrix. Compared to Y-0, Y-0.1 showed only slight improvements in microhardness and tensile strength. However, in the presence of precipitates, the microhardness, yield strength and tensile strength showed significant enhancements with the increasing Y content in the alloy. Both the microhardness and strength scaled with the volume fraction of precipitates in the alloy. While precipitation strengthening had the major contribution, both the solid solution strengthening and grain boundary strengthening had only the minor contribution to our system.

Effect of Heat Treatment on Microstructure and Dimensional Stability of Y-Modified AlSi7Cu3Mg Alloy

The application of rare earth modified AlSi7Cu3Mg alloy in automobile engine and motor casing has increased. The dimensional stability of this alloy is an important feature. In this paper, the effects of yttrium addition and different heat treatment on the microstructure and dimensional thermal stability of AlSi7Cu3Mg alloy were studied by OM, SEM and dimensional measurement. Research shows that: The dimensional stability of AiSi7Cu3Mg alloy after T6 heat treatment is better than that after T4 heat treatment, and the dimensional stability after T7 heat treatment is the best. The addition of rare earth Y can improve the dimensional stability of AiSi7Cu3Mg alloy.

Effect of Yttrium Addition on Structure and Magnetic Properties of Co60Fe20Y20 Thin Films.

In this paper, a Co60Fe20Y20 film was sputtered onto Si (100) substrates with thicknesses ranging from 10 to 50 nm under four conditions to investigate the structure, magnetic properties, and surface energy. Under four conditions, the crystal structure of the CoFeY films was found to be amorphous by an X-ray diffraction analyzer (XRD), suggesting that yttrium (Y) added into CoFe films and can be refined in grain size and insufficient annealing temperatures do not induce enough thermal driving force to support grain growth. The saturation magnetization (MS) and low-frequency alternate-current magnetic susceptibility (χac) increased with the increase of the thicknesses and annealing temperatures, indicating the thickness effect and Y can be refined grain size and improved ferromagnetic spin exchange coupling. The highest Ms and χac values of the Co60Fe20Y20 films were 883 emu/cm3 and 0.26 when the annealed temperature was 300 °C and the thickness was 50 nm. The optimal resonance frequency (fres) was 50 Hz with the maximum χac value, indicating it could be used at a low frequency range. Moreover, the surface energy increased with the increase of the thickness and annealing temperature. The maximum surface energy of the annealed 300 °C film was 30.02 mJ/mm2 at 50 nm. Based on the magnetic and surface energy results, the optimal thickness was 50 nm annealed at 300 °C, which has the highest Ms, χac, and a strong adhesion, which can be as a free or pinned layer that could be combined with the magnetic tunneling layer and applied in magnetic fields.

Effects of yttrium addition on microstructure and mechanical properties of Inconel 718 alloy produced by sub-rapid solidification

In order to improve the mechanical properties of Inconel 718 alloy produced by sub-rapid solidification, the yttrium (Y) element was added during casting. One alloy with 0.1% weight Y content (0.1Y) and a reference alloy without Y addition (0Y) were produced, which involved homogenization, cold rolling, intermediate annealing, and aging treatment. The influences of Y addition on the microstructure and mechanical properties of Inconel 718 alloy were examined. Due to the precipitation of Ni3Y and Ni17Y2 particles, 0.1Y alloy exhibited a refined grain size and a lower recrystallization fraction. The average grain size of 0Y homogenized sample and 0.1Y homogenized sample were about 50.8 μm and 29.5 μm, respectively. Besides, a higher fraction of δ phase precipitated in the 0.1Y annealed sample, including a large amount of granular or short-rod shape δ phases and a small amount of needle-like δ phases. The area fraction of δ phase in the 0.1Y annealed sample was ~10.45%. However, the area fraction of δ phase in the 0Y annealed sample was lower (~7.93%), and needle-like δ phase was hardly observed under this condition. Compared with 0Y alloy, 0.1Y alloy showed better tensile properties. The 0.1Y alloy after aging treatment exhibited an excellent combination of ultimate tensile strength (~1400 MPa), and total elongation (~20%) when deformed at room temperature.

The Effect of Yttrium Addition on the Microstructure and Irradiation Hardening in V-4Cr-4Ti Alloy under Self-Ion Irradiation

Microstructure and irradiation hardening of V-4Cr-4Ti alloys with different yttrium (Y) contents were studied by self-ion irradiation at 550 °C via TEM and nano-indentation test technology. The peak damage of the V-4Cr-4Ti-xY alloy (x = 0, 0.1, 0.5, and 1, wt.%) irradiated by 2.5 MeV self-ion (V2+) is 8 dpa. Dense dislocation loops were observed in all vanadium alloy samples after irradiation. With the increase of Y content, both average size and number density of dislocation loops using g = &lt;110&gt; near the pole [001] decreased, while the irradiation hardness increment first decreased and then increased. In order to better reduce the irradiation hardening, it is considered that the addition of 0.1 wt.% Y in V-4Cr-4Ti alloy is reasonable.

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.

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.

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

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

Effect of yttrium addition on the hot deformation behavior of Fe–6.5 wt%Si alloy

Due to its remarkable soft magnetic properties, the Fe–6.5 wt%Si alloy has shown potential in energy-saving and noise-reducing applications. However, the appearance of brittle-ordered structures hinders its production and utilization. It has been previously indicated that rare earth (RE) elements can be used as inclusion modificators as well as for purification of molten steel and microalloying. In the present work, the effects of yttrium (Y) on the hot deformation of the Fe–6.5 wt%Si alloy was studied by hot compression at temperatures of 600–900 °C at different strain rates. Moreover, the processing maps were established according to the dynamic materials models (DMM), which determined the range of optimal process conditions. The obtained results demonstrated that in the range of 600–900 °C, the activation energy for hot deformation of the Fe–6.5 wt%Si alloy was 428.68 kJ/mol, which is lower than that of the alloy containing 0.03 wt%Y (473.27 kJ/mol). It is speculated that Y decreases the unstable region and apparently reduces the occurrence of microcracks during the hot deformation process of the Fe–6.5 wt%Si alloy. In addition, the presence of this element leads to an increase in the dislocation density and causes segmentation of the ordered domain. Lastly, the addition of Y improves the ductility of the Fe–6.5 wt%Si alloy due to grain refinement and reduction of the ordered domain size.

Effect of yttrium addition on dynamic mechanical properties, microstructure, and fracture behavior of extrusion-shear ZC61 + xY (x = 0, 1, 2, 3) alloys

In this study, extrusion-shear ZC61 + xY (x = 0, 1, 2, 3) magnesium (Mg) alloys were prepared by a novel severe plastic deformation method, i.e., extrusion-shear, which integrates direct extrusion with equal channel angular pressing. The effect of yttrium (Y) addition on dynamic mechanical properties, microstructure, and fracture behavior of ZC61 + xY (x = 0, 1, 2, 3) alloys was investigated by Split-Hopkinson Pressure Bar setup under a strain rate of 2100 s−1 along extrusion direction. With the increase in the content of added Y from 0 to 3 wt%, due to the strengthening of secondary phases and grain refinement, the yield strength of Mg alloys was enhanced from 142 to 342 MPa, and the ultimate compression strength of Mg alloys was improved from 582 to 701 MPa. During dynamic compression, the <c + a > pyramidal slip and extension twinning were the dominant deformation modes, which coordinated plastic deformation of ZC61 + xY (x = 0, 1, 2, 3) alloys. Analysis of the fracture behavior of four Mg alloys samples indicated that the fracture mode of ZC61 alloy was the brittle and melt mixed-mode; however, the fracture behavior of ZC61 + xY (x = 1, 2, 3) alloys was the brittle and ductile mixed fracture. With the increase of Y content from 1 to 3 wt%, the absorption energy density was observably increased, which was mainly responsible for the change of fracture mode from brittle fracture to ductile fracture.