Effect Of Zr Content Research Articles

Investigation on microstructure, mechanical properties and work hardening behavior of as-extruded Mg-4.5Zn-0.75Y-xZr alloys

The effects of Zr content on microstructures, mechanical properties and work hardening behavior of the as-extruded Mg-4.5Zn-0.75Y-xZr (x = 0.14, 0.28, 0.42, in at%) alloys were investigated with the assistance of optical microscope (OM), x-ray diffraction (XRD), scanning electron microscope (SEM) and material testing machine. The results show that the matrix microstructures of the as-extruded Mg-4.5Zn-0.75Y-xZr alloys present as typical bimodal structures, which are characterized by coarse α-Mg grains surrounded by many relatively fine dynamically recrystallized grains. The average grain sizes (GSs) of the extruded alloys show a trend of first decreasing and then slightly increasing with increasing Zr content, but the I-phase (Mg3Zn6Y) volume fractions keep almost constant. Among the three alloys, Mg-4.5Zn-0.75Y-0.28Zr alloy exhibits the optimum comprehensive mechanical properties (the ultimate tensile strength, yield strength and elongation to failure are 353 MPa, 296 MPa and 26.5%, respectively), which is corresponded to its smallest average GS. Meanwhile, with the reduction of the average GS, the work hardening (WH) rate, hardening capacity and WH exponent of the extruded alloys decrease. The WH rate decreases linearly with increasing deformation at the third stage of WH. Moreover, all the studied alloys show good ductility, and their ductile fracture features can be observed from the morphologies of tensile fracture surfaces at room temperature.

Influence of Zr dopant on polarization in rutile (In0.5Nb0.5)0.005(Ti1‐xZrx)0.995O2 ceramics

Abstract(In0.5Nb0.5)0.005(Ti1‐xZrx)0.995O2 (INZT, x = 0‐0.10) ceramics were synthesized using a conventional sintering method, and the effects of Zr content on the microstructures, dielectric properties and electron‐pinned defect‐dipoles (EPDD) polarization of the resultant products were investigated. The solubility limit of INZT was x = 0.075, and a secondary ZrTiO4 phase appeared at x = 0.10. Ceramics with x = 0‐0.10 exhibited excellent dielectric properties, ie, colossal permittivity (CP, εʹ > 103) and low dielectric loss (tanδ < 0.1), over a wide range of frequencies (100‐106 Hz at 300 K) and temperatures (50‐350 K at 1 kHz). The dielectric spectra and XPS results confirmed that the CP property of the ceramics could be ascribed to their EPDD polarization. The activation energy (Ea) for EPDD polarization was continuously enhanced by increasing x values. EPDD relaxation parameters at different x values were revealed using Cole‐Cole equation fitting. Moreover, α, which characterize the relaxation time τ distribution, increased with x values, thus indicating that Zr was involved in and affected electron localized states. The high Ea, temperature Tp of the peak εʹʹ at 1 kHz, and dielectric relaxation time τp at 30 K were related to increases in hopping distance of electrons among defect clusters with Zr addition.

Effects of Zr, Y on the Microstructure and Properties of As-Cast Cu-0.5Y-xZr (wt.%) Alloys

In this paper, the microstructure and properties of as-cast Cu-Y-Zr alloys with different Zr content were studied in order to investigate whether the precipitates in copper alloys would interact with each other by adding Y and Zr simultaneously. As-cast Cu-0.5Y-xZr (wt.%, x = 0.05 and 0.1, nominal composition) alloys were prepared by vacuum melting in this study. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to observe the microstructure of the alloys. The mechanical properties of the alloys were tested by universal material testing machine at room temperature. The effects of Zr content on the microstructure and mechanical properties of the alloys were explored. As shown by the research results, in the as-cast Cu-0.5Y-xZr (wt.%) alloys, the precipitated phase was the Cu5Y/Cu5Zr phase and ranged from 10 nm to 70 nm in size; when the Zr content increased from 0.05 wt.% to 0.1 wt.%, both the tensile strength and elongation rate of the alloys increased; when the Zr content was 0.1 wt.%, the tensile strength was 225 MPa and the elongation rate was 22.5%.

Self-organized TiO2 nanotube layer on Ti–Nb–Zr alloys: growth, characterization, and effect on corrosion behavior

Ti alloys are widely applied in implanted biomedical devices due to their unique mechanical and biological performances. A strategy employed to improve bone integration on orthopedic and dental implants is to grow a self-organized TiO2 nanotube layer on the surface of titanium alloy implants. This paper describes the formation of self-organized TiO2 nanotubes on Ti–35Nb–2Zr and Ti–35Nb–4Zr alloys by the anodization process, as well as the effects of Zr content on TiO2 phase stability. The morphological and chemical characteristics of the nanotubes were analyzed by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron microscopy. In addition, a comparison was made of the electrochemical stabilities of TiO2 nanotube-coated surfaces and surfaces without nanotubes, which revealed higher corrosion resistance for the nanotube-modified surface. The electrochemical impedance spectroscopy results were fitted with two-time constant equivalent circuit representing the barrier layer (nanotube bottom) and the porous layer (nanotube wall). The addition of Zr suppressed ω-phase formation, preserving the alloy’s low elastic modulus (64 GPa). This Zr addition also delayed the anatase-to-rutile transformation and slightly increased the nanotubes’ length to 1.14 µm. These features make the Ti–35Nb–4Zr alloy a very good candidate for use in the biomedical field, especially for applications that require low elastic modulus with enhanced corrosion resistance.

Effect of Zr Content on the Activity of 5%СuO/Ce1– xZrxO2 Catalysts in CO Oxidation by Oxygen in the Excess of Hydrogen

The article reports the synthesis of 5%CuO/Ce1– xZrxO2 catalysts based on CeO2, ZrO2 oxides and Ce1– xZrxO2 solid solutions with х = 0.2, 0.5, and 0.8. It is found that copper oxide is present in the catalysts in a highly dispersed form. In strong interaction with supports, it forms active oxygen, which participates in CO chemisorption and low-temperature oxidation of CO in the presence of hydrogen. In selective CO oxidation, the highest conversion (γmах = 100%) was obtained at temperatures of 120–160°С in the presence of 5%CuO/CeO2. In the modification of CeO2 by zirconium cations, the conversion on 5%Ce0.5Zr0.5O2 decreases to 92% at 160°С because oxygen binding strengthens on copper-containing sites. On the 5%CuO/ZrO2 sample, the maximum conversion is 67% at 180°С. The modification of ZrO2 by cerium cations leads to an increase in the conversion to 87% at 160°С on the 5%CuO/Ce0.2Zr0.8O2 sample as a result of increasing the amount of oxygen vacancies in the support. Taking into account the properties of CO complexes formed on copper-containing oxidation and adsorption sites, and the interaction of these complexes with adsorbed oxygen, their participation in the reaction of low-temperature CO oxidation by oxygen in excess of hydrogen on 5%CuO/CeO2 and 5%CuO/ZrO2 catalysts is considered.

Interfacial microstructure and mechanical property of ZrC-SiC ceramic and TiAl joint brazed with Ag[sbnd]Zr active filler metal

Reliable brazing of ZrC-SiC ceramic and TiAl alloy was achieved using active AgZr filler metal. During the brazing process, Ti and Al were dissolved into the filler metal, and TiC+(Ti,Zr)3SiC2 layer formed due to the reaction between the ZrC-SiC and Ti. Meanwhile, strong affinity of Ti, Al and Zr produced dispersive (Ti,Zr)(Al,Ag) in the brazing seam. The effect of Zr content and holding time on the microstructure and mechanical property of the joints was investigated. With the increase of Zr content, the formation of (Ti,Zr)(Al,Ag) phase was promoted and its volume became large. The consumption of Ti in (Ti,Zr)(Al,Ag) phase restrained the formation of TiC, decreasing the thickness of TiC layer. Excess Zr addition could induce large bulks of (Ti,Zr)(Al,Ag) and cracks in the brazing seam. The holding time mainly affected the distribution of Ti-Zr-Al-Ag phases in the brazing seam. The joint strength reached a maximum value of 65 MPa when the Zr content of the filler was 5 wt% and holding time was 5 min. The crack propagated in the ZrC-SiC ceramic substrate.

Effect of Zr content on structure and mechanical properties of (CrTaNbMoV)Zrx high-entropy alloy films

In this paper, the influence of Zr content on the phase formation, morphology, hardness and tribology behavior of (CrTaNbMoV)Zrx films are systematically investigated. The XRD results indicate that the (CrTaNbMoV)Zrx films are evolved from BCC to amorphous phase. The thermodynamic ΔSmix, ΔHmix and VEC of amorphous are similar to BCC structure, while the atomic radius mismatch (δ) of amorphous phase is remarkable large that the values of BCC phase. FESEM shows that the top surface grain size is decreased and the cross-section becomes much denser and compacted with increasing Zr content. With an increase of the Zr content in the films, the hardness and modulus are slightly increased and reaches maximum values of 11.6 GPa and 215.6 GPa, respectively. The friction coefficient and wear rate are decreased with increasing of Zr content and the wear rate of Zr content with 30.07 at% decreases 25% that the film without Zr addition.

Effect of Zr doping and lattice oxygen release on the resistive switching properties of ZrxHf1−xO2-based metal-oxide-semiconductor devices

The effect of Zr content on resistive switching properties of ZrxHf1–xO2-based metal-oxide-semiconductor (MOS) devices has been studied. The electrical characteristics and x-ray photoelectron spectroscopy studies reveal that the resistive switching property performs its best when the Zr content in the film is 9.11%. The XPS data reveals presence of non-lattice oxygen in all the devices. The differential scanning calorimetry (DSC) study shows an endotherm peak at ~ 145.9 °C only for the sample at a particular Zr content in the ZrxHf1–xO2 film indicating release of lattice oxygen. Thus, besides presence of non-lattice oxygen in the film, further generation of hole trap density in the form of lattice oxygen release is required to achieve a better low resistance state (LRS) and the same is reflected in the double logarithmic plot of I − V. It is believed that some sort of microstructural arrangements take place at a critical Zr content that lead to the lowest resistive state of the MOS device.

The effect of Zr content on the thermal stability, dielectric and pyroelectric behavior for lead zirconate prepared by tartrate precursor method

The series of lead titanate with various concentration of zirconium PbZrxTi1−xO3 (PZTO), where (x = 0, 0.2, 0.4 and 0.8), have been prepared successfully by tartrate precursor method and then annealed at 1273 K in atmospheric pressure. The results showed that PZTO samples with varying composition (x) have highly phase purity and crystallized perovskite structure without pyrochlore phase in every composition. The grains of prepared samples are densely packed with few pores and the grain size increases with Zr content. The results showed also the thermal stability of PbZr0.8Ti0.2O3 sample is higher remarkably compared to other samples with lower Zr concentration which is enhanced remarkably with Zr content. The DC resistivity and dielectric behaviors indicate that the phase transition in all the samples is diffused type. It is observed that saturation polarization and coercive field have increased with high Zr content samples (x = 0.4 and 0.8). On the contrary, the remanent polarization has decreased slightly with high Zr content samples. Furthermore, there is a remarkable enhancement of the pyroelectric voltage for PZTO with high Zr content samples (x = 0.4 and 0.8). Therefore, it is recommended that these prepared samples are preferable for use in pyroelectric detector applications such as infrared sensors, infrared thermometers, and laser energy sensors.

Effect of Zr content on the structure and oxidation resistance of silicide coatings prepared by pack cementation technique

Modified silicide coatings were prepared on Ti-5Al-10Nb-xZr (x = 0, 2, 5, 10, 15 and 20 at.%) alloys by pack cementation process. The effects of Zr content on the coating structure and oxidation resistance have been investigated. With increasing Zr contents in the substrate, the coating structure shows a significant change. Adding 2 at.% Zr can improve the oxidation resistance of silicide coating due to the formation of a thin and dense SiO2 layer. But excessive Zr exerts an adverse influence on the oxidation resistance due to the volume expansion caused by the phase transformation of ZrO2 during the oxidation process.

Effect of Zr content on structure property relations of Ni-Zr alloy thin films with mixed nanocrystalline and amorphous structure

A comparative study has been carried out on microstructural evolution, surface roughness, nanoindentation and scratch behavior, electrical resistivity, and corrosion resistance of Ni1-xZrx (0.13 ≤ x ≤ 0.40) thin films deposited on Si-(100) substrate by DC magnetron co-sputtering of high purity elemental targets in argon atmosphere. The film compositions have been examined by energy dispersive X-ray and Auger electron spectroscopy. Grazing incidence X-ray diffraction (GIXRD) studies have shown presence of Ni-rich solid solution, Ni3Zr and amorphous phase in all the films, with Ni5Zr being additionally observed in the Ni87Zr13 film. Analysis of GIXRD data along with transmission electron microscopic studies have shown that volume fractions of both amorphous phase and Ni3Zr are increased, whereas the average crystallite size is decreased with increase in Zr concentration. Nanoindentation hardness and Young's modulus as well as electrical resistivity measured by Van-der Pauw four-probe method are influenced by volume fractions of both Ni3Zr and amorphous phase. Surface roughness and coefficient of friction obtained from atomic force microscopy and nano-scratch experiments, respectively decrease, whereas corrosion resistance in 3.5 wt% NaCl solution increase with Zr concentration primarily due to increase in amorphous phase content. Resistance to pitting corrosion is facilitated by formation of ZrO2-rich passive film, as confirmed by X-ray photoelectron spectroscopy.

Effect of Zr on magnetic properties and electrical resistivity of Sm(CobalFe0.09Cu0.09Zrx)7.68 magnets

In this work, the effect of Zr content on magnetic properties and electrical resistivity of Sm(CobalFe0.09Cu0.09Zrx)7.68 (x = 0.020, 0.025, 0.030, 0.035) high temperature magnets has been investigated. More Zr content results in the decrease of average cell size and the increase of the density of lamellar structure. In addition, a large number of phase boundaries between lamellar phase and cellular structure have also been formed. The intrinsic coercivity of 550 °C enhances from 3.21 kOe to 6.05 kOe with the increase of Zr content. Furthermore, electrical resistivity shows obviously different variation in different directions with increasing Zr content. At room temperature and 127 °C, the electrical resistivity improves from 68.2 μΩ cm to 91.7 μΩ cm and from 87.1 μΩ cm to 103.3 μΩ cm with increasing x from 0.020 to 0.035 in the direction parallel to c-axis, respectively. However, there is only a slight increase in the electrical resistivity in the direction perpendicular to c-axis. The rise of electrical resistivity in different directions has been discussed. Research results indicate that increasing the density of the lamellar phase is an effective way to increase electrical resistivity in the 2:17-type Sm-Co magnets.

Influence of Zr addition on the corrosion behavior of biomedical PIM Ti-16Nb alloy in SBF

Abstract In this study, the effect of Zr content on the corrosion resistance of Ti-16Nb alloy produced by powder injection molding was investigated. Electrochemical corrosion tests were carried out in simulated body fluid using electrochemical impedance spectroscopy and polarization curve analysis. It is observed that, with the addition of 10 wt.% Zr to the base alloy, the corrosion current density and the corrosion rate decreased from 2.23 to 1.55 μA cm−2 and 961.7 × 10−3 mpy to 703 × 10−3 mpy, respectively. As a result, the addition of Zr has been effective in increasing the corrosion resistance of the Ti16Nb alloy.

The effects of Zr contents on microstructure and properties of laser additive manufactured Ti-6.5Al-3.5Mo-0.3Si-xZr alloys

A new type of Ti-6.5Al-3.5Mo-0.3Si-xZr (x = 1.5, 2.5, 3.5, 4.5 wt%) titanium alloys developed on TC11 alloy (x = 1.5) with different Zr contents were fabricated by laser additive manufacturing process in order to enhance the mechanical properties. Grain morphology and microstructure were systematically investigated. The results demonstrate that the addition of Zr element dramatically refines the grains of the titanium alloys by offering heterogeneous nucleate sites and controlling grain growth during subsequent thermal cycles. And the latter is the main influencing factor. Meanwhile, the addition of Zr element in the alloys does not affect their microstructures, which with similar α lamellar thickness. And the microhardness and compressive strength of the alloys continuously increase with the increase of Zr contents.

Effects of Zr Content on the Bending Property and Crystallization Behavior of Ductile Zr-Based Bulk Metallic Glasses

In this study, the effects of Zr content on the bending property, non–isothermal and isothermal crystallization kinetics of high–Zr–based BMGs were investigated. The BMGs exhibit high bending strength and their bending plasticity enhances with increasing Zr content, which is due to more free volume with high–Zr–content. During continuous heating, the crystallization phases for Zr66 and Zr70 BMGs are Zr2Cu and Zr2Ni phases. Zr70 alloy exhibits the highest activation energies for glass transition and crystallization because of the sluggish diffusion of large Zr atoms. Under isothermal condition, the average Avrami exponent of Zr66 alloy modeled by the JMA equation is about 2.6, implying a diffusion–controlled three dimensional crystallization growth with an increasing nucleation rate. The average Avrami exponent of 2.0 for Zr70 alloy indicates a diffusion–controlled three dimensional crystallization growth with a decreasing nucleation rate, which can be attributed to its higher activation energy for crystallization.

Effects of Zr Contents on the Microstructure, Mechanical Properties and Biocompatibility of Ta-Zr Alloys

Ta-xZr (x = 90, 80, 70, 60 at.%) alloys with good mechanical properties and high density were prepared by powder metallurgy method and vacuum sintering technology. The surface morphologies and mechanical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS). The results showed that lamellar Ta was observed with no second phase during the sintering process. The tensile strength and the Young's modulus increased with the Ta contents firstly and then decreased, and varied with the Ta contents in the range of 60.5 ± 5.03~163.0 ± 10.11 MPa and 4.5 ± 0.47~11.8 ± 1.16 GPa, respectively. In conclusion, The Ta-70Zr alloy is potentially useful in the hard tissue implants for its mechanical properties and biocompatibility.

Effect of Zr content on damping property of Mg–Zr binary alloys

The damping property expressed by internal friction tan⁡φ of as-cast Mg–Zr binary alloys with Zr content from 0.6 to 5.0% was experimentally measured under conditions of changing temperature from ambient temperature Tam to 600 K (327 °C), vibration frequency f from 1.0 to 10.0 Hz, strain ε from 1.0 × 10–6 to 1.0 × 10–3, and heating rate ν from 2 to 5 K/min. The experimental results indicate that the damping property of prepared as-cast Mg–Zr binary alloys can be effectively promoted by increasing either heating rate ν or strain ε. Increasing vibration frequency f can effectively decrease the damping property, however increasing vibration frequency f has little effect on the plots of internal friction tan⁡φ against temperature T, i.e., T–tanφ curve, under the condition of f > 5.0 Hz. The optimal Zr content of the as-cast Mg–Zr binary alloys with better performance of damping property is recommended to be 0.6 mass % in a range of Zr content from 0.6 to 5.0%. Furthermore, the effect of strain ε on damping property for the as-cast Mg–Zr binary alloys can be ideally explained by dislocation pinning theory or the G–L model, while the influence of temperature T on damping property for the as-cast Mg–Zr binary alloys complies with the viscoelastic relaxation behaviour.

Effect of Zr Content on Mechanical Properties of Diamond/Cu-Zr Composites Produced by Gas Pressure Infiltration

Diamond particle-reinforced Zr-alloyed Cu matrix (diamond/Cu-xZr) composites were produced by a gas pressure infiltration route, with x = 0.0, 0.3, 0.5, 0.75, and 1.0 wt.%. The x-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterization confirms the formation of ZrC at the diamond/Cu interface. With increasing Zr content, the tensile, bending, and compressive strengths of the diamond/Cu-Zr composites are found to firstly increase and then decrease. The maximum tensile, bending, and compressive strengths at 0.75 wt.% Zr are 108, 360, and 441 MPa, respectively. The variation of the mechanical properties is attributed to the formation of interfacial ZrC. The increase in amount of ZrC strengthens the interface, but large ZrC particles formed at high Zr content are harmful to the interfacial bonding. The result suggests that the mechanical properties of diamond/Cu composites can be enhanced by Cu matrix alloying with Zr.

Effect of Zr content on friction and wear behavior of Cr‐Zr‐N coating system

AbstractNanostructured Cr‐Zr‐N thin film with different Zr content (0 to 48.8 at.%) was deposited, using an RF magnetron‐sputtering technique. The structural evolution and morphological changes were performed. The tribological performances were evaluated, using a ball‐on‐disk type Oscillating tribometer. The tests were carried out under normal loads of 2, 4 and 6 N, respectively, with an alumina ball (Al2O3) as a counter face. The results showed that the crystallite size of the Cr‐Zr‐N system was reduced to 10.8 nm at 31.8 at.% Zr content. Morphological studies of the films showed that the roughness continuously decreased with increasing Zr content, exhibiting a value of 11.2 nm at 31.8 at.% Zr. The wear rate tends to decrease with the increasing of Zr content to reach a lowest value of 1.95 × 10‐2 μm3.N.μm‐1 at 31.8 at.% Zr. The wear rate and friction coefficient were lower in the samples with 31.8 at.% Zr content. The improved friction and wear resistance were attributed to the grain refinement strengthening mechanism at 31.8 at.% of Zr.

Study in Wire Feedability-Related Properties of Al-5Mg Solid Wire Electrodes Bearing Zr for High-Speed Train

This work offers an analysis of the wire feedability-related properties of Al-5Mg solid wire electrodes bearing Zr. Effects of Zr content on microstructures and mechanical properties of the Al-5Mg alloys were studied. Experimental results have demonstrated that α-Al dendrites of the as-cast Al-5Mg alloy are refined, and the tensile strength, microhardness and roughness of the 1.2 mm wire electrode are improved with an appropriate addition of Zr. In addition, the tensile strength and elongation of the welded joints welded using Al-5Mg wire electrodes bearing Zr reach the maximum value when 0.12% Zr is added into the wire alloy. However, when excess Zr is added, α-Al phases of the wire alloy and welded joint are coarsened, and the mechanical properties are deteriorated. Moreover, the structure and principle of a novel apparatus, which can enhance the feedability of the wire electrode, are introduced and the apparatus can achieve the rough and fine adjustments of cast and helix of the wire electrode.