Zr Alloy Research Articles

Atom probe tomography of deuterium-charged optimised ZIRLO

AbstractThis study investigates the morphology and composition of hydrides in Optimized ZIRLO following electrochemical deuterium charging. Both ZrO and ZrDx phases were formed upon charging. The interfaces between these phases are investigated by using atom probe tomography aided by cryogenic sample transfer. The Ga and Sn have formed a “net”-like structure at the original atom probe specimen surface, which is assumed to be associated with the boundaries between individual hydride laths/needles, as it thought to have formed as these species were excluded from the hydrides. Calculation of the D/Zr ratio throughout the sample allows for identification of the ZrDx phases, revealing the specimen consists of a complex arrangement of different hydride phases. In some areas there is small excess of D in the hydride, i.e. ZrD2+y. This result is interpreted as deuterium which was “frozen” as it was passing through the hydride during electrochemical charging. The observed microstructural changes and interfacial phenomena contribute valuable insights that may prove useful for improving the performance and safety of Zr alloys.

Unveiling the interaction between corrosion products and oxygen reduction on the corrosion of Mg–4Nd–0.4Zr alloy under thin electrolyte layers

Although hydrogen evolution reaction (HER) is considered to be the main cathodic reaction of Mg corrosion, oxygen reduction reaction (ORR) has been recently confirmed to be a secondary cathodic reaction. The factors affecting ORR of magnesium (Mg) alloys are still unclear, especially in cases under thin electrolyte layers (TEL). In this work, the influence of the corrosion product films on the cathodic reactions of Mg alloys under TEL and in a bulk solution was investigated. ORR does not influence the hydrogen evolution rates in the corrosion of Mg alloys. Therefore, with the existence of oxygen, corrosion rates of Mg alloys measured by hydrogen evolution tests are not accurate under TEL. And weight loss test is a more accurate method to evaluate Mg corrosion rates under TEL. ORR was confirmed to participate in the corrosion of Mg–4Nd–0.4Zr, Mg–4Nd and Mg–0.4Zr alloys under TEL. In 100-μm TEL, the highest contribution of ORR in cathodic reactions for the corrosion of Mg–4Nd–0.4Zr, Mg–4Nd and Mg–0.4Zr alloys are 28.6%, 39.1%, and 35.8%, respectively. The more protective film on Mg–4Nd–0.4Zr alloy provides a stronger inhibition effect against the diffusion of oxygen, leading to decreased ORR contribution in cathodic reactions. In addition, it is suggested that the preparation of Mg alloys with protective corrosion product films can inhibit the corrosion induced by ORR in the atmosphere. This work emphasizes the effects of corrosion product films on ORR in Mg corrosion, especially under TEL.

Achieving high strength-ductility synergy in Mg-Gd-Zn-Zr alloy by controlling extrusion processes parameters

The high rare earth content in current magnesium alloys poses environmental and economic challenges. To address this issue, this study designs a Mg-7.5Gd-6Zn-0.5Zr alloy (GZ76, wt.%) with low rare earth content, high strength, and excellent ductility. The morphology of the as-cast GZ76 alloy is characterized by a dendritic structure consisting of an α-Mg matrix and interdendritic zones comprising W+I phases, interspersed with fragmentary Zn-Zr phases. Furthermore, the extrusion process is employed to meticulously control the microstructure and enhance the mechanical properties of the alloy. This research focuses on investigating the effects of extrusion parameters on magnesium alloys to optimize their extrusion processing conditions. Through systematic manipulation of the extrusion ratio and extrusion speed, a comprehensive analysis is conducted to examine their impacts on grain refinement, texture evolution, distribution of second phase, and mechanical properties of extruded magnesium alloys. The results indicate that due to the insufficient recrystallization process, the microstructure of the as-extruded GZ76 alloys exhibits a bimodal structure, encompassing both fine recrystallized grains and coarse unrecrystallized grains. At larger extrusion ratio, a faster extrusion speed leads to superior mechanical properties of the alloy. Conversely, at smaller extrusion ratio, a slower extrusion speed is more favorable for achieving higher strength. These findings provide valuable insights into optimizing the extrusion parameters for enhancing the performance of magnesium alloys in engineering applications.

HTXRD based lattice thermal expansion and specific heat capacity modelling of C15-Fe2Zr Laves phase

Crystallographic phase pure C15-Fe2Zr was obtained through arc melting technique. X-ray Diffraction (XRD), scanning electron microscope (FESEM) along with energy-dispersive X-ray analysis (EDS) and differential scanning calorimetry (DSC)were employed to study the single phase in Fe-33.3at.% Zr alloy. Rietveld refinement of the high-temperature XRD patterns (from 298K-873 K) revealed the average linear and volumetric coefficients of thermal expansion of the alloys as αai= 0.3643 × 10−5 K−1 and αVi = 1.0916 × 10−5 K−1, respectively. The experimental heat capacity and enthalpy increment of the C15-Fe2Zr phase from 310K to 890K was modelled employing Quasi-harmonic Debye Grüneisen theoretical modelling by identifying the vibrational, electronic, anharmonic and magnetic contributions. Curie temperature(~625K) was determined from the magnetic contribution of the heat capacity.

Influence of re-melting rate on the dry sliding wear characteristics of LPBFed Cu–Cr–Zr alloy

For the past few decades, Copper alloys have made significant contributions to a variety of industrial applications due to their efficient electrical and thermal conductivity. However, moving mechanical assemblies continues to raise concerns about wear-related mechanical breakdowns on a worldwide scale. Hence, this research focuses on examining the wear parameters such as load, sliding velocity and distance based on the re-melting strategy of the (Laser Powder Bed Fusion) LPBF process. The sliding tests were carried out over a wide range load (15, 25, 35 and 45 N), sliding velocity (1, 1.5, 2 and 2.5 m/s) and sliding distance (1500, 2500, 3500 and 4500 m) with a pin-on-disc configuration. The LPBFed Cu–Cr–Zr alloy coupon was printed with four different re-melting ranges (5, 15, 30 and 45%) and it was explored to minimise the occurrence of un-melted particles and inter-particle gaps. The wear results show that the wear parameters have a positive correlation with the Wear Rate (WR) and co-efficient of friction (COF) and also witnessed that the WR and COF decrease with increasing the re-melting rate. The nano-hardness analysis was compared on the un-melted and spattered particles and the re-melted surface. The results show that the spattered particles possess 35.8% more nano-hardness than the other surface on the Cu alloy coupon printed with a 45% re-melting range. The FE-SEM images of the worn-out surface reveal that un-melted and spattered particles have a major contribution in reducing the wear resistance of the printed Cu alloy coupons.

Mechanical and high-temperature steam oxidation properties of Cr coatings deposited via high-power impulse magnetron sputtering

Applying protective coatings to Zr alloy cladding surfaces is one of the better methods to design fuel tolerant materials. In this study, the surface of a Zr-4 alloy was coated with Cr using high-power impulse magnetron sputtering. Furthermore, the mechanisms by which bias voltages affect the mechanical characteristics, resistance to high-temperature steam oxidation, and coating structure were elucidated. The coating exhibits a strong (200) weave structure with coarse grains at a bias voltage of -100 V. With increasing bias, the energy of deposited particles increases, grains continue to grow, (200) preferential growth orientation disappears, and the coating exhibits a (110) crystal orientation. The growth structure of the coating first shows a tendency to be dense and then loose. For the Cr coating with a (200) crystal orientation, a dense oxide layer is preferentially formed after oxidation, which can effectively block the internal diffusion of O. With increasing oxidation time, coarse Cr grains can effectively block the external diffusion of Zr. Furthermore, the Cr coating exhibiting a (110) crystal orientation was severely oxidized after oxidation, resulting in the formation of cracks at the film base; this accelerated the outward diffusion of Zr.

Role of Mo and Zr Additions in Enhancing the Behavior of New Ti–Mo Alloys for Implant Materials

AbstractThe utilization of Ti–Mo alloys in biomedical applications has gained attention for use in biomedical applications owing to their non-toxicity, reasonable cost, and favorable properties. In the present study, Ti–12Mo–6Zr and Ti–15Mo–6Zr alloys were prepared using elemental blend and mechanical alloying techniques. The effect of alloying elements Mo and Zr of Ti–Mo alloy, as well as the effect of fabrication techniques of Ti–Mo–Zr trinary alloys, were investigated. Thermodynamic calculations supported by CALPHAD analysis revealed that the addition of Zr increases lattice distortion, which contributes to enhancing the strength. Conversely, adding Mo decreases the enthalpy, facilitating improved mixing and solid solution formation. The as-sintered samples were characterized by X-ray diffraction, optical microscope, and scanning electron microscopy, and their microhardness, compressive, and corrosion behavior were investigated. Among all the investigated alloys, Ti–15Mo–6Zr alloy prepared by the mechanical alloying technique, milled for six hours at 300 rpm, compacted at 600 MPa, and sintered at 1250 ℃, shows good comprehensive mechanical properties with a preferable compressive strength (− 1710 MPa) and hardness (396 HV5), as well as the lowest wear rate (0.69%) and corrosion rate (0.557 × 10–3 mm/year). This can be related to the solid solution strengthening and relative density, together with dispersion and precipitation strengthening of the α phase. Remarkably, the combination of high mechanical and corrosion properties can be achieved by tailoring the content of the α phase, controlling the density, and providing new fabricating techniques for β Ti alloys. Graphical Abstract

Effect of Loading Direction on Tensile-Compressive Mechanical Behaviors of Mg-5Zn-2Gd-0.2Zr Alloy with Heterogeneous Grains

The tension-compression yield asymmetry caused by the strengthening of Mg-Zn-Gd-Zr alloy due to extrusion deformation is an important issue that must be addressed in its application. In this study, the effects of loading direction on the tensile and compressive mechanical behaviors of Mg-5Zn-2Gd-0.2Zr alloy were systematically investigated. As the loading angle (the angle between the loading direction and the extrusion direction) increases from 0° to 30°, 45°, 60° and 90°, the tensile yield strength decreases more significantly than the compressive yield strength. Consequently, the tension-compression yield asymmetry is gradually improved. Additionally, the ultimate compressive strength decreases more markedly than the ultimate tensile strength with the increment of the loading angle. In tensile tests conducted at 0°, 30° and 45°, two distinct stages of decreasing strain hardening rates are typically observed. For the 60° and 90° tensile tests, one unusual ascending stage of strain hardening rate is observed. For all compressive tests, three stages of strain hardening are consistently noted; however, the increment in strain hardening rate caused by {10–12} extension twinning decreases with the increasing loading angle. A model combining loading angle and Schmid factor distribution was established. The calculated results indicate that the dominant deformation modes during the yielding process also vary significantly with the loading conditions. This clarification highlights the differences in yield strength variations between tension and compression. Finally, an analysis of the plane trace and crack propagation direction near the fracture surface reveals the fracture mechanisms associated with tensile and compressive tests at different loading directions. This study promotes understanding of the mechanical behaviors of Mg-5Zn-2Gd-0.2Zr alloy under different loading directions, and helps to thoroughly elucidate the anisotropic effects of texture on the mechanical properties of magnesium alloys.

Microstructure and hot deformation behavior of Cu–Ti–Zr(-Mg) alloys

In this study, the thermal deformation behavior of Cu–Ti–Zr(-Mg) alloys were investigated by Gleeble-1500D. The two alloys were deformed at 700–900 °C with 0.003–10 s−1 strain rate. The intrinsic equations of the two alloys were constructed and calculated thermal activation energies, which indicates that it is improved from 325.67 kJ/mol to 344.03 kJ/mol after Mg addition. The result showed that the hot working area of Cu–Ti–Zr alloy is greatly extended after Mg addition, and rheological instability area is reduced. The morphology of the alloys was observed to analyze thermal behavior. It revealed that Mg elements inhibited the occurrence of dynamic recrystallization and shifted the texture types in the alloys by characterization of EBSD. TEM results showed that the phases during hot deformation in Cu–Ti–Zr–Mg are Cu4Ti and Cu10Zr7, which are in a semi-coherent relationship with the Cu matrix.

Improving the Mechanical Properties and Intergranular Corrosion Resistance of Al-9.2Mg-0.8Mn-0.2Zr Alloy by Sn Addition

Improving the Mechanical Properties and Intergranular Corrosion Resistance of Al-9.2Mg-0.8Mn-0.2Zr Alloy by Sn Addition

Construction of Dynamic Recrystallization Critical Strain Model, Kinetic Model, and Hot Workability of Mg–8Gd–4Sm–1Zn–0.5Zr Alloy

Construction of Dynamic Recrystallization Critical Strain Model, Kinetic Model, and Hot Workability of Mg–8Gd–4Sm–1Zn–0.5Zr Alloy

Bimodal grain structure, phase transformation, and mechanical properties of a Mg-Gd-Y-Zn-Zr alloy during hot extrusion

In this study, we investigated the evolution of grain structures and second phases of a Mg-9.5Gd-4Y–2Zn-0.3Zr alloy during two-stage deformation that took place in the metal during hot extrusion, as well as their effects on its mechanical properties. We found that the alloy exhibited a bimodal grain structure consisting of equiaxed dynamic recrystallized (DRXed) grains and elongated unDRXed grains. As the extrusion process progressed, DRX occurred on a large scale, resulting in an increase in the proportion of DRXed grains from 17.8% to 93.2%, and a reduction in average grain size from 80.3 μm to 9.41 μm. The grain orientation also underwent a transition from a single orientation of an extrusion direction (ED) parallel to <0001> (i.e. ED//<0001>) to mixed orientations of ED//<01–10> and ED//<0001>. The primary mechanism of dynamic recrystallization (DRX) during extrusion involved particle-stimulated nucleation (PSN) accompanied by both continuous and discontinuous DRX. The Mg-9.5Gd-4Y–2Zn-0.3Zr alloy mainly contained intergranular 18R-long period stacking order (LPSO) phases and intragranular 14H-LPSO. As the extrusion process progressed, 18R-LPSO changed from blocky to lamellar to accommodate deformation, and β-Mg5(Gd,Y) phase particles dynamically precipitated along DRXed grain boundaries. The 14H-LPSO phase was found to be primarily distributed within coarse unDRXed grains. As deformation via extrusion progressed, the quantity of 14H-LPSO gradually decreased. Ultimately, with the gradual dissolution of Mg5(Gd,Y), 14H-LPSO reprecipitated within the recrystallized grain boundaries. As the extrusion process progressed, both the yield strength (YS) and elongation (EL) increased from 132.6 MPa to 287.6 MPa and from 10.8% to 15.5%, respectively. This was mainly attributed to the significant reduction in grain size and second phase size.

Microstructure and Properties of Cu – Cr – Zr Alloys After Plastic Deformation and Aging

Microstructure and Properties of Cu – Cr – Zr Alloys After Plastic Deformation and Aging

Empowering Tri-Functional Palladium's Catalytic Activity and Durability in Electrocatalytic Formic Acid Oxidation Reaction via Innovative Self-Caging and Alloying Strategies.

Direct formic acid fuel cells (DFAFCs) stand out for portable electronic devices owing to their ease of handling, abundant fuel availability, and high theoretical open circuit potential. However, the practical application of DFAFCs is hindered by the unsatisfactory performance of electrocatalysts for the sluggish anodic formic acid oxidation reaction (FAOR). Palladium (Pd) based nanomaterials have shown promise for FAOR due to their highly selective reaction mechanism, but maintaining high electrocatalytic durability remains challenging. In this study, a novel Pd-based electrocatalyst (UiO-Pd-E) is reported with exceptional durability and activity for FAOR, which can be attributed to the Pd nanoparticles encapsulated within a carbon framework where concurrent chemical alloying of Pd and Zr occurs. Further, the UiO-Pd-E demonstrates noteworthy multifunctionality in various electrochemical reactions including electrocatalytic ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR) in addition to the FAOR, highlighting its practical potentials.

Effects of coolant pH on crud deposition behavior on fuel cladding tube under subcooled nucleate boiling condition in high temperature pressurized water

The effects of coolant pH on the crud deposition behavior on the Zr alloy and the FeCrAl fuel cladding tubes under subcooled nucleate boiling condition were investigated. With the increase of coolant pH, the coverage rate and thickness of crud on the surfaces of both the Zr alloy and the FeCrAl fuel cladding tubes showed a decreasing trend. The solubility of crud compositions was reduced due to the increase of coolant pH, which resulted in the inhibition of the crud deposition process caused by SNB condition. Consequently, the elevated coolant pH value reduced the amount of crud on the surface of the fuel cladding tube.

Refined Microstructure and Enhanced Anticorrosion Properties of Mg–4Y–3Nd–0.5Zr Alloy Fabricated by Laser Surface Remelting

Refined Microstructure and Enhanced Anticorrosion Properties of Mg–4Y–3Nd–0.5Zr Alloy Fabricated by Laser Surface Remelting

Formation of Structural-Phase State and Elastic and Durometric Properties of Biocompatible Cold-Rolled Titanium Ti–Nb–Zr-Based Alloys during Aging

The methods of scanning electron microscopy, X-ray diffraction analysis, and microindentation are used to study the effect of alloying with zirconium (within 3 to 6 at %) and complex Zr + Sn and Zr + Sn + Ta additions on the evolution of the structure, phase composition, and properties (effective modulus of elasticity, hardness, and wear-resistance parameters) of quenched biocompatible β-titanium (at %) Ti–6% Nb–% Zr, Ti–6% Nb–% Zr, Ti–6% Nb–% Zr, Ti–6% Nb–% Zr–% Sn, and Ti–6% Nb–% Zr–% Sn–0.7Ta alloys during aging (at 400°C for 4, 16, and 64 h) after multipass cold rolling with a total degree of strain of 85%. As compared to the quenching, the cold rolling of the studied Ti–b–r alloys is shown to suppress the occurrence of the β → ω transformation in the course of aging and to favor the acceleration of the decomposition of β solid solution with the formation of nonequilibrium αl phase in the course of aging. The increase in the zirconium content from 3 to 6 at % in the cold-rolled ternary Ti–6% Nb –х% Zr alloys and introduction of complex Zr + Sn and Zr + Sn + Ta additions to the Ti–6% Nb alloy instead of only zirconium addition hinder the decomposition processes of the β phase during aging; this impacts the intensity of variations of the effective modulus of elasticity and microhardness. The aging of the cold-rolled alloys under study was found to allows us to obtain the higher values of the parameters H/Er and (Н is the hardness and Er is the resolved modulus of elasticity) associated with the wear resistance as compared to those for the widely used medical Ti–Al–V alloy. The compositions of the alloys and conditions of their treatment are determined, which allow us to obtain the combination of the highest-level properties.

Hot deformation behavior and microstructural evolutions of a Mg-Gd-Y-Zn-Zr alloy prepared by hot extrusion

The hot deformation behavior of extruded Mg-9.5Gd-4Y-2Zn-0.5Zr alloy was studied through hot compression tests conducted at deformation temperatures of 350–500 °C and strain rates of 0.001–1 s−1. Under most deformation conditions, the flow stress first reached a maximum before decreasing to a stable value, demonstrating characteristics of dynamic recrystallization (DRX). The constitutive equation of the alloy was established as ε.=1.03*1011sinh0.01287*σp2.422exp(−171150/RT) through calculations and derivation. The influences of the deformation temperature and strain rate on the microstructure and DRX of the alloy during the hot compression process were investigated using electron backscatter diffraction. It was found that at temperatures between 350 °C and 450 °C, the alloy texture exhibited multiple {0001} peak rings distributed around the normal axis of the compression direction. When the strain rate was 0.001 s−1, the average equivalent grain diameter significantly increased from 3.3 μm to 22.4 μm with the rise in deformation temperature, whereas when the deformation temperature was 450 °C, the volume fraction of DRX grains noticeably decreased from 87.6 % to 13.2 % with the increasing strain rate. Further research revealed that due to the restriction of strain rate on grain boundary migration, discontinuous dynamic recrystallization and continuous dynamic recrystallization were the predominant DRX mechanisms at low and high strain rates, respectively.

Recrystallization of amorphous AlNbCr coatings irradiated with chromium ions

Applying an AlNbCr layer on the surface of Zr alloys significantly enhances the alloy resistance to oxidation and high-temperature corrosion. However, the effects of irradiation on AlNbCr coating remain largely unexplored. This work investigates the microstructural evolution of Cr ion-irradiated AlNbCr coatings under varying temperatures, utilizing bright-field transmission electron microscopy (TEM) observations and electron diffraction pattern analyses. With increasing Cr ion irradiation dose, the coatings gradually transitioned from an initial amorphous to a crystalline state. The onset of crystallization occurred earlier at higher temperatures, indicating that the crystallization process was significantly influenced by temperature. Moreover, the dynamic crystallization process of the crystalline structure was also analyzed, as well as the different irradiation responses at the Near-Interface Area (NIA) and Far-Interface Area (FIA). These findings provide new insights for understanding and optimizing the performance of AlNbCr coatings in high-irradiation environments.

Influence of direct aging treatment on microstructure and mechanical properties of Al-4Cu-2Mg-0.3Sc-0.7Zr alloy processed by selective laser melting

This work investigates the microstructure and mechanical properties of select laser melting (SLM) fabricated Al-4Cu-2Mg-0.3Sc-0.7Zr alloys after direct aging treatment. In the as-fabricated alloy, typical duplex grain microstructure, primary Al3(Sc, Zr) precipitates and CuMg co-segregation are observed. After aging treatment at 203 °C for 2.5 h, it was found that two types of S (Al2CuMg) precipitates with {100}Al and {120}Al growth direction. The superlattice lattice confirmed the presence of the secondary Al3(Sc, Zr) precipitates with L12 structure after aging at 225 °C to 496 °C. The disappearance of CuMg segregation and the coarser scale Al3(Sc, Zr) particles lead to the poor Zener-pinning effect and abnormal growth of fine grains at 496 °C aged. The fine secondary Al3(Sc, Zr) precipitates enhanced mechanical properties greatly, the yield strength achieved 435.5 MPa (increased about 18 %) with the elongation of 10.5 % after aging at 440 °C.