Zn Alloy Research Articles

Effect of Sn and Zn alloying with Al on its electrochemical performance in an alkaline media containing CO2 for Al-air batteries application

Aluminum alloyed with other metals, such as Sn and Zn, was synthesized via fusion to trace the impact of alloying elements on the electrochemical characteristics of Al anodes. The corrosion inhibition and electrochemical tests were performed in a 5 M KOH medium in the absence and presence of CO2 for the Al–Sn, and Al–Zn anodes and compared to the commercial aluminum. Tafel polarization exhibited that the anodic and cathodic branches display lower current densities than Al metal in pure KOH. The steady state of the open circuit voltage (Ecorr.) for the studied alloys was shifted to a more negative magnitude than for Al. The corrosion current is sharply decreased, and potential is significantly shifted to less negative values in the presence of CO2. This is due to forming of a protective layer from the carbonate of Al, Sn, and Zn on the surface. Amazing results were obtained and discussed in the case of CO2. Electrochemical impedance spectroscopy (EIS) results exhibited that charge transfer resistance (Rct) values rise with alloying elements. The data of Tafel plots are consistent with those of EIS. The alloying of Al with Sn and Zn elements significantly affects capacitance, hydrogen evolution process suppression, and charge-discharge efficiency. This reveals that the highest potential value in the presence of CO2 in the charging process is obtained for Al–Zn alloy, while the most negative potential is obtained for Al in the discharging process with CO2. Moreover, the discharge time is higher in the alloys than in commercial Al in the absence and more in the presence of CO2. The produced alloys are thought to provide good anodes for long-life rechargeable batteries.

Development, Processing and Aging of Novel Zn-Ag-Cu Based Biodegradable Alloys.

The use of biodegradable materials for implants is a promising strategy to overcome known long-term clinical complications related to permanent implants. Ideally, biodegradable implants support the damaged tissue for a certain period and then degrade, while the physiological function of the surrounding tissue is restored. Although Mg-based alloys nearly ideally lend themselves to biodegradable implants, a few critical shortcomings promoted the development of alternative alloy systems. Due to their reasonably good biocompatibility, moderate corrosion rate without hydrogen evolution and adequate mechanical properties, increasing attention has been paid to Zn alloys. In this work, precipitation-hardening alloys in the system Zn-Ag-Cu were developed relying on thermodynamic calculations. After casting the alloys, their microstructures were refined by thermomechanical treatment. The processing was tracked and directed, respectively, by routine investigations of the microstructure, associated with hardness assessments. Although microstructure refinement increased the hardness, the material proved to be susceptible to aging as the homologous temperature of zinc is at 0.43 Tm. Besides mechanical performance and corrosion rate, long-term mechanical stability is another crucial factor that must be taken into consideration to ensure the safety of the implant and thus requires a profound understanding of the aging process.

Understanding the superior mechanical properties of Mg–3Al–Zn alloy sheets: Role of multi-type unique textures

Understanding the superior mechanical properties of Mg–3Al–Zn alloy sheets: Role of multi-type unique textures

Linking the discharge behavior and microstructure of ternary Mg–Ca–Zn alloy anodes for magnesium-air cells

Three Mg–1Ca–1Zn (wt.%) alloy anodes with distinct microstructure characteristics (As-cast, water-cooled (WC) and furnace-cooled (FC)) are prepared by casting and homogenization treatment followed by different cooling methods. The relationship between microstructure and discharge behavior is systematically investigated. Due to the severe self-corrosion and discharge products adhesion caused by the formation of a large number of micro-galvanic couples, the As-cast anode shows the worst discharge performance. After homogenization treatment, the FC anode possesses an increased peak anodic efficiency of 56.6% and discharge capacity of 1250.11 mAh g−1 at 10 mA cm−2, however, the “chunk effect" induced by the linkage of discharge channels at the triple line boundary restricts cell efficiency. The WC anode exhibits the highest cell voltage at all discharge current densities, which is attributed to the high electrochemical activity and easily exfoliated discharge product layers. A novel discharge mechanism of the linear dissolution of α-Mg across grain boundaries results in uniform dissolution of the anode matrix, mitigative hydrogen evolution and smooth discharge pits. The WC anode exhibits the highest anodic efficiency of 62.9% and specific capacity of 1388.9 mA h g−1 at 10 mA cm−2, making it a promising anode material for Mg-air cells.

Structural Properties of Zn-Fe Alloy Coatings and Their Corrosion Resistance

Single-layer and multilayer alloy deposits were coated onto a mild steel substrate by a single-bath electroplating process. The developed coating consists of Zn and Fe alloys having different compositions with different layers. The anticorrosion behavior of single-layer and multilayer deposits was evaluated by the potentiodynamic polarization method. The surface morphology of the deposits was studied with a scanning electron microscope. The crystal structure of the deposits was analyzed with the X-ray diffraction technique. The Fe content in the deposit was analyzed by a colorimeter and verified with energy-dispersive X-ray spectroscopy. The micro-hardness tester with a Vickers indenter was used to evaluate the microhardness of the developed single-layer and multilayer coatings. It was found that the microhardness increased with applied current densities. The Zn-Fe multilayer coatings with 300 layers deposited with square and triangular pulses at the applied current density of 2.0/3.0 A dm−2 were five and four times more corrosion-resistant, respectively, than the single-layer coating of the same thickness. The development of Zn-Fe coatings that are resistant to corrosion is particularly important for the automotive industry and steel-based vehicle parts.

Effects of multi-pass friction stir processing on mechanical and tribological properties of Mg–Zn–Zr alloys

Owing to high strength and good biocompatibility, Mg–Zn binary alloys have attracted significant attention as a potential candidate for producing human implants. However due to the formation casting defects and dendritic structure, these alloys show poor mechanical and wear performances. Alloying and applying severe plastic deformation methods are suggested as two techniques for modifying and improving the above properties. In this study, dry-sliding wear and friction behaviors of the Mg–0.5Zn (MZ) alloy were enhanced by micro-alloying with Zr (0.25 wt%) and applying multi-pass friction stir processing (FSP) technique. Adding Zr reduced the average grain size (AGS) from 1.5 ± 0.3 mm in the MZ sample to about 510 ± 50 μm through the formation of evenly distributed Zr-rich particles with the chemical composition of Mg: 8.84, Zn: 0.75, and Zr: 90.41 A% in the structure. Furthermore, the attendance of thermostable Zr particles stimulated the dynamic recrystallization (DRX) during FSP and reduced the AGS to less than ≈2 μm after the 3rd FSP pass. This substantial grain refinement along with the casting defects reduction, and the fragmentation and redistribution of Zr particles enhanced the hardness and tensile properties of the substrate. Thus, the improved substrate in the FSPed samples, increased the stability of the formed tribolayer on the worn surfaces and changed the wear mechanisms from severe adhesive/delamination in the MZ alloy to mild abrasive/adhesive in the FSPed Zr-modified samples. Therefore, in the optimal condition (3-pass FSPed Mg–0.5Zn–0.25Zr sample), the hardness and total elongation percentage (EL%) increased by 55% and 648% while the mass loss and average friction coefficient (AFC) were reduced by 54% and 39%, respectively, compared to the as-cast Mg–0.5Zn alloy (under a load of 30 N).

The effect of permanent magnet stirring on the corrosion resistance of Sn-2.0Ag-0.5Cu-2Zn solder alloys in NaCl solution

Permanent magnet stirring (PMS) is adjusted to increase the alloy corrosion resistance by modifying the crystallographic texture. According to the findings, the lamellar structure had been converted into equiaxed grains by the PMS processing. Following exposure to a 3.5 wt percent NaCl solution, the corrosion behavior of the Sn-2.0Ag-0.5Cu-2Zn alloy was examined using electrochemical methods (polarization and electrochemical impedance spectroscopy (EIS)) and surface analysis using SEM, EDX and XRD. According to the PDP curves, the PMS treatment procedure significantly reduces the values of corrosion current density (icorr) and shifts the corrosion potential (Ecorr) to more positive noble values. The Ecorr values of SAC (205)-2Zn and SAC (205)-2Zn with PMS are increased from −936.66 to −756.18 mV (vs. SCE). Also, the pitting resistance is higher in case of PMS treated alloy as indicated from cyclic polarization (CP). PMS treated alloy possess higher Erep values than Ecorr values, confirming the ability of passive film to restore itself. EIS data showed that the diameter of capacitive loop for PMS-treated SAC (205)-2Zn alloy is approximately four times as the untreated alloy indicating less corrosion rate and higher protection.

Laser powder bed fusion of a novel high strength Al-Mg alloy via Si and Zn microalloying

Doping expensive elements, such as Sc or Zr, is an effective method for development of laser additively manufactured high strength Al-Mg alloys. In this work, a novel high strength Al-Mg alloy was fabricated by laser powder bed fusion (LPBF) via microalloying of cost-effective Si an Zn elements. The microstructures were typically featured by nanosized cellular eutectic Mg2Si and solute supersaturation of Zn. The as-LPBFed Al-5Mg-2Si-1.4Zn alloys exhibited high ultimate tensile strength of 506 MPa, yield strength of 382 MPa and elongation of 7.3%. This study provides a new strategy for the fabrication of high strength Al-Mg alloys by LPBF.

Strengthening Mechanism of Rotary-Forged Deformable Biodegradable Zn-0.45Li Alloys.

The use of zinc (Zn) alloys as a biodegradable metal for medical purposes has been a popular research topic. This study investigated the strengthening mechanism of Zn alloys to enhance their mechanical properties. Three Zn-0.45Li (wt.%) alloys with different deformation amounts were prepared by rotary forging deformation. Their mechanical properties and microstructures were tested. A simultaneous increase in strength and ductility was observed in the Zn-0.45Li alloys. Grain refinement occurred when the rotary forging deformation reached 75.7%. The surface average grain size reached 1.19 ± 0.31 μm, and the grain size was uniformly distributed. Meanwhile, the maximum elongation of the deformed Zn-0.45Li was 139.2 ± 18.6%, and the ultimate tensile strength reached 426.1 ± 4.7 MPa. In situ tensile tests showed that the reinforced alloys still broke from the grain boundary. Continuous and discontinuous dynamic recrystallization during severe plastic deformation produced many recrystallized grains. During deformation, the dislocation density of the alloy first increased and then decreased, and the texture strength of the (0001) direction increased with deformation. Analysis of the mechanism of alloy strengthening showed that the strength and plasticity enhancement of Zn-Li alloys after macro deformation was a combination of dislocation strengthening, weave strengthening, and grain refinement rather than only fine-grain strengthening as observed in conventional macro-deformed Zn alloys.

Effects of Sn and Mn Addition on the Microstructure and Mechanical Properties of As-Extruded Mg–2Al–1Zn Alloys

Effects of Sn and Mn Addition on the Microstructure and Mechanical Properties of As-Extruded Mg–2Al–1Zn Alloys

Effects of homogenization on the microstructural evolution of a novel Zr and Er containing Al–Mg–Zn alloy

In this study, the microstructural evolution of Al–Mg–Zn–Er–Zr alloys during the homogenization process is investigated. The primary phase dissolution and solute diffusion were studied based on microstructural characterization and kinetic analysis. The results showed that the primary phase completely dissolved and the solute elements are uniformly diffuse for homogenization at 460 °C/24 h. The Al3 (Er, Zr) second phase precipitates during the homogenization of Al–Mg–Zn–Er–Zr alloys. Compared with the traditional single-stage homogenization, the two-stage homogenization promotes the uniform precipitation of the Al3(Er, Zr) phase, which improves the chain distribution of the Al3(Er, Zr) phase and increases hardness of the alloy. The optimal homogenization treatment is 320 °C/10 h + 460 °C/24 h, which is consistent with the results of the homogenization kinetic analysis.

Effect of thiosulfate on the passivation of zinc-alloys in 3.5 wt% NaCl solution at 353 K

Abstract The effect of thiosulfate (S2O3 2−) with the different concentrations (100 g m−3, 150 g m−3, 200 g m−3) on the passivation of Zn alloys in artificial seawater at 353 K is investigated by using immersion tests, electrochemical measurements, and field emission scanning electron microscopy (FE-SEM) with EDX. It is found that the presence of thiosulfate in the solution can hinder the passivation. Potentiodynamic polarization results show that thiosulfate increases the current density at which the thin passive films with the low corrosion resistance are formed. Thiosulfate effect to retard the passivation, is different with the concentrations exposed to the respective Zn alloys based on the Al content. Due to the presence of various Zn and Al protective compounds at the surface, the passivation of Zn alloys occurs at the immersion time of 432 ks in the form of thin film. After the immersion time is 1037 ks, the passivation is still approximately as close as 432 ks inhibiting the film growth by the effect of thiosulfate and depassivation also would be occurred with the removal of the oxide thin film by the longer immersion time.

Determination of critical resolved shear stresses associated with slips in pure Zn and Zn-Ag alloys via micro-pillar compression

The room-temperature plastic deformation behavior of pure Zn and Zn-Ag (0–2.2 at.%) biodegradable alloys has been investigated via uniaxial in situ micro-pillar compression tests performed within a scanning electron microscope. The critical resolved shear stresses (CRSS) were quantified as a function of micro-pillar diameter. The compression of single crystal micro-pillars was performed at various strain rates in carefully selected grains, the crystallographic orientation of which facilitates deformation either via basal 0001〈112¯0〉 or prismatic 101¯0〈112¯0〉 slip. The CRSS values increased with decreased micro-pillar diameter, revealing a more pronounced size effect in pure Zn deformed via basal slip. The observed solid solution strengthening effect in Zn-Ag alloys with increasing Ag content was associated with a CRSS increase from 26.6 MPa to 37.0 MPa (by ∼ 40 %) in the basal slip system and from 99.1 MPa to 188.4 MPa (by ∼ 104 %) in the prismatic slip system. The extraordinarily high CRSS values for basal slip activated in pure Zn and Zn-0.14Ag alloy compared to the solid solution strengthening model was attributed to the critically low dislocation density. In the Zn-Ag alloy with Ag content > 0.5 at.% higher dislocation densities are expected, which result in a more predictable plastic deformation behavior.

A bimodal grain structured Zn–0.5Ag–0.2Mg alloy with high strength and ductility achieved through combined ECAP and cold rolling

Zn–Ag alloys are particularly promising for application as biodegradable implant materials due to their harmless degradation products, suitable degradation rate, and remarkable biocompatibility. Nonetheless, their mechanical properties are generally below the requirements for medical implants. In this work, a bimodal grain structured Zn–0.5Ag–0.2Mg alloy with excellent strength and ductility was achieved through combined equal channel angular pressing (ECAP) and cold rolling (CR), significantly superior to their counterparts obtained through ECAP or CR. Specifically, the ultimate tensile strength (UTS) and elongation (EL) of the alloy are as high as 332 MPa and 63%, respectively, far exceeding the application requirements. In achieving the excellent mechanical properties, a key role is played by hetero-deformation induced (HDI) strengthening. This work may provide practical guidance for developing high-performance Zn alloys.

Synthesis and in vitro evaluation of Ca-P coating on biodegradable Zn alloys

• Ca-P coating was fabricated on Zn-Mg alloy. • Ca-P coating inhibits the explosive release of Zn 2+ of Zn-Mg alloy. • Ca-P coating exhibits superior antibacterial activity and biocompatibility. The burst release of Zn 2+ from the naked pure Zn and Zn-based alloys could induce local and systemic toxicity, which limits their clinical applications as biodegradable implants. In order to inhibit the explosive release of zinc ions, a protective Ca-P coating was synthesized on biodegradable Zn alloy. The microstructure, corrosion resistance, antibacterial activity, and biosafety of the Ca-P coating are systematically investigated. Electrochemical tests revealed that Ca-P protective layer has enhanced the anti-corrosion behavior of Zn alloy. Furthermore, Ca-P protective layer showed good biocompatibility, as demonstrated by significantly increased cell viability, good attachment, and spreading at a higher cell density. Besides, the Ca-P coating could also retain the antibacterial ability and inhibit the bacterial adhesion. The Ca-P protective layer synthesized on biodegradable Zn alloy can be considered and applied in future biomedical applications.

Acceptable Concentrations of Cu and Ni in Corrosion Resistance of Mg–6 mass% Zn Alloy

Cu and Ni impurities in Mg alloys are deleterious contaminants that reduce the corrosion resistance of the alloy. Mg2Cu and Mg2Ni precipitates can cause significant anodic dissolution of the Mg matrix, owing to their potential difference. Suppression of these phases can prevent the deterioration of corrosion resistance. The neutralization of these impurities through the formation of Mg–Zn intermetallic phases has been studied, because the atomic radii of Cu and Ni are similar to that of Zn. As a result, the MgZn2 phase may precipitate during the rapid cooling that occurs during the solidification of the Mg–6 mass% Zn alloy, and introduce substitutional impurity atoms in the crystal lattice. Mg(Zn, Cu)2 and Mg(Zn, Ni)2 phases can be formed instead of Mg2Cu and Mg2Ni, in the presence of both of Zn and these impurities. The microstructures and corrosion properties of the Mg–6 mass% Zn alloy with various Cu or Ni concentrations are investigated in this work. The Cu and Ni impurities are concentrated into MgZn2 phase in the Mg–6 mass% Zn alloy without Mg2Cu or Mg2Ni formation when the concentrations of these impurities are within acceptable limits. Consequently, the corrosion rate of the Mg–6 mass% Zn alloy with 1.4 mass% Cu or 0.25 mass% Ni is almost the same as that of the alloy without Cu and/or Ni contaminations.

Microstructure Evolution and Local Hardness of Mg–Y–Zn Alloys Processed by ECAE

Mg–9 at%Y–6 at%Zn and Mg–2 at%Y–1 at%Zn alloys were processed by equal-channel-angular extrusion (ECAE) to investigate their microstructure evolution and local hardness. The area fraction of the kink bands in the Mg–9 at%Y–6 at%Zn alloys increased with increasing the number of ECAE passes, resulting in higher hardness. In contrast, the number of kink boundaries in the local region near the indentation was almost constant. The relationship between the microstructure factors of the kink bands and the local hardness is discussed in comparison with the forged alloy. In the Mg–2 at%Y–1 at%Zn alloys, the microstructural evolution of the α-Mg matrix phase and long-period stacking ordered (LPSO) phase by 1-pass ECAE and the increase in local hardness were discussed.

Biodegradable Zn-0.5Li alloy rib plate: Processing procedure development and in vitro performance evaluation

• Whole fabricating process of biodegradable Zn-Li alloy rib plates is developed. • Zn-0.5Li alloy rib plates have mechanical properties comparable to pure Ti. • Uniform corrosion dominates during immersion tests in SBF up to 30 days. • The Zn alloy rib plates have better biocompatibility than pure Zn rib plates. Trauma kills more than four million people worldwide each year, with chest trauma accounting for 25% of these deaths. Rib fractures are the main manifestation of chest trauma. Biodegradable Zn alloys offer a new option to overcome clinical problems caused by permanent rib fracture internal fixation materials, e.g., long-term stress masking and secondary surgery. In this study, the fabrication procedure of biodegradable Zn-0.5Li alloy rib plates is successfully developed, which consists of casting, hot-warm rolling, cutting, and pressing sequentially. Biomechanical three-point bending performance of the Zn alloy rib plates is comparable to that of commercial pure Ti rib plates, much higher than that of pure Zn rib plates. In addition, the Zn alloy exhibits the best antibacterial ability against E. coli and S. aureus among the three materials. Although the Zn alloy exhibits a weaker MC3T3 cytocompatibility than pure Ti, it is better than pure Zn. This study provides a foundation for the future development of various biodegradable Zn alloy rib plates.

Relationship between Cluster-Arranged Nanoplate Formation and Mechanical Properties of Dilute Mg–Y–Zn Alloys Prepared by Combination of Low-Cooling-Rate Solidification and Extrusion Techniques

High-strength dilute Mg–Y–Zn alloys with cluster-arranged layer/nanoplate (CAL/CANaP) precipitates were developed via combined processes of low-cooling-rate solidification and extrusion techniques. The effects of CANaP morphology and deformation kink bands installation on the tensile properties of the extruded Mg–Y–Zn alloys were investigated. A slow-cooling solidification process with a cooling rate range of 0.1–0.01 K·s−1 produces a CAL-aggregated region in the α-Mg matrix. The CAL-aggregated region comprises long-period stacking ordered (LPSO) nanoplates with an intergrowth structure and the solo-CAL precipitates. The area fraction of the CAL-aggregated region increased with decreasing cooling rate. The microstructure of the extruded Mg99.2Y0.6Zn0.2 alloys prepared from low cooling rate-solidified ingots consisted of three characteristic regions: (i) dynamically recrystallized (DRXed) fine α-Mg grains, (ii) worked coarse α-Mg grains with a CAL-aggregated region, and (iii) worked blocky LPSO grains. The strength and ductility of the extruded Mg–Y–Zn alloys may be controlled by the volume fractions of the worked and DRXed grains, respectively. It is desirable to control the CANaP thickness and spacing to ∼1 µm and ∼0.8 µm or more, respectively, to promote DRX. Conversely, it is necessary to control the CANaP thickness and spacing to ∼1 µm and ∼0.8 µm or less, respectively, to form the worked grains in which kink bands are introduced.

Study on Machinability of Lead-Free α + β Brass 62.5Cu–1Si–Zn Alloy

Free-cutting brass contains 3% lead to obtain excellent machinability, but because lead is harmful to the human body, lead regulations are being tightened in Europe, starting with the 2010 and 2014 lead control laws for drinking water-related equipment in the United States, and including RoHS regulations, ELV regulations, and the 4MS Positive List. Being affected by these increasingly strict lead regulations in Europe and the United States, demand for brass with significantly reduced lead content is on the rise.