Pct Zn Research Articles

Microstructure and Mechanical Properties of Low Stacking-Fault Energy Cu-Based Alloy Wires

Innovations in electronic devices and their capabilities have driven the demand for improved conductive materials relevant to device fabrication. To gain insights on developing solid solution-type Cu alloy thin wires with a superior balance of strength and conductivity, this study investigated variations in the microstructures and properties of pure Cu wires and Cu–5 at. pct Zn, Cu–5 at. pct Al, and Cu–5 at. pct In alloy wires during intense drawing and analyzed the effects of stacking-fault energy (SFE) of Cu alloys on their microstructural evolution. During the initial drawing stages, lower SFE Cu–5 at. pct Al and Cu–5 at. pct In alloys yielded more high-density deformation twins than pure Cu and Cu–5 at. pct Zn. Deformation twins promoted grain refinement during drawing. Effective grain refinement and dislocation accumulation during drawing in low-SFE Cu alloys substantially strengthened them without adversely impacting electrical conductivity. During intense drawing in the Cu–5 at. pct In alloy wires, ultrafine fibrous grains (diameter ~ 80 nm) and a high-dislocation density yielded excellent tensile strength and conductivity. These results indicate that adjusting the solute element content in Cu matrix to reduce SFE and optimizing deformation strain via wire drawing significantly improve alloy wire performance.

Cellular Automata Modeling of Two Discontinuous Reactions in Fe-13.5 At. Pct Zn Alloy During Ageing and Annealing

Cellular Automata Modeling of Two Discontinuous Reactions in Fe-13.5 At. Pct Zn Alloy During Ageing and Annealing

Enhancement of the Strength–Ductility Balance in Cu–40 Pct Zn Alloy by Single Roll Drive Rolling and Cooling-Assisted Friction Stir Processing

Enhancement of the Strength–Ductility Balance in Cu–40 Pct Zn Alloy by Single Roll Drive Rolling and Cooling-Assisted Friction Stir Processing

Experimental study and thermodynamic modeling of distribution of elements among slag, matte and metal in the Cu–Fe–O–S–Si–(Zn)–(Al, Ca, Mg) system for copper slag cleaning applications

The distributions of zinc and other elements in the Cu–Fe–S–Si–O–(Zn) system among slag, matte and metal phases were determined experimentally at 1200 °C (1473 K). The experimental procedure involved high-temperature equilibration, quenching of the samples and measurement of the phase compositions using the electron probe X-ray microanalysis. Conditions of experiments were planned using thermodynamic calculations and the experimental results were used to further develop thermodynamic models. Matte grades from 0 to 80 wt. pct Cu were investigated, concentrations of 3, 6 and 8 wt. pct Zn in slag were targeted. Additional set of experiments was undertaken to study the effects of Al2O3, CaO and MgO on the distribution of zinc and other elements. All samples were in equilibrium with tridymite (SiO2). Metal phase was either liquid copper or solid metallic iron. Conditions of equilibrium with metal phase are of practical importance for the development of smelting reduction technologies for the copper slag cleaning and recycling.

Effects of Zn on Microstructure Modification and Mechanical Properties Improvement of Al-Si-Cu-Mg Alloys

In this research, the influence of Zn on the microstructure and mechanical properties of Al-Si-Cu-Mg alloys under different solidification rates was investigated. Differential scanning calorimetry was used to detect the nucleation and growth of eutectic Si, while scanning electron microscopy was used to analyze Fe-rich phases. Two growth models were deduced to explain the modification of the eutectic Si and Fe-rich phases upon the addition of Zn. The results show that an addition of 0.6 wt pct Zn modified the eutectic Si from flake like and fibrous to micron- and submicron-granular structures, depending on the different secondary dendrite arm spacings of ~ 33 μm and ~ 16 μm, respectively. For the Fe-rich phases under steel mold casting conditions, β-Al5FeSi was modified into π-Al8FeMg3Si6 upon adding 0.6 wt pct Zn. Under sand mold casting conditions, the 0.6 wt pct Zn addition only refined the size of the β-Al5FeSi. The Zn addition significantly improved the ultimate tensile strength and elongation. The excellent modification effect of Zn on the eutectic Si and Fe-rich phases was attributed to the fact that the reaction of the Zn-Si eutectic on the {111}Si planes forced the Si atoms from these phases into the eutectic droplets.

Occurrence and Morphology of Martensite in \u03b2-Cu-Zn Alloys with Minor Al Additions

The limits of occurrence and the morphology of martensite in Cu-Zn-Al alloys with 30 to 50 wt pct Zn and ≤ 1.5 wt pct Al have been investigated. In samples with concentration gradients, various conditions for the competition between martensitic and massive transformation have been observed. Microstructural details of martensite were obtained by combining vibration polishing, chemical or plasma etching and polarized light, backscattered electron channeling contrast or electron backscatter diffraction analysis. Depending on the cooling rate, martensite undergoes a morphological change from self-accommodating thin plates to lenticular shaped plates, which is documented for the first time in Cu-based alloys. The number of martensite twins in the investigated compositional range was found to be significantly smaller than that in commercial Cu-Zn-Al alloys that are used as shape memory alloys.

Influence of Minor Cr-Additions to the Growth of Columnar Dendrites in Al-Zn Alloys: Influence of Icosahedral Short Range Order in the Liquid

The effect of minute Cr additions on dendritic growth directions in Al-20 wt pct Zn alloy has been investigated. As first evidenced by Gonzales and Rappaz (Metall Mater Trans A 37:2797–2806, 2006) Al-Zn alloys exhibit a Dendrite Orientation Transition (DOT), from 〈100〉 below 25 wt pct Zn to 〈110〉 above 60 wt pct, regardless of the solidification speed. The DOT has been interpreted as a modification of the solid–liquid interfacial energy anisotropy (Gonzales and Rappaz, 2006; Haxhimali et al. in Nat Mater 5:660–664, 2006). However, 0.02 to 0.1 wt pct addition of Cr in Al-20 wt pct Zn drastically modifies the dendrite trunk direction from 〈100〉 to 〈110〉 at low solidification speed, typically 200 μm/s. Even more surprising, 〈100〉 dendrite trunks are retrieved in Al-20 wt pct Zn-0.1 wt pct Cr when the speed is increased to 1000 μm/s, but with the concurrent formation of twinned dendrites. Minute additions of Cr have been reported recently to promote icosahedral short range order (ISRO) in liquid Al-Zn, thus reducing the atomic mobility (Kurtuldu et al. in Acta Mater 115:423–433, 2016) and modifying the nucleation kinetics (Kurtuldu et al. in Acta Mater 61:7098–7108, 2013). The present results indicate that ISRO also modifies the attachment kinetics of icosahedral clusters rather than individual atoms, and is most likely responsible of growth direction change in Al-Zn-Cr alloy and of twinned dendrites formation.

Effect of Main Elements (Zn, Mg, and Cu) on Hot Tearing Susceptibility During Direct-Chill Casting of 7xxx Aluminum Alloys

New 7xxx aluminum alloys with high alloying contents are being designed, which could induce serious hot tearing defects during direct-chill (DC) casting. Among all factors affecting hot tearing of 7xxx alloys, undoubtedly alloying elements play a significant role. In this study, the effect of main alloying elements (Zn, Mg, and Cu) on hot tearing of grain-refined Al-xZn-yMg-zCu alloys was investigated by a dedicated hot tearing rating apparatus simulating the DC-casting process. It was found that the minimum and maximum hot tearing susceptibilities occur for 4 to 6 and 9 wt pct Zn, respectively, indicating the complicated effect of Zn content. The hot tearing resistance of grain-refined Al-9Zn-yMg-zCu alloys is enhanced with increasing Mg content but is deteriorated with increasing Cu content. This can be attributed to the interaction of the thermal stresses, melt feeding, and final eutectics. The observed tendencies of the main alloying elements on hot tearing were also confirmed for four commercial 7xxx alloys. In addition, both the load value at non-equilibrium solidus and the SKK criterion proposed by Suyitno et al. using measured load developments were found to be good indicators in predicting hot tearing susceptibility. This study can provide a beneficial guide in designing 7xxx alloys considering the potential occurrence of hot cracks beforehand.

A Novel Approach to Structure Modification of Brasses by Combination of Non-equilibrium Heat Treatment and Friction Stir Processing

A non-equilibrium heat treatment was used to produce secondary phase (β) in the single phase brass (α), which caused the modification of the grain structure and mechanical properties after friction stir processing. For this aim, the single phase brass plate containing 37 wt pct Zn was heated at 810 °C for 1 hour, and then quenched in water, which caused the formation of non-equilibrium secondary β phase. After the non-equilibrium heat treatment, bead on plate friction stir processing was employed. The origin of the modification by β phase was studied using high resolution electron backscattered diffraction and transmission electron microscopy. The results showed that the average grain size, yield strength, and strain-hardening exponent were changed, respectively, from 4.8 µm, 166 MPa and 0.28 to 2.1 µm, 213 MPa and 0.25 in the presence of β phase. The β phase promoted the discontinuous dynamic recrystallization by particle-stimulated nucleation mechanism, and then transformed to α resulting in a finer microstructure with more random texture. In addition, the nanometer-sized β particles were retained at the grain boundaries, which reduced their mobility and hence the grain growth was inhibited.

In Vitro Biodegradation and Mechanical Properties of Mg-Zn Alloy and Mg-Zn-Hydroxyapatite Composite Produced by Mechanical Alloying for Potential Application in Bone Repair

A biodegradable Mg-6.5 wt pct Zn (Mg-Zn) alloy and Mg-6.5 wt pct Zn reinforced with 10 wt pct hydroxyapatite (HA) composite were prepared by mechanical milling. In vitro biodegradation activity as a function of immersion time was performed in Hank’s balanced salt solution (HBSS). The dissolution of Mg ions (Mg2+) decreased from 75.74 µg/ml of pure Mg to 59.24 µg/ml and 46.88 µg/ml corresponding to the Mg-Zn alloy and Mg-Zn/HA composite, respectively. This finding indicates the progressive effect of HA followed by the Zn addition in decelerating the degradation rate of Mg. More positive corrosion potential of Mg-6.5 wt pct Zn alloy (− 1.5015 V) and Mg-Zn/10 wt pct HA composite (− 1.4647 V) than that of pure Mg (− 1.6972 V) suggested that the Mg-Zn/10 wt pct HA composite exhibited the highest corrosion resistance in the bioenvironment. The compressive strength values after 7 days of immersion in HBSS of the Mg-Zn alloy and Mg-Zn/HA composite are 230.64 and 278.46 MPa, respectively, and these are considerably higher compared to the compressive strength of the cortical bone (100 to 230 MPa).

In Situ Observation of the Zr Poisoning Effect in Al Alloys Inoculated by Al-Ti-B

In situ synchrotron X-ray radiography observations of the Zr-poisoning phenomenon of an Al-20 wt pct Zn alloy inoculated by Al-5Ti-1B were carried out. The effects of Zr addition on heterogeneous nucleation, grain growth, and final grain size were quantitatively studied and further analyzed using the interdependence model. The experimental results show that the undercooling needed for nucleation increases and the nucleation rate decreases at the early stage of solidification with Zr addition, resulting in fast grain growth, a high solidification rate and increased severity of solute segregation in the solid–liquid coexistence regions. At the same time, the poisoning is a progressive process that is enhanced with the increasing Zr content, holding temperature, and holding time. The nucleation-free zone of the Zr-containing sample, either measured from the radiographs or calculated by the interdependency theory, is larger than that of the Zr-free sample. Our analysis shows that both the increase in the nucleation-free zone and the average interparticle spacing of the most potent available nucleation particles contribute to the increase of the grain size caused by Zr poisoning.

Enhanced Mechanical Properties and Corrosion Behavior of Biodegradable Mg-Zn/HA Composite

Magnesium (Mg) and its alloys have shown potential for use in the biomedical industry due to their excellent biological performance and biodegradability in the bioenvironment. Thus, the aim of the present study was to develop a reliable biodegradable hard tissue substituent. Biodegradable and bioactive Mg-Zinc (Zn) reinforced by hydroxyapatite (HA) composite was prepared using mechanically alloyed Mg-6.5 wt pct Zn and pure HA powders as starting materials. Various HA contents (i.e., 5, 10, 15, and 20 wt pct) were introduced in forming the Mg-Zn/HA composite. The effect of bioactive HA incorporation in biodegradable Mg-6.5 wt pct Zn alloy matrix on mechanical and biodegradation properties as well as microstructural observation was investigated. As measured by the Williamson–Hall formula, the Mg crystallite size of the sintered composites containing 5, 10, 15, and 20 wt pct HA were 36.76, 29.08, 27.93, and 27.31 nm, respectively. According to X-ray diffraction (XRD) analysis, there was no new crystalline phase formed during milling, indicating that no mechanochemical reactions between Mg-Zn alloy and HA occurred. The −1.70 V shifted significantly toward the passive position of the plain Mg-6.5 wt pct Zn alloy and Mg-Zn/10 wt pct HA composite, which were −1.50 and −1.46 V, respectively, indicating that the Mg-Zn/10 wt pct HA composite was least susceptible to corrosion in the bioenvironment.

Damping Capacities of Mg-4 Pct Zn-(0-0.5) Pct Ca Biomedical Alloys

This study is intended to investigate the damping capacities of cast Mg-4 pct Zn-(0-0.5) pct Ca biomedical alloys. The Mg-4 pct Zn-(0-0.5) pct Ca alloys had similar damping levels regardless of Ca content in the strain-amplitude-independent region, but showed a decreasing tendency with an increase in Ca content in the strain-amplitude-dependent region. Almost identical concentration of solutes in the α-(Mg) matrix and the increased number density of the precipitate particles are responsible for the damping behaviors in the strain-amplitude-independent and strain-amplitude-dependent regions, respectively.

Optimization Study on the Leaching of High Iron-Bearing Zinc Calcine After Reduction Roasting

The selective leaching of zinc from high iron-bearing zinc calcine after reduction roasting was optimized by Taguchi experimental design method. The experimental parameters and their ranges were 303 to 343 K (30 to 70 °C) for leaching temperature (T), 7 to 15 mL/g for liquid/solid ratio (L/S), 70 to 150 g/L for H2SO4 concentration (C), 5 to 25 minutes for time (t), and 100 to 500 rpm for stirring speed (R). The results show that the optimum conditions were 303 K (30 °C), 9 mL/g, 110 g/L, 20 minutes, and 400 rpm, respectively. Under these conditions, about 92.81 pct Zn was extracted and more than 86 pct Fe was reported into the leach residue. L/S and C had significant effects on the extractions of zinc and iron, while t and R had no significant effects, and T had significant effect on iron extraction but negligible effect on zinc extraction. This indicates that diffusion was not a major control step of the leaching process, and the dissolution of iron was controlled by chemical reaction. The interactive effects of parameters were negligible. The leach residue was mainly composed of Fe3O4 and ZnS, and its particle size was very fine.

Measurement of Mechanical Coherency Temperature and Solid Volume Fraction in Al-Zn Alloys Using In Situ X-ray Diffraction During Casting

During solidification of metallic alloys, coalescence leads to the formation of solid bridges between grains or grain clusters when both solid and liquid phases are percolated. As such, it represents a key transition with respect to the mechanical behavior of solidifying alloys and to the prediction of solidification cracking. Coalescence starts at the coherency point when the grains begin to touch each other, but are unable to sustain any tensile loads. It ends up at mechanical coherency when the solid phase is sufficiently coalesced to transmit macroscopic tensile strains and stresses. Temperature at mechanical coherency is a major input parameter in numerical modeling of solidification processes as it defines the point at which thermally induced deformations start to generate internal stresses in a casting. This temperature has been determined for Al-Zn alloys using in situ X-ray diffraction during casting in a dog-bone-shaped mold. This setup allows the sample to build up internal stress naturally as its contraction is prevented. The cooling on both extremities of the mold induces a hot spot at the middle of the sample which is irradiated by X-ray. Diffraction patterns were recorded every 0.5 seconds using a detector covering a 426 × 426 mm2 area. The change of diffraction angles allowed measuring the general decrease of the lattice parameter of the fcc aluminum phase. At high solid volume fraction, a succession of strain/stress build up and release is explained by the formation of hot tears. Mechanical coherency temperatures, 829 K to 866 K (556 °C to 593 °C), and solid volume fractions, ca. 98 pct, are shown to depend on solidification time for grain refined Al-6.2 wt pct Zn alloys.

Mechanical Property and Intergranular Corrosion Sensitivity of Zn-Free and Zn-Microalloyed Al-2.7Cu-1.7Li-0.3Mg Alloys

The influence of 0.72 pct Zn addition on the tensile properties of Al-2.7Cu-1.7Li-0.3Mg alloys was investigated. Their intergranular corrosion (IGC) dependence on aging [T6 type at 423 K (150 °C) and 448 K (175 °C) and T8 type at 423 K (150 °C)] time was studied. An IGC diagram associated with aging process was established. The addition of 0.72 pct Zn enhanced the strength of the Al-Li alloy with T6 type aging at 448 K (175 °C). With aging process, the corrosion mode of the T6-aged Al-Li alloys was changed in the following order: pitting and local IGC (initial aging stage), general IGC (underaging stage), local IGC (near peak-aging stage), and pitting (overaging stage) again. The IGC depth was increased first and then decreased with aging time extension. The corrosion potential change of grains and the microstructure variation were used to explain the IGC sensitivity of the Al-Li alloy with different tempers. Meanwhile, 0.72 pct Zn addition decreased the IGC sensitivity of the Al-Li alloy, especially the T6-aged Al-Li alloy.

Experimental and Diffusion Simulation for the Homogenization of As-cast Mg-Al, Mg-Zn, and Mg-Al-Zn Alloys

Annealing of as-cast Mg-Al alloys (3, 6, and 9 wt pct Al) and Mg-Zn alloys (1.5, 4.0, and 5.5 wt pct Zn) was performed at 603 K and 673 K (330 °C and 400 °C) for 1, 2, 4, and 8 hours to systematically investigate the variation of second phase fraction and solute concentration profile in Mg matrix using SEM image analysis and EMPA-WDS, respectively. To calculate second phase fraction and solute concentration profile, a diffusion model considering the moving boundary was constructed, and the experimental results were successfully explained by the model. The expansion of model to ternary Mg-Al-Zn alloy is also described. This model can be used for the optimization of homogenization process of the Mg alloys.

Effects of Alloying Elements on Creep Properties of Mg-Gd-Zr Alloys

The minimum creep rate and microstructures of aged samples of Mg-Gd-Zr alloys, with and without alloying additions of Zn and/or Y, have been investigated in the present work. The creep tests were performed at 523 K (250 °C) and under 80 to 120 MPa, and the microstructures before and after creep tests were characterized using scanning electron microscopy, transmission electron microscopy, and the high-angle annular dark-field imaging technique. It is found that dislocation creep predominates in the steady-state creep stage for all alloys. The Mg-2.5Gd-0.1Zr (at. pct) alloy, strengthened by the β′ precipitates, has minimum creep rates in the range 1.0 × 10−8 to 3.8 × 10−8 s−1 under 80 to 120 MPa. The addition of 1.0 at. pct Zn to the Mg-2.5Gd-0.1Zr alloy reduces the 0.2 pct proof strength and increases the minimum creep rate, resulting from the formation of γ′ basal plates at the expense of β′ precipitates. The replacement of 1.0 at. pct Gd by Y in the Mg-2.5Gd-1.0Zn-0.1Zr alloy leads to a substantial reduction in the minimum creep rate, even though it does not cause much change to the 0.2 pct proof strength. The reduced minimum creep rate is attributed to a much lower diffusivity of Y atoms than Gd in the solid magnesium matrix. An increase in the Gd content from Mg-1.5Gd-1.0Y-1.0Zn-0.1Zr to Mg-2.5Gd-1.0Y-1.0Zn-0.1Zr leads to a denser distribution of precipitates, a higher 0.2 pct proof strength, and a further reduction in the minimum creep rate.

Determination of the Optimum Conditions for Leaching of Zinc Cathode Melting Furnace Slag in Ammonium Chloride Media

This research is part of a continuing effort to leach zinc from zinc cathode melting furnace slags (ZCMFSs) to produce zinc oxide. The slag with an assay of 68.05 pct Zn was used in ammonium chloride leaching for zinc extraction. In this paper, the effects of influential factors on extraction efficiency of Zn from a ZCMFS were investigated. The Taguchi’s method based on orthogonal array (OA) design has been used to arrange the experimental runs in order to maximize zinc extraction from a slag. The softwares named Excel and Design-Expert 7 have been used to design experiments and subsequent analysis. OA L25 (55) consisting of five parameters, each with five levels, was employed to evaluate the effects of reaction time (t = 10, 30, 50, 70, 90 minutes), reaction temperature [T = 313, 323, 333, 343, 353 (40, 50, 60, 70, 80) K (°C)], pulp density (S/L = 20, 40, 60, 80, 100 g/L), stirring speed (R = 300, 400, 500, 600, 700 rpm), and ammonium chloride concentration (C = 10, 15, 20, 25, 30 pctwt), on zinc extraction percent. Statistical analysis, ANOVA, was also employed to determine the relationship between experimental conditions and yield levels. The results showed that the significant parameters affecting leaching of slag were ammonium chloride concentration and pulp density, and increasing pulp density reduced leaching efficiency of zinc. However, increasing ammonium chloride concentration promoted the extraction of zinc. The optimum conditions for this study were found to be t4: 70 minutes, T5: 353 K (80 °C), (S/L)2: 40 g/L, R3: 500 rpm, and C4: 25 pctwt. Under these conditions, the dissolution percentage of Zn in ammonium chloride media was 94.61 pct.

Dendritic Growth Morphologies in Al-Zn Alloys—Part I: X-ray Tomographic Microscopy

Upon solidification, most metallic alloys form dendritic structures that grow along directions corresponding to low index crystal axes, e.g., $$\langle100\rangle$$ directions in fcc aluminum. However, recent findings[1,2] have shown that an increase in the zinc content in Al-Zn alloys continuously changes the dendrite growth direction from $$\langle100\rangle$$ to $$\langle110\rangle$$ in {100} planes. At intermediate compositions, between 25 wt pct and 55 wt pct Zn, $$\langle320\rangle$$ dendrites and textured seaweeds were reported. The reason for this dendrite orientation transition is that this system exhibits a large solubility of zinc, a hexagonal metal, in the primary fcc aluminum phase, thus modifying its weak solid–liquid interfacial energy anisotropy. Owing to the complexity of the phenomenology, there is still no satisfactory theory that predicts all the observed microstructures. The current study is thus aimed at better understanding the formation of these structures. This is provided by the access to their 3D morphologies via synchrotron-based X-ray tomographic microscopy of quenched Bridgman solidified specimens in combination with the determination of the crystal orientation of the dendrites by electron-backscattered diffraction. Most interestingly, all alloys with intermediate compositions were shown to grow as seaweeds, constrained to grow mostly in a (001) symmetry plane, by an alternating growth direction mechanism. Thus, these structures are far from random and are considered less hierarchically ordered than common dendrites.